FUJI ELECTRIC REVIEW Vol.65-No.3,2019

Whole Number 266, ISSN 0429-8284 FUJI ELECTRIC REVIEW

2019 Vol.65 No. 3 Energy Solutions Contributing to Stable and Optimal Power Supply

Energy Solutions Contributing to Stable and Optimal Power Supply Vol.65 No.3 2019

Printed on recycled paper Fuji Electric Korea Co., Ltd. Overseas Subsidiaries Sales of power distribution and control equipment, drive control equipment, Non-consolidated subsidiaries rotators, high-voltage inverters, electronic control panels, medium- and * large-sized UPS, and measurement equipment Tel +82-2-780-5011 America URL http://www.fujielectric.co.kr/ Fuji Electric Corp. of America Fuji Electric Co.,Ltd. (Middle East Branch Offi ce) Sales of electrical machinery and equipment, semiconductor devices, drive Promotion of electrical products for the electrical utilities and the industrial control equipment, and devices plants Tel +1-732-560-9410 Tel +973-17 564 569 URL https://americas.fujielectric.com/ Fuji Electric Co., Ltd. (Myanmar Branch Offi ce) Reliable Turbine Services LLC Providing research, feasibility studies, Liaison services Repair and maintenance of steam turbines, generators, and peripheral Tel +95-1-382714 equipment Tel +1-573-468-4045 Representative offi ce of Fujielectric Co., Ltd. (Cambodia) 2019 Providing research, feasibility studies, Liaison services Energy Solutions Contributing to Stable and Optimal Fuji SEMEC Inc. Tel +855-(0)23-964-070 Vol.65 No. Power Supply Manufacture and sales of door opening and closing systems 3 Europe Tel +1-450-641-4811 Fuji Electric is engaged in stabilizing and optimizing electric power Asia Fuji Electric Europe GmbH Sales of electrical/electronic machinery and components supply by supporting power infrastructure through reliable technologies Fuji Electric Asia Pacifi c Pte. Ltd. Tel +49-69-6690290 in order to contribute to the response to the changes in the energy sup- Sales of electrical distribution and control equipment, drive control equip- URL https://www.fujielectric-europe.com/ ment, and semiconductor devices Fuji Electric France S.A.S ply and demand environment and sophistication of social infrastructure Tel +65-6533-0014 URL http://www.sg.fujielectric.com/ Manufacture and sales of measurement and control devices and industrial systems. We are also pursuing innovation in energy and Tel +33-4-73-98-26-98 Fuji SMBE Pte. Ltd. URL https://www.fujielectric.fr/en environment technology, and working to create high value-added, envi- Manufacture, sales, and services relating to low-voltage power distribution Fuji N2telligence GmbH * board(switchgear, control equipment) ronmentally friendly products and systems used in Japan and overseas. Tel +65-6756-0988 Sales and engineering of fuel cells and peripheral equipment Tel +49 (0) 3841 758 4500 In this special issue, we will introduce our energy system solutions, URL http://smbe.fujielectric.com/ including one-stop solutions for power supply equipment and energy Fuji Electric (Thailand) Co., Ltd. China Sales and engineering of electric substation equipment, control panels, management systems (EMSs), as well as latest technologies that sup- and other electric equipment Fuji Electric (China) Co., Ltd. Tel +66-2-210-0615 Sales of locally manufactured or imported products in China, and export of port competitive components, such as transformers, switchboards, and URL http://www.th.fujielectric.com/en/ locally manufactured products Tel +86-21-5496-1177 uninterruptible power systems (UPSs) that contribute to power supply Fuji Electric Manufacturing (Thailand) Co., Ltd. URL http://www.fujielectric.com.cn/ stabilization and optimization. Manufacture and sales of inverters (LV/MV), power systems (UPS, PCS, switching power supply systems), electric substation equipment (GIS) and Shanghai Electric Fuji Electric Power Technology vending machines (Wuxi) Co., Ltd. Tel +66-2-5292178 Research and development for, design and manufacture of , and provision of consulting and services for electric drive products, equipment for Fuji Tusco Co., Ltd. industrial automation control systems, control facilities for wind power Manufacture and sales of Power Transformers, Distribution Transformers and generation and photovoltaic power generation, uninterruptible power Cast Resin Transformers systems, and power electronics products Tel +66-2324-0100 Tel +86-510-8815-9229 URL http://www.ftu.fujielectric.com/ Wuxi Fuji Electric FA Co., Ltd. Fuji Electric Vietnam Co.,Ltd. * Manufacture and sales of low/high-voltage inverters, temperature control- Sales of electrical distribution and control equipment and drive control lers, gas analyzers, and UPS equipment Tel +86-510-8815-2088 Tel +84-24-3935-1593 URL http://www.vn.fujielectric.com/en/ Fuji Electric (Changshu) Co., Ltd. Manufacture and sales of electromagnetic contactors and thermal relays Fuji Furukawa E&C (Vietnam) Co., Ltd. * Tel +86-512-5284-5642 Engineering and construction of mechanics and electrical works URL http://www.csfe.com.cn/ Tel +84-4-3755-5067 Fuji Electric (Zhuhai) Co., Ltd. Fuji CAC Joint Stock Company Manufacture and sales of industrial electric heating devices Provide the Solution for Electrical and Process Control System Tel +86-756-7267-861 Tel +84-28-3742-0959 URL http://www.fujielectric.com.cn/fez/ URL www.fujicac.com Fuji Electric (Shenzhen) Co., Ltd. PT. Fuji Electric Indonesia Manufacture and sales of photoconductors, semiconductor devices and Sales of inverters, servos, UPS, tools, and other component products currency handling equipment Tel +62 21 574-4571 Tel +86-755-2734-2910 URL http://www.id.fujielectric.com/ URL http://www.szfujielectric.com.cn/ P.T. Fuji Metec Semarang Fuji Electric Dalian Co., Ltd. Manufacture and sales of vending machines and their parts Manufacture of low-voltage circuit breakers Tel +62-24-3520435 Tel +86-411-8762-2000 URL http://www.fms.fujielectric.com/ Fuji Electric Motor (Dalian) Co., Ltd. Fuji Electric India Pvt. Ltd. Manufacture of industrial motors Cover Photo: Sales of drive control equipment and semiconductor devices Tel +86-411-8763-6555 Tel +91-22-4010 4870 (1) Transformer with vegetable oil (palm fatty acid ester), URL http://www.fujielectric.co.in Dailan Fuji Bingshan Vending Machine Co.,Ltd. (2) 145-kV downsized gas-insulated switchgear (GIS), FUJI ELECTRIC REVIEW vol.65 no.3 2019 Fuji Gemco Private Limited Development, manufacture, sales, servicing, overhauling, and installation (3)“UPS7400WX-T3U” modular UPS date of issue: September 30, 2019 of vending machines, and related consulting Design, manufacture, sales, and engineering for drive control systems Tel +86-411-8754-5798 Tel +91-129-2274831 Dalian Fuji Bingshan Smart Control Systems Co., Ltd. editor-in-chief and publisher KONDO Shiro Fuji Electric Philippines, Inc. Corporate R & D Headquarters Energy management systems, distribution systems, and related system Manufacture of semiconductor devices engineering Fuji Electric Co., Ltd. Tel +63-2-844-6183 Tel +86-411-8796-8340 Gate City Ohsaki, East Tower, Fuji Electric (Malaysia) Sdn. Bhd. Fuji Electric (Hangzhou) Software Co., Ltd. 11-2, Osaki 1-chome, Shinagawa-ku, Manufacture of magnetic disk and aluminum substrate for magnetic disk Development of vending machine-related control software and develop- (1) Tokyo 141-0032, Japan Tel +60-4-403-1111 URL http://www.fujielectric.com.my/ ment of management software http://www.fujielectric.co.jp Tel +86-571-8821-1661 Fuji Electric Sales Malaysia Sdn. Bhd. URL http://www.fujielectric.com.cn/fhs/ editorial offi ce Fuji Electric Journal Editorial Offi ce Sales of energy management systems, process automation systems, Fuji Electric FA (Asia) Co., Ltd. c/o Fuji Offi ce & Life Service Co., Ltd. factory automation systems, power supply and facility systems, and Sales of electrical distribution and control equipment vending machines Tel +852-2311-8282 1, Fujimachi, Hino-shi, Tokyo 191-8502, Tel +60 (0) 3 2780 9980 Japan URL https://www.my.fujielectric.com/ Fuji Electric Hong Kong Co., Ltd. Fuji Furukawa E&C (Malaysia) Sdn. Bhd. * Sales of semiconductor devices and photoconductors Fuji Electric Co., Ltd. reserves all rights concerning the republication and publication after translation Tel +852-2664-8699 (3) Engineering and construction of mechanics and electrical works into other languages of articles appearing herein. URL http://www.hk.fujielectric.com/en/ Tel +60-3-4297-5322 All brand names and product names in this journal might be trademarks or registered trademarks of Hoei Hong Kong Co., Ltd. their respective companies. Fuji Electric Taiwan Co., Ltd. (2) Sales of electrical/electronic components The original Japanese version of this journal is“FUJI ELECTRIC JOURNAL” vol.92 no.3. Sales of semiconductor devices, electrical distribution and control equip- Tel +852-2369-8186 ment, and drive control equipment URL http://www.hoei.com.hk/ Tel +886-2-2511-1820 Contents Energy Solutions Contributing to Stable and Optimal Power Supply

[Preface] In Pursuit of Stable and Optimal Power Supply in the Future 122 NAKANISHI, Yosuke

Energy Solutions Contributing to Stable and Optimal Power Supply 124 MORIMOTO, Masahiro MATSUMOTO, Yasushi

Latest Design and Analysis Technologies for 132 Miniaturizing Substation Equipment HIKOSAKA, Tomoyuki HAYASHIDA, Hirokazu ENAMI, Yoshiaki

New Generation MOLTRA with Improved Energy Savings and 137 Earthquake Resistance MIYATA, Tomokazu

Compact Medium-Voltage Switchgear for Data Centers 142 IWAMOTO, Satoshi FUJIMOTO, Yoshio OTA, Hiroshi

UPSs for Hyper Scale Data Centers 147 SATO, Atsushi YAMAGATA, Yoshihiko HAMADA, Ippei

“UPS7000HX-T4” High-Efficiency UPS with Continuous Commercial 151 Power Feeding and Quantity Control Function YASUMOTO, Koji HAMADA, Ippei SORIMACHI, Naohiro

Testing Equipment Contributing to Quality Improvement and 156 Environmental Impact Reduction of High-Capacity Power Electronics Equipment UMEZAWA, Kazuyoshi YAMADA, Toshiya CHIDA, Yukihiro

“Comprehensive Equipment Management Service” 161 Supporting Optimization of Equipment Maintenance FUKUSHIMA, Soji

One-Stop Solution for Power Supplies of Large-Scale Facilities 166 MURAGISHI, Takuro TAKAHASHI, Jun

Technology of Digital Substation for Advanced 170 Maintenance and Operation ISHIGAMI, Yuta SUGITA, Kohei NOGAWA, Michio

Countermeasures Against the Introduction of Large Amounts of 176 Renewable Energy in the Distribution Field and Support for BCP MATSUEDA, Tsurugi MOCHIZUKI, Masaki JINTSUGAWA, Toru

Power Demand-Supply Management System and VPP Solution 183 OKABAYASHI, Hiroki TERADA, Takeo FUJIO, Takahiro

New Products

1,700-V Line-Ups of 7th-Generation “X Series” IGBT Modules 189 Storage Battery Systems That Reuse EV Batteries 192 7th-Genenation “X Series” 1,200-V/2,400-A RC-IGBT Modules 195

FUJI ELECTRIC REVIEW vol.65 no.3 2019 Preface In Pursuit of Stable and Optimal Power Supply in the Future

NAKANISHI, Yosuke *

In this preface, I would like to overview the his- Kyoto Protocol came into force in 2005. Meanwhile in torical context of power systems in Japan and consider Japan, the 2011 Great East Japan Earthquake caused the future power systems to achieve stable and optimal serious damage to power facilities and brought about the power supplies. nuclear accident in Fukushima. Since this accident, the Supplying power in Japan was done with simple and way of using power sources has greatly changed to en- small-scale systems in the early days. The power out- hance power system resilience to disasters and to attain puts were manually controlled according to changes in a decarbonized society. In addition, as the Electricity demand. As time passed and the power grids have grew System Reform was accelerated the operational method in size and complexity, they became increasingly difficult of power systems involving several operators has also to manually manage and operate the entire systems ef- enormously changed. For example, New businesses have ficiently. In the mid-1950s, telecommunication technol- emerged: operation of distributed power sources, such as ogy using analog telemeters was introduced and, during renewable energy sources, and various power storage fa- the 1960s, automatic power supply systems went into cilities such as pumped-storage power plants, as well as online operation using digital computers. By this time, services for supporting these facilities, such as electricity the national power supplies were managed by ten private supply and demand aggregation. These in turn have cre- power companies, and each of them developed hierar- ated needs for new solutions to achieve system operations chical, integrated lateral systems with the central load- that take account of the role sharing of power sources dispatching center and regional load-dispatching liaison within the power systems and their uncertainty. More offices. Furthermore, the advancement of computer and specifically, power electronics components for wind and information technology in the late 1970s made it pos- solar power generation, which is uncertain and fluctu- sible to introduce remote monitoring and control systems ating power source, and storage batteries for smoothing (telecontrol equipment) that allow single control centers such fluctuation are controlled at high speed. Opera- to monitor and control multiple substations and also to tional control is therefore required that can deal with the introduce distribution automation systems in 6.6 kV volt- collaborative role sharing of other power sources and un- age class. In this way, computer-based remote control certain dynamics. and following automatic control methods have been es- Furthermore, because of the participation of mul- tablished, and highly reliable power systems have been tiple operators, optimized planning and operation come operated, contributing to the country’s economic growth. to be necessary in terms of many uncertain items, such Those power systems have reliably supplied stable power as facilities plans including power sources and transmis- mainly through the development of large-scale power sion lines, operation plans, and market trading. In these supplies and construction of bulk power grids to enable handling of the uncertainties, it is necessary to provide power transmission to major consumption areas. The es- efficient, optimal operational control of the systems and tablishment of reliable power systems was led by systems to supply the facilities and functions of the systems, ac- and their components built according to appropriate sys- cording to the structural classification of uncertainties. tem specifications developed by system operators under One is about known issues, which can be statistically ex- the mutual cooperation of both system operators and plained. Another is about unknown issues, which can be component manufactures. Additionally, the establish- expressed only in sets or ranges. The other is about un- ment of such system functions has been encouraged by knowable issues, which derive from mutually exclusive constant research and development performed by those scenarios or unpredictable events. collaborative parties and relevant academies. Now I would like to consider the stable and optimal I will now describe the trend in power systems in power supplies in the future to solve these issues and recent years. Environmental issues had been discussed uncertainties. Power systems, of which operations ac- through global warming conference even before the cording to ideal operational plans are difficult to perform, are fundamentally prone to various uncertainties, * ‌Doctor of Engineering, Graduate School, Faculty of Science such as changes in demand and accidents. Therefore, and Engineering, Waseda University when computers were initially introduced to power sys-

122 FUJI ELECTRIC REVIEW vol.65 no.3 2019 tems, their system design presupposed the following system design is required at the whole system level and three states and their transition in system operation: a at the individual cluster level even in a new power sys- steady and stable operational state including preventive tem composed of multiple operators across a number of control, an emergency state due to accidents that neces- consumers. I hope that, in the new institutional design sitate response control, and a recovery state that results in the future, power facilities and their functions will from the emergency control and congested events leading be designed on the basis of these three states and tran- to efforts to recover to steady operational state. These sitions between them, which are agreed by all relevant three states were defined, and functions that correspond parties, to maintain system reliability and stably supply to them were built into the system. Such an integrated electricity. Energy Solutions Contributing to Stable and Optimal Power Supply Energy issue:

In Pursuit of Stable and Optimal Power Supply in the Future 123 Current Future Status and Outlook

Energy Solutions Contributing to Stable and Optimal Power Supply

MORIMOTO, Masahiro * MATSUMOTO, Yasushi⁑

1. Introduction nance services by combining competitive components such as transformers, switchboards and unin- Changes in the energy supply and demand en- terruptible power systems (UPS) with other systems vironment and sophistication of social infrastruc- such as energy management systems. ture and industrial systems has increased the need Figure 1 provides an overview of Fuji Electric’s for stable power supply, as well as stable operation power electronics systems energy business. We and energy savings in equipment in factories and have been strengthening our systems business facilities. Furthermore, visualization and optimi- by combining components, such as transformers, zation using the Internet of Things (IoT) is being switchboards and UPSs with control systems that required for after-sales services such as equipment use measuring equipment; control equipment; elec- maintenance due to human-resource shortages in tric distribution, switching and control devices; and equipment management. Southeast Asia has been power electronics equipment. In this paper, we will seeing considerable economic growth and this has describe the current status and future outlook of en- increased investment in social infrastructure and ergy solutions that contribute to stable and optimal factories. As a result, new challenges have emerged power supply. regarding how to supply energy stably and efficiently. Fuji Electric is providing its Comprehensive Electrical Equipment Solutions as packaged services covering from installation work to mainte-

Power electronics systems energy business Power electronics systems industry business Stable supply and optimization of energy Automation and energy savings Energy Management Power Supply and ED&C Automation Social solutions Facility Systems components IT Equipment solu- construction tions

Engineering services

IoT Control equipment EMS O&M

Power receiving and distribution equipment,

Power electronics switches and Measuring Information solutions equipment control equipment instruments

Power semiconductors Sensors

Fig.1 Overview of Fuji Electric's power electronics systems energy business

* Power Electronics Systems Energy Business Group, Executive Officer, Fuji Electric Co., Ltd.

⁑ Power‌ Electronics Systems Energy Business Group, Fuji Electric Co., Ltd.

124 2. Technology Supporting Competitive (a) First unit of palm-fatty-acid ester oil transformer Components

2.1 Substation technology The core equipment in power systems consists of substation equipment, such as transformers (b) First unit of of dry air C-GIS and switchgear. The demand for the introduction of these equipment is expected to grow strongly throughout the world due to the progress in developing new power systems in Southeast Asia, the (c) 275-kV transformer with Middle East and Africa. In Japan, growth in power slip-on cables demand has slowed due to initiatives to save energy by companies and individuals following the Great East Japan Earthquake. On the other hand, the demand for the replacement of equipment is expected to grow because nearly half of the transformers and switchgear in use are over 40 years and 30 years old respectively. Figure 2 shows products that utilize substation technology. Fuji Electric has been developing and installing environmentally friendly products for over 10 years, such as palm-fatty-acid ester oil (d) Transformer with transformers that utilize plant-derived palm-fatty- 275-kV polymer acid ester oils as insulating and cooling media in- bushings stead of scarce oil-derived mineral oils, as well as cubicle-type gas insulated switchgear (C-GIS) that Fig.2 Products that utilize substation technology

use dry air as an insulating medium instead of SF6 Solutions Contributing to Stable and Optimal Power Supply Energy gas, which can induce global warming in the event big data analysis using artificial intelligence (AI).

of leakage. Furthermore, we are actively employing Against this backdrop, investment by data center issue: new technologies, such as 275-kV polymer bushings (DC*1) operators, including mega-cloud vendors, has for transformers that have significantly improved been thriving. New constructed DCs tend to become seismic performance compared to conventional por- extremely large in scale worldwide. celain bushings, as well as slip-on connections for One of the very important equipment to sup- 275-kV cables used with transformers designed to port DC availability is a UPS. As DCs grow in size, reduce on-site assembly periods. the amount of electricity being consumed is becom- In Japan and abroad, there is increased demand ing massive. Therefore, UPSs need to be highly ef- for more reliable and compact equipment. To meet ficient. In order to improve the efficiency of UPS, these needs, we have been working to improve our Fuji Electric has utilized low-loss silicon carbide analysis technologies. (SiC) devices*2, an advanced neutral-point-clamped (A-NPC) 3-level conversion circuit*3 and a continu- 2.2 Facility power supply technology ous commercial power feeding system*4. Moreover, Digital data has been expanding massively due the latest UPS systems come with quantity control to the use of virtual currencies and smart payments functions for executing autonomous control so that in the financial industry, autonomous driving and multi-unit UPS systems can operate with the high- electrification in the automobile industry, IoT tech- est level of efficiency (Refer to “UPSs for Hyper nology connecting everything to the Internet, and Scale Data Centers” on page 147).

*1: Data center (DC) down voltage and thermal conductivity, and *4: ‌Continuous commercial power This is a generic term for buildings they can achieve high breakdown voltage, feeding system dedicated to holding and operating Internet low loss and high-temperature operation. This is a system, which during normal servers and other equipment related to data commercial power supply conditions, sup- communications and fixed, mobile and IP *3: 3-level conversion circuit plies power directly to equipment connected telephones. This is a type of multi-level converter to the commercial power supply. During a that significantly reduces the power loss of power failure, it supplies power to connected *2: SiC devices power converters, such as power supplies equipment by converting battery power from They have excellent characteristics as and inverters. DC to AC using an inverter. power devices, such as high dielectric break-

Energy Solutions Contributing to Stable and Optimal Power Supply 125 We released the “UPS7400 WX Series” modular UPS to facilitate capacity and availability improvement for equipment (see Fig. 3). Maximum single- unit capacity has been increased to 1,000 kVA compared with the conventional rating of 500 kVA. The system’s modular structure enables continuous operation even if some of the modules breakdown, thereby increasing availability. For the backup power of the UPS, we are utilizing lithium-ion batteries because they can be downsized to a greater extent than conventional lead-acid batteries. This series is introduced at DC that need (a) IEC compliant (b) 7.2-kV metal clad to reduce the footprint of electrical equipment in or- 24-kV switchgear switchgear der to secure space for server installation. In the DC sector, we plan to release prod- Fig.4 ‌IEC compliant switchboard and compact switchboard ucts that meet the requirements for increased server density and large scale facilities (Refer regard to the continuity of operation for equipment. to “UPS7000HX-T4” High-Efficiency UPS with Furthermore, in conventional technologies, the hot Continuous Commercial Power Feeding and gas generated by arc during internal short circuit Quantity Control Functions” on page 151). has been generally released externally using ducts. Although the Japanese market for switchboards However, recently, hot gas needs to be cooled to a is mature, it is still growing steadily at an annual safe temperature before discharging. To meet this rate of 1.5%(1). In this sector, transition to renew- requirement, we have started releasing IEC stan- able energies, such as wind and photovoltaic power dard certified products as shown inFig. 4(a). generation, has progressed to reduce CO2 emissions. Equipment for DCs is often installed in ur- As a result, there is high demand for low-voltage ban areas where it is difficult to secure space. panels. In addition, the market for DC, as one type Therefore, it is necessary to reduce the footprint of IoT infrastructure, is expected to continue to of installations. To meet this need, we have devel- grow, also creating demand for high-voltage panels. oped a compact medium-voltage switchgear that en- The switchboard market has maintained a high ables front-side maintenance as shown in Fig. 4(b). growth rate of 4.7% in Southeast Asia(1). Safety This has reduced the installation area by about has always been a major priority for personnel 70% compared with conventional products (Refer who maintain switchboards. Therefore, one of the to “Compact Medium-Voltage Switchgear for Data requirements of switchboards is that they utilize Centers” on page 142). metal-clad switchgear capable of external operation In the future, we plan to continue to reduce the that enables movement toward the operating posi- size of our medium-voltage switchgear for Japanese tion of the vacuum circuit-breaker (VCB) from out- and international markets, while also advancing side the door with the front door closed. our metalworking without using plating and weld- Recently, equipment operation and operator ing so that we can provide environmentally friendly safety requirements have further increased. For switchboards based on the 3R principle (i.e. reduce, example, there is demand that the live part of the reuse and recycle). disconnecting part be protected with a metal shut- ter. Classifications are also being specified with 2.3 Equipment maintenance technology The recent development of IoT has made it possible to collect previously uncollectible types of data. This has helped commence the era of smart maintenance that utilizes the new analysis method with analytics AI for analyzing collected data(2). Fuji Electric provides field services for the products it has delivered to customers in the form of maintenance contracts. Equipment owners are requiring support services that cover not only equipment maintenance and troubleshooting, but also comprehensive management of the equipment. Equipment management operations start with the formulation of maintenance strategies and plans, and cover a wide range of areas, includ- Fig.3 “UPS7400WX Series” ing maintenance implementation, maintenance data

126 FUJI ELECTRIC REVIEW vol.65 no.3 2019 Table 1 Distribution equipment mega trends and needs Operation Analysis Maintenance Market Distribution equipment 1 2 3 Megatrend management* management* management* background need ◦ Economic develop- Operation plan Analytics AI Maintenance plan ment in Southeast Asia ◦ Timely equipment AI Globalization ◦ Trade friction investment acceleration ◦ Spread of ◦ Flexible facility scal- e-commerce ability ◦ M&A based business expansion Maintenance Operation Data inspection and ◦ Bundled equipment monitoring analysis abnormality ◦ Declining birthrate ordering and aging popula- recovery Shortage ◦ Automated inspec- in the tion tion Japanese ◦ Reduction in work- labor force ing hours ◦ Efficiency Maintenance free Operation Maintenance ◦ Lack of engineers ◦ information information ◦ Long-life products ◦ Flexible facility scal- Innovation in ◦ Smart factories ability production Use of robots *1: Cloud remote monitoring system ◦ ◦ Visualization *2: AI engine and BI (business intelligence) tools technology ◦ Flexible production *3: Equipment management support system ◦ Automation ◦ Failure prediction Learning functions ◦ Automated diagnosis Spread of IoT ◦ Fig.5 Functional configuration of O&M service platform ◦ AI ◦ Life expectancy di- Faster com- agnosis munication ◦ Utilization of big speeds data ◦ Failure analysis management, equipment management, and main- ◦ Spread of smart ◦ Optimization control devices tenance personnel education and training. We ◦ High efficiency Environmental ◦ Environmentally are providing equipment management services performance ◦ Reduction of envi- resistant products for these tasks called “Comprehensive Equipment ronmental burdens ◦ Redundancy Management Service.” Improvement ◦ Abnormal weather ◦ Cogeneration in security Comprehensive Equipment Management ◦ BCP ◦ Emergency power and safety generation facilities ◦ Resilience Service is built on an Operation & Maintenance performance ◦ Instantaneous drop (O&M) service platform as shown in Fig. 5. The countermeasures

O&M service platform has functions to support the Solutions Contributing to Stable and Optimal Power Supply Energy operation management, maintenance management In addition to this, however, the acceleration of the

and analysis management tasks defined in ISO worldwide economy has shortened the up and down issue: 18435 (O&M integration model). It integrates and trends of business cycles in all industries, resulting analyzes operating information collected during op- in the need for flexible and timely facility expan- eration management and maintenance information sion in accordance with the state of the economy. collected during maintenance management. By re- Furthermore, one-stop solutions are becoming more flecting the results in operation and maintenance popular as services ranging from maintenance and plans, the service contributes to stable operation inspection to labor-savings of construction manage- of equipment and reduction of equipment mainte- ment, including budget control, design arrange- nance costs (Refer to “Comprehensive Equipment ments, construction arrangements, and delivery Management Service Supporting Optimization of time management. Along with this trend, compre- Equipment Maintenance” on page 161). hensive ordering of facilities is increasing to stream- Furthermore, introducing a remote monitoring line business processes from equipment investment system can detect and recover from abnormalities to operation. faster. In addition to high quality and reliability, the increasing size of DCs requires scalability of add- 3. Energy System Solutions ing equipment according to demand without installing all equipment at the initial construction stage. 3.1 One-stop solution for power supply equipment Semiconductor plants require equipment to be scal- Fuji Electric is providing its customers with able and maintainable without stopping operations, optimal solutions by capturing the mega-trends while placing a heavy emphasis on quality and surrounding the power supply equipment shown in safety. On the other hand, assembly plants need Table 1. Conventionally, redundancy has played an to achieve both economics and business continuity important role in securing a stable supply of power. plans (BCP*5).

*5: Business continuity plan (BCP) continuing operations during emergencies that a company suffers an emergency such BCP is a plan that is utilized as a to enable continuation or speedy recovery as a natural disaster, large fire or terrorist means for performing the business opera- of core business operations, while minimiz- attack. tions required during normal operation and ing damage to business assets in the event

Energy Solutions Contributing to Stable and Optimal Power Supply 127 Moreover, customers are tending to order equip- systems. CO2 emissions cannot be increased due ment as a bundled set ranging from power receiving to environmental concerns, and this has made it facilities to low-voltage facilities instead of order- difficult to construct new thermal power plants. ing them individually as they did in the past, and Therefore, there are increased expectations for this is partly because they are facing a shortage of other types of adjusting capability, such as elec- supervisory engineers. Therefore, Fuji Electric has tricity storage systems, and various demonstra- been offering its one-stop solution for power supply tion projects are already underway. The use of equipment (Refer to “One-Stop Solution for Power utility customer equipment (generators, storage Supplies of Large-Scale Facilities” on page 166). batteries, EVs, etc.) is also being studied. (b) Expansion of new business operator entry 3.2 Energy Management Systems The start of full deregulation of retail electric- The Basic Energy Plan for 2030 has been pre- ity began in April 2016. As of February 2019, the sented under Japan’s basic energy policy 3E + S*6. share of power producers and suppliers (PPSs*7) Furthermore, the “Electricity System Reform” has increased to 14.6% of the total electricity sales. been underway since 2015. The reform is expected However, not all business operators are perform- to solve various issues through the use of technologi- ing well, and some are starting to withdraw. cal innovations such as AI and IoT. (1) Power exchange market (1) Changes in power industry The power exchange market has initiated Figure 6 shows the overall roadmap of the en- reforms to improve efficiency and reduce elec- ergy mix and Electricity System Reform presented tricity charges through competition. The vol- by the Japanese government. Specific changes ow- ume of transactions at wholesale power ex- ing to these 2 initiatives are as follows: changes has grown significantly from approxi- (a) Changes in power system operation due to mately 2% in 2016 to approximately 30% as expanded adoption of renewable energies of this year. Capacity mechanisms and sup- In order to maximally use and stably supply and balancing markets are being devel- ply renewable energies, it is essential to build a oped by the Organization for Cross-regional next-generation power network that can handle Coordination of Transmission Operators. system constraints and secure power quality and (2) Separation of power generation and trans- adjusting capability. New system usage rules are mission being studied in regard to system constraints. In In order to increase the neutrality of the terms of power quality, equipment is being en- power transmission and distribution sector and hanced to solve voltage problems in distribution enable various business operators to fairly use

2015 2016 2017 2018 2019 2020 2030 Energy mix Renewable Renewable energy energy 15% 22% to 24% Power system reform Wide-area organizations Full deregulation of retail electricity Separation of power production and supply Power exchange market ★Start of negawatt market transactions ★Start of gross bidding ★Start of indirect auctions ★Start of base load market transactions ★Start of supply and demand adjustment market transactions ★Start of capacity market transactions Power distribution field Smart meter installation Increase of power providers and suppliers Consolidation of power providers and suppliers Public appeal for regulation power Emergence and expansion of VPP* Power exchange, negawatt exchange vitalization and ancillary service providers

*VPP: Virtual power plant

Fig.6 Roadmap for energy mix and power system reform

*6: 3E + S *7: ‌Power producers and suppliers to local power companies (general electric This is a basic point of view established (PPS) companies) in order to supply their custom- under Japan’s energy strategy. It consists Power producers and suppliers (PPS) ers with power. of energy stabilization security, economic do not actually own the power line facilities efficiency, environmental compliance and required to provide electricity to household safety. consumers. Therefore, they pay usage fees

128 FUJI ELECTRIC REVIEW vol.65 no.3 2019 transmission and distribution networks, legal cated. unbundling and complete elimination of pric- In order to meet the needs of power stabiliza- ing regulations will begin in 2020. The power tion on the basis of this expectation, Fuji Electric transmission and distribution sector is strong has been developing products and services for the demanded to improve management efficiency energy management system shown in Fig. 7. In and are working to reduce operating costs while particular, we have been developing electricity stor- introducing and maintaining power systems age systems, supply and demand management sys- that can secure stable power supply despite the tems, VPP systems, and distribution automation increasing use of unstable renewable energy systems equipped with advanced voltage control sources. functions. Furthermore, we have developed and of- (2) Initiatives by Fuji Electric fered a product that digitalizes substations, as well On the basis of the present situation, the follow- as a power system analysis simulator for a system ing changes are expected to take place in the power that includes distributed power sources and storage distribution field (power system operation, equip- batteries to verify system reliability and operational ment configuration, etc.): safety. (a) Introduction of power stabilization systems (3) Overview of products and services supporting The introduction of electricity storage sys- EMS tems and use of utility customer facilities are (a) Electricity storage systems for power stabili- expanding to maintain power quality (frequency, zation and VPP voltage). We have developed a control system that uti- (b) Emergence and expansion of new services lizes storage batteries to stabilize the frequency Business operators are emerging that offer of power systems, balance the supply and de- new services such as virtual power plants (VPP*8) mand of electricity, and solve challenges such and ancillary services*9, targeting newly created as those related to utility customer load level- markets. ing and BCP. Fuji Electric has been participat- (c) Sophistication of existing systems ing in the “Virtual Power Plant Construction In order to achieve both stable power supply and Demonstration Project Using Consumer

and cost reduction, a voltage control function will Energy Resources” sponsored by the Ministry of Solutions Contributing to Stable and Optimal Power Supply Energy be required that can handle existing systems and Economy, Trade and Industry, and has developed

on-site equipment that will have been sophisti- an electricity storage server that comprehen- issue:

Cloud service : New products : Existing products to be enhanced Power producer Supply and demand management VPP Utility customer Solar Electricity retailer Plant

New service providers Wind Collaborative IoT Ancillary service 1 aggregation VPP* Electricity storage system 2 DR* Large-quantity Thermal Electricity storage system utility customer

Power generation management system Transmission and distribution providers IoT Electricity storage system Supply and demand Distribution automation system SVC management Small-quantity utility customer Protection relay Hydro Power system Storage battery Electricity analysis simulator storage system

*1 VPP: Virtual power plant *2 DR: Data response

Fig.7 Energy management system products and services

*8: Virtual power plant (VPP) ages. operation, and regulation of voltage and fre- A VPP consolidates and controls mul- quency. When power producers and suppli- tiple small-scale power plants and demand *9: Ancillary service ers are treated as separate companies, the suppression systems as a single power plant. This refers to an operational service for provision of ancillary services is regarded as It is expected to contribute to load leveling, maintaining the quality of supplied power. a business. absorption of over-supply of renewable en- Functionality may include supply and de- ergy, and power supply during power short- mand balance monitoring, power system

Energy Solutions Contributing to Stable and Optimal Power Supply 129 sively manages storage batteries of utility cus- lem, a voltage control system is needed for dis- tomers dotted around, an interface for the elec- tribution systems that include the increasing tricity storage server and utility customer storage number of renewable energy sources. Therefore, batteries, and electricity storage IoT to effectively Fuji Electric has conducted joint research with use storage batteries. We are currently verifying Tohoku Electric Power Co., Inc. to develop a new the effectiveness of these developments (Refer separately-exited static var compensator (SVC) to “Power Demand-Supply Management System for distribution systems. In addition, we have and VPP Solution” on page 183). developed functions to support the planning of (b) Power supply and demand management sys- power systems and the settings of a voltage con- tem trol system to optimally control distribution sys- The start of full deregulation of retail elec- tems. In the future, we are planning to add these tricity began in April 2016. To coincide with functions to a distribution automation system this, we released a cloud service to support that monitors and controls distribution systems. the operation of power producers and suppliers. We have also developed and delivered a wide- The cloud service uses AI and other technologies area backup system that utilizes a distributed to forecast power demand, while providing vari- server arrangement to support BCP and ensure ous functions such as electricity purchase, plan- continued supply of stable power in the event of ning, and supply and demand monitoring. We a disaster. Figure 9 shows the configuration for are providing it by on-premises*10 services and the wide-area backup type distribution automa- by adding functions for power producers. Figure tion system (Refer to “Countermeasures Against 8 shows an example of our power supply and the Introduction of Large Amounts of Renewable demand management system and VPP solution Energy in the Distribution Field and Support for (Refer to “Power Demand-Supply Management BCP” on page 176). System and VPP Solution” on page 183). (d) Substation digitalization (c) Separately-exited SVCs for distribution sys- We are researching how to digitalize sub- tems and distribution automation systems stations to improve the efficiency of substation The spread of renewable energies has equipment replacement, reduce costs and fa- brought about the problem of voltage increase cilitate access to substation information. For in distribution systems. To deal with this prob- example, instead of having a large number of

Before plan review Power retail Utility customer energy management service Power utility base : Demand increase location A. demand suppression B. Utility customer Power retail Utility customer energy request and activation (resource) suppressible management service Demand amount calculation plan (1) Procurement Power demand-supply Large-capacity storage battery shortage management system RA system calculation (3) Demand (Planned-value ○BG imbalance suppression kWh suppression (4) Suppression request balancing) adjustability (Power cost reduction) Procurement study request amount, plan (2) Calculation of target period verification A. Demand sup- (3) Demand suppression B. Resource side Time demand pression request study request Suppressible suppression amount and activation (11) Demand suppression amount and target period (5) Resource status D. Demand sup- activation calculation verification pression result C. Demand sup- ○Charging and verification pression Plan revision discharging plan (7) Demand suppressible control (7) Demand ○Present state amount report (8) Suppressible suppressible ○Future state (15) Demand suppression Demand plan amount verification amount results report report (6) Suppressible amount,

kWh period calculation Procurement (9) Demand plan plan review (13) Storage (11) Demand Utility customer group Time C. Demand suppression battery control (10) Demand suppression control of power utility suppression activation (12) Allocation of activation Utility Utility customer (resource) suppression customer Imbalance verification amount to each resource D. Demand suppression (15) Demand VPP storage battery system result verification Demand results suppression (13) Storage battery control (16) Demand results ○Battery status and output suppression report ○Interconnection point instantaneous value kWh result verification (14) Result verification Procurement ○Demand suppression plan control response (17) Imbalance Time verification (b) Demand suppression utilizing power demand-supply management system and large-capacity storage battery RA system (a) Process flow during demand suppression

Fig.8 Power supply and demand management system and VPP solution

*10: On-premises information systems are installed and oper- On-premises is a type of operating ated within the facility managed by a user method where servers, software and other (usually a company).

130 FUJI ELECTRIC REVIEW vol.65 no.3 2019 Distribution Distribution Distribution Distribution automation console automation automation automation console server A Tens to hundreds server B of km

Server A Sales Office Server B Sales Office

Tens of km Power IP network

Distribution Distribution Distribution automation automation automation console console console

Client Sales Office 1 Client Sales Office 2 Client Sales Office n

Fig.9 Wide-area backup distribution automation system

control cables that connect field equipment, such Substation equipment communicates via the digi- as switches, with protective control devices, we tal network compliant with an international stan- use process bus to research substation monitor- dard, and this simulator can also simulate the ing and control systems by digitalizing substa- control systems of power systems. This technol- tion information (Refer to “Technology of Digital ogy is utilized in the research on substation digi- Substation for Advanced Maintenance and talization described above. Operation” on page 170). （e）Power system simulator 4. Postscript We have developed an analog simulator that

simulates power system phenomena under vari- In this paper, we introduced some of the major Solutions Contributing to Stable and Optimal Power Supply Energy ous system configurations, loads and power gen- energy solutions that Fuji Electric is working on and

eration states. by utilizing reduced current. The described the current status and future outlook of issue: simulator consists of a power equipment model our endeavors. and cable system and uses reduced current to Fuji Electric intends to contribute to society simulate a power system that includes distrib- through the promotion of the stable supply and opti- uted power sources, such as renewable energy, mization of electricity. and storage batteries. This simulator can reproduce phenomena that digital simulators have not References been able to analyze. It also makes it possible (1) Asia-Pacific Switchgear Market, Forecast to 2025. to verify the enhancement of equipment and the Frost & Sullivan, 2019. change of operational according to the intro- (2) Yamada, T. et al. Overview of Fuji Electric IoT duction of large quantities of renewable energy Platform. FUJI ELECTRIC REVIEW. 2018, vol.64, sources, as well as to analyze system accidents. no.3, p.136-139.

Energy Solutions Contributing to Stable and Optimal Power Supply 131 Latest Design and Analysis Technologies for Miniaturizing Substation Equipment HIKOSAKA, Tomoyuki * HAYASHIDA, Hirokazu * ENAMI, Yoshiaki⁑

ABSTRACT

To meet the need of miniaturization for substation equipment, including transformers and switchgear, Fuji Elec- tric has developed design and analysis technologies capable of miniaturizing conventional substation equipment by 30% or more. We have developed a 50-MVA transformer for overseas markets that achieves a 30% reduction in volume. This downsizing was achieved by collating the measurement results from verification models created with three-dimensional electric field analysis, magnetic field analysis, and thermal fluid analysis technologies that we have established. We have also developed a new 145-kV GIS that achieves installation space savings of 30% and mass reduction of 35% by utilizing coupled analysis technologies for electric circuits, electromagnetic fields and thermal fluids, as well as coupled analysis technologies for electric fields and thermal fluids.

1. Introduction change in phenomenon due to a change in specifications, and consistency between analysis and actual Substation equipment, such as transformers and results. During the design stage, however, both deliv- switchgear is major equipment in substations, which ery time and quality were important and there was a are the core of electricity infrastructure development. time constraint on large-scale analysis. Therefore, we Since any failure in such equipment may greatly af- previously used a simplified calculation program based fect society, a high level of quality and reliability are on the analysis technologies used in the development required. On the other hand, it is especially difficult stage or two-dimensional analysis to save calculation to acquire sites for substations in urban areas, and the time. sites tend to be small. As a result, there is a growing Owing to three-dimensional CAD and develop- need for substation equipment with compactness. ments in computer hardware and software in recent Fuji Electric has been providing the global market years, designers can come to perform highly accurate with both transformers and switchgear that have been three-dimensional analysis. Consequently, Fuji Electric proven in the industry for more than half a century. has also actively applied three-dimensional analyses in We have developed design and analysis technologies design to achieve downsizing and improved reliability that can downsize substation equipment by 30% or of power transformers. Among these, this paper de- more compared with conventional models, while main- scribes the latest three-dimensional analysis technolo- taining the equipment reliability established over the gies of electric field analysis, magnetic field analysis years. This paper describes these latest design and and thermal fluid analysis, together with the result of analysis technologies. applying their technological results to products.

2. Latest Design and Analysis Technologies for 2.1 Electric field analysis technology Transformers The lead connecting the winding and bushing of a transformer is positioned three-dimensionally. This Transformers are designed and manufactured one means that three-dimensional electric field analysis by one in accordance with the required specifications of is effective in determining the insulating distance be- the respective customers. tween the lead and tank. In order to achieve high-voltage performance, com- Consequently, we created the lead insulation veri- pactness and low power dissipation, Fuji Electric has fication model shown in Fig. 1. By setting the insu- invested a lot of time in large-scale analysis during lating distance, diameter of the lead conductor and the development stage. It has done this by focusing thickness of the insulating paper as parameters, we on the phenomenon and principles to be identified, the measured the breakdown voltage under AC voltage application condition and lightning impulse voltage appli- * Power Electronics Systems Energy Business Group, Fuji cation condition. From the measured values, we con- Electric Co., Ltd. firmed that we could obtain a breakdown field with the

⁑ Corporate R&D Headquarters, Fuji Electric Co., Ltd. three-dimensional electric field analysis shown in Fig. 2. We then verified the validity of the design standard

132 Electrode Sample Yoke (Mock tank)

Coil Voltage application

Crepe paper insulated electrode (Mock lead)

Insulating distance Stacking direction

Fig.1 Lead insulation verification model Fig.3 ‌Measurement model of the magnetic flux perpendicular to the plate surface

Earth electrode (flat plate) Mineral oil Magnetic flux Electric density field Coil High High

Yoke

Low Low Sample

Model coil Solutions Contributing to Stable and Optimal Power Supply Energy (a) Analysis model (b) Analysis result (cross-section) issue: Fig.4 Example of three-dimensional magnetic field analysis Fig.2 ‌Example of electric field analysis result for the lead insulation verification model ample of the three-dimensional magnetic field analysis result for the measurement model of the magnetic for the insulating distance between the lead and tank, flux perpendicular to the plate surface shown in Fig. 3. which had conventionally been determined by compar- Figure 5 shows a comparison of the analysis results of ing a two-dimensional electric field analysis result with the conventional method, analysis results of the new an actual measurement result. As a result, we found method adopting equivalent electric conductivity*2 and that we could reduce the insulating distance between actual measurement values. Adopting equivalent elec- the lead and tank by about 15% compared with con- tric conductivity improved the calculation accuracy ventional products. especially in the area with high magnetic flux density.

2.2 Magnetic field analysis technology 2.3 Thermal fluid analysis technology It is important to have a proper understanding of Previously, three-dimensional analysis of thermal the magnetic properties of structural materials, such fluid had a problem of taking a long time due to the as common steel or high-tensile steel used for tanks large-scale calculation. In recent years, however, the and frames of transformers, to evaluate stray load development of calculation technology has made it pos- loss*1 caused by the magnetic flux inside the trans- sible to calculate even the model of a total system that former. requires large-scale calculation as shown in Fig. 6. In order to learn the stray load loss caused by eddy To improve the cooling efficiency inside the wind- current on SS400 rolled steel for general structure, we ing, we fabricated the following three full-size wind- created a sample by cutting it into a ring with an outer ings with different internal structures and measured diameter of φ60 mm and inner diameter of φ48 mm and measured the loss when magnetic flux flowed in- *1: Stray load loss: Loss caused by an eddy current gener- side the plate surface of the structural material. Next, ated by the interlinkage between the magnetic flux that we created the 30 mm-square measurement model leaked from the winding and the structural material. shown in Fig. 3 and measured the loss when magnetic *2: Equivalent electric conductivity: Electric conductivity flux flowed in the perpendicular direction (stacking obtained with consideration to the skin effect introduced direction) to the plate surface. Figure 4 shows an ex- for accurate evaluation of stray load loss.

Latest Design and Analysis Technologies for Miniaturizing Substation Equipment 133 Actual measurement Temperature distribution Velocity distribution Temper- ature Magnetic field analysis result (Conventional method) or flow Magnetic field analysis result (New method) speed High 15

(W/kg) 5 Low Loss per unit weight 0 0 0.2 0.4 0.6 Case 1 Case 2 Case 3 Case 1 Case 2 Case 3 Magnetic flux density (T) (a) Magnetic flux along plate surface Fig.7 ‌Analysis result of the winding temperature distribution 15 and insulation oil velocity distribution

10 Measured value Analysis value

Loss (W) 5 Case 1 Case 2 Case 3

0 0 0.1 0.2 0.3 0.4 Magnetic flux density (T) (b) Magnetic flux perpendicular to plate surface

Fig.5 Comparison‌ of the conventional method with the new method considering equivalent electric conductivity Position inside winding inside Position winding inside Position winding inside Position

Temperature (°C) Temperature (°C) Temperature (°C)

Fig.8 ‌Comparison of the measured values with analysis results of winding temperature distribution

structure to miniaturize transformers.

2.4 Application of the achievements The three-dimensional electric field, magnetic field and thermal fluid analysis technologies established in this way were applied to the development of 50-MVA class transformers for the market outside Japan shown in Fig. 9. These transformers were reduced by 30% in volume compared with conventional products. Fig.6 Thermal‌ fluid analysis model of a total system (winding, iron core and cooling unit) the temperature rise inside them. ◦ Case 1: Duct flow winding ◦ Case 2: Zigzag flow winding (improved type) ◦ Case 3: Zigzag flow winding (conventional type) Figure 7 shows the temperature distribution inside the windings and the velocity distribution of insulating oil calculated with three-dimensional thermal fluid analysis. As shown in Fig. 8, we found that the temperatures actually measured at five positions inside the winding almost agreed with the analysis values in Fig. 7. By utilizing this three-dimensional thermal fluid analysis, we proceeded with optimizing the winding Fig.9 Downsized transformer

134 FUJI ELECTRIC REVIEW vol.65 no.3 2019 3. Latest Design and Analysis Technologies for 12.0 ms Temper- ature Switchgear High

3.1 Coupled analysis technology In order to reduce the size and weight of gas insulated switchgear (GIS), Fuji Electric has been evalu- 19.4 ms ating the current breaking performance of gas circuit breakers (GCBs) according to the coupled analysis pro- Low cedure shown in Fig. 10. The electric circuit analysis section passes the result of calculating the arc current between the GCB contacts to the electromagnetic field and thermal fluid Fig.12 Example of the temperature distribution analysis of an analysis section. On the other hand, it receives the re- arc-extinguishing chamber sult of calculating the arc voltage from the electromagnetic field and thermal fluid analysis section in which the arc-extinguishing chamber to the space between our original electromagnetic field analysis program the three-phase conductors and to the tank side. The has been built into the user code of the fluid analysis temporal change in the density distribution of the hot software. The electromagnetic field and thermal fluid gas obtained through thermal fluid analysis is passed analysis section calculates the temperature and elec- to the electric field analysis. In electric field analy- tric conductivity of the arc. sis, the influence of the hot gas on the electric field strength is determined and used in evaluating the in- 3.2 Current breaking analysis technology sulation recovery performance. Figure 11 shows the analysis procedure to obtain Current breaking analysis reduces analysis time the insulation performance after current breaking. by using a two-dimensional axisymmetric analysis The hot gas that expanded due to the high tempera- model considering the movement of movable contact, ture generated during current breaking flows out from gas generation from the nozzle due to abrasion, and radiation heat transfer because the arc-extinguishing Solutions Contributing to Stable and Optimal Power Supply Energy chamber has an axisymmetric shape. To improving issue: both calculation speed and accuracy, the mesh size and Electric circuit analysis section calculation time are automatically adjusted so that the

Electric circuit time increment is set shorter in the period immediately before breaking and the mesh size is set finer in Voltage Current the part where an arc exists to capture the change in Electric potential arc shape.

Conductivity Figure 12 shows the result of analyzing the tem- Current density (Temperature) perature distribution when 12.0 ms and 19.4 ms has Thermal fluid Electromagnetic field passed after an arc generated at current breaking in Magnetic flux density 145-kV GIS and the current is reduced to zero under Electromagnetic field and thermal fluid analysis section conditions where the current is 36 kA, frequency is 50 Hz, and SLF (a line fault occurred at a short distance) is 90%. Fig.10 Coupled analysis flow 3.3 Insulation recovery analysis technology In general, the breakdown field Es of SF6 gas Electric field analysis Thermal fluid analysis (three-dimensional, steady) (three-dimensional, non-steady) is proportional to the power of gas density. Conse- quently, the breakdown field is calculated by using the Transitional recovery voltage Temperature T, pressure P gas density obtained with thermal fluid analysis. First, electric field analysis is performed with the Density ρ shape shown in Fig. 13(a) to obtain the electric field strength E at different points across the model. Next, Electric field strength E Reference electric field Es= a ρ b the flow amount and temperature of the hot gas flowing from the arc-extinguishing chamber of each phase Index E/Es are calculated with thermal fluid analysis and- ap The risk of electrical breakdown is expected at plied to the hot gas outflow surface in Fig. 13(b). The the place and time at which E/Es > 1. temporal change in the gas density distribution on the conductor surface whose insulation performance Fig.11 Insulation recovery analysis procedure will be evaluated is obtained, and then the breakdown

Latest Design and Analysis Technologies for Miniaturizing Substation Equipment 135 Supporting insulator

R phase S phase T phase Hot gas outflow U phase surface V phase W phase

(a) Electric field (b) Thermal fluid analysis model analysis model

Fig.13 Insulation performance analysis model Fig.15 External appearance of 145-kV downsized GIS field strength Es is compared with the strength of the electrical field E generated by the temporal change of gas density at the current breaking. As Fig. 11 shows, 3.4 Application of the outcome E/Es, which is the ratio of these values, is used at ev- By utilizing the coupled analysis technologies de- ery time and position as an actual evaluation index. scribed above and making quality improvements, Fuji Figure 14 shows the result of calculating the tem- Electric has developed the miniaturized GIS shown in poral change of E/Es by applying this method. E/Es Fig. 15, with the installation space reduced by 30% and exceeded 100% in the structure where a ground fault mass reduced by 35%. occurred, whereas 80% or less in the improved structure. We thus confirmed that the improved structure 4. Postscript can prevent the occurrence of an earth fault. This paper described the latest design and analysis technologies for downsizing substation equipment. 120 Structure where Active demand is expected for electricity infra-

(%) an earth fault S 100 structure development globally now and in the future. E occurred / It is also expected that the need for downsizing substa- E 80 tion equipment will increase continuously. 60 As a leading manufacturer of substation equipment, Fuji Electric will continue its efforts to achieve 40 further downsizing and make quality improvements Improved structure 20 of transformers and switchgear while paying attention to environmental issues. We will strive to steadily Electric field strength strength field Electric 0 0 20 40 60 80 improve design and analysis technologies in order to Time (ms) provide substation equipment that can satisfy our customers’ needs. Fig.14 ‌Example of insulation performance improvement achieved by shape improvement

136 FUJI ELECTRIC REVIEW vol.65 no.3 2019

* Fig.1 ‌ in shown as saving energy toenhance intended standards ficiency ef establishing been have countries many Moreover, 2014). Transformer Runner (Top transformers Runner Top for criteria judgment second the than performance transformers distribution MOLTRA* including high-voltage for in creasing is Demand Con (COP21). Change Framework Climate Nations on vention United the of Parties of the Conference 21st the in adopted Agreement” “Paris the on based policies energy implement and ronment 1. * 1‌

Electric Co.,Ltd. oe Eetois ytm Eeg Bsns Gop Fuji Group, Business Energy Systems Electronics Power : MOLTRA: Fuji Electric’s cast resin transformer (regis transformer resin cast Electric’s Fuji MOLTRA: : tered trademarkofFujiElectric Co.Ltd.) New GenerationMOLTRA withImproved Energy ntaie ae en tkn o rtc te envi the protect to taken being are Initiatives Introduction

Efficiency (%) being integratedintothepaneltofurtherenhanceearthquakeresistance. it designed optimally have con we itself, body energy transformer the standard improving to to addition in relative Furthermore, efficiency. sumption 130% of performance energy-saving an achieves that line-up a II,” MOLTRA Eco “Super- and MOLTRA” “Amorphous its of development the in technologies energy-saving its those utilized has Electric Fuji Moreover, MOLTRA. Earthquake. Japan including East Great the since resistance earthquake applications higher have to required been also distribution have transformers high-voltage in used transformers in performance 100.0 transformers onacountrybasis Comparison ofthemaximumefficienciescastresin 97.5 98.0 98.5 99.0 99.5 In recent years, initiatives to protect the environment have created greater demand for enhanced energy-saving enhanced for demand greater created have environment the protect to initiatives years, recent In 10 2013 Japan JISC4306: i. 1 Fig. Grade1Amorphousalloy China GB20052 Lk te uba (B standards, (GB) Guobiao the Like . Savings andEarthquakeResistance 1 ht ae ihr energy-saving higher have that 100 Grade 1Electromagneticsteel China GB20052 Capacity (kVA) - 2013 Europe IEC60076 2017 PEILevel2 Europe IEC60076 2017 PEILevel1 1,000 - 2013 - 20: - MIYATA, Tomokazu 20: 10,000 T C A R T S B A - - - - - Fig.2 “Super-EcoMOLTRAII” Transformer 2014 specified by Japanese Industrial Japanese Standards (JIS). by specified 2014 Runner Top Transformer for those than stricter are them of some ing ontheinstallationenvironment. depend available optionally are 2.0 and 1.5 to conform those and 1.0, of the criteria intensity seismic to design-basis conforms series These 2014. Transformer Top Run ner of that than efficiency higher consumption energy 130% achieved have Both same space. the installation almost “TopRunner maintaining the while than 2014” MOLTRA factors load all for efficiency (see II” MOLTRA “Super-Eco the and used, is alloy amorphous which in 2015, in MOLTRA” “Amorphous the released Electric Fuji 2014, Transformer Runner Top than performance continuity plan(BCP). on business placed a of viewpoint the from resistance earthquake been has importance 2011, in Earthquake n h ohr ad atr h Get at Japan East Great the after hand, other the On o rvd pout wt hge energy-saving higher with products provide To *

Fig. 2 Fig. ) in 2017 that provides higher provides that 2017 in ) - 137 - -

issue: Energy Solutions Contributing to Stable and Optimal Power Supply This paper describes new-generation MOLTRAs loss depends on both no-load loss and load loss. Con- (“Amorphous MOLTRA” and “Super-Eco MOLTRA II”) sequently, improving the efficiency in this region re- with improved energy-saving performance and earth- quires reducing both no-load loss and load loss. quake resistance. 3.2 “Amorphous MOLTRA” 2. Product Line-Up The use of amorphous alloy for the core material suppresses hysteresis loss and eddy-current loss, Figure 3 shows the MOLTRA product line-up. which compose no-load loss, lowering no-load loss to MOLTRAs conforming to Top Runner Transformer one-third of that of the Top Runner MOLTRA 2014. As 2014 are the Top Runner MOLTRA 2014, Amorphous a result, this product shows high efficiency in the low MOLTRA and Super-Eco MOLTRA II. The models load factor region as shown in Fig. 4. It delivers high with higher energy-saving standard achievement rate energy-saving performance in buildings or hospitals, have higher energy-saving performance. where the daily average load factor is low due to low electricity consumption at night. 3. Improving Energy-Saving Performance 3.3 “Super-Eco MOLTRA II” 3.1 Loss characteristics of transformers Thin, magnetic-domain-control steel sheets with JIS specifies energy consumption efficiency as total high magnetic flux density are used for the core. The loss in the specified reference load factor. Total loss design-basis magnetic flux density is optimized to re- can be expressed as the sum of no-load loss, which is duce no-load loss and downsize the core. Moreover, produced regardless of the load factor, and the product we selected copper for the conductor of the winding of load loss, which varies depending on the load factor, instead of conventional aluminum. This has reduced and the square of the load factor [Equation (1)]. the load loss compared with that of the Top Runner MOLTRA 2014. The installation space remains almost Energy consumption efficiency (W) = the same because the winding has been downsized. 2 m ...... No-load loss (W) + 100 × Load loss (W) (1) As Fig. 4 shows, the Super-Eco MOLTRA II shows higher efficiency than the Top Runner MOLTRA 2014 m: Reference load factor (%) in the entire load factor region. It is especially high Transformers with 500 kVA or lower capacity: in the high load factor region. It delivers high energy- 40% saving performance in data centers or water treatment Transformers with capacity exceeding 500 kVA: facilities, where the daily average load factor is high. 50% Figure 5 shows the radar chart comparison of the As can be seen from Equation 1, the no-load loss typical characteristics of the three-phase, 300-kVA accounts for a large part of the total loss in the low type of these products. The dimensions, mass and load factor region. Consequently, the efficiency in this other characteristics of Top the Runner MOLTRA 2014 region needs to be improved by the reduction of no- is set to 100, and the smaller the value the better. load loss. As for the high load factor region, the total Amorphous MOLTRA has improved energy consumption efficiency by reducing no-load loss significantly. Super-Eco MOLTRA II has improved energy consump- 140 tion efficiency by reducing both no-load loss and load 130 120 110 Amorphous Super-Eco Top Runner MOLTRA 2014 Reference energy MOLTRA MOLTRA II consumption efficiency Amorphous MOLTRA 100 Super-Eco MOLTRA II 99.6 90 High efficiency in the low load (%) 99.4 factor region High efficiency 80 First in the high load Top Runner factor region 70 Top Runner 99.2 MOLTRA MOLTRA 2014 60 Models of 99.0 20 years ago Top Runner 50 Transformer 2014 98.8

Energy-saving standard achievement rate 40 98.6 Year Efficiency (%) Amorphous Super-Eco MOLTRA II 98.4 MOLTRA Models of 20 years ago (FM-KF type) [JIS C 4306:1999] First Top Runner MOLTRA (FM-KT type) [JIS C 4306:2005] 98.2 The line-up includes both models to provide products best suited to users. Top Runner MOLTRA 2014 (FM-T14 type) [JIS C 4306:2013] Amorphous MOLTRA (FM-AT14 type) [JIS C 4306:2013] 98.0 10 20 30 40 50 60 70 80 90 100 Super-Eco MOLTRA II (FM-ST14 type) [JIS C 4306:2013] Load factor (%)

Fig.3 Product line-up Fig.4 Efficiency curves of three-phase, 300-kVA types

138 FUJI ELECTRIC REVIEW vol.65 no.3 2019 Energy consumption efficiency Top Runner MOLTRA 2014 Amorphous MOLTRA Super-Eco MOLTRA II Recommended 100 renewal Load loss Width Unit electric power charge: 16 yen/kWh period

100 100

Super-Eco MOLTRA II 100 100 Initial cost can be recovered in 14 years. No-load loss Depth (compared with Top Runner) 100 100 Paid cost Paid Amorphous MOLTRA Total mass Height Initial cost can be recovered in 9.5 years. Top Runner MOLTRA 2014 (compared with Top Amorphous MOLTRA Runner) Super-Eco MOLTRA II 0 5 10 15 20 25 Operating period (year) (a) Paid cost when load factor is 20% Fig.5 Typical characteristics of three-phase, 300-kVA types Recommended renewal Unit electric power charge: 16 yen/kWh period loss while maintaining almost the same installation space.

4. Replacing Existing Units

From the survey conducted by the Japan Electrical cost Paid Super-Eco MOLTRA II Initial cost can be Manufacturers’ Association (JEMA), the number of recovered in 11.5 years. high-voltage distribution transformers used for more (compared with Top Runner) than 20 years, which is the recommended renewal pe- Energy Solutions Contributing to Stable and Optimal Power Supply Energy riod, can be estimated to be about 1.2 million units in 0 5 10 15 20 25 Japan. Replacing aged transformers with the latest Operating period (year) issue: MOLTRAs conforming to Top Runner Transformer (b) Paid cost when load factor is 60% 2014 will not only improve energy-saving performance but also ensure higher reliability during operation in- Fig.6 Benefits of replacing existing units cluding earthquake resistance. The use of the Amor- phous MOLTRA or the Super-Eco MOLTRA II with portant to select a transformer in accordance with the high energy-saving performance, in particular, reduces actual load. loss generation, reduces the annual electric power charge, and allows the initial introduction cost to be re- 5. Enhancing Earthquake Resistance covered in about 10 years (see Fig. 6). It is also effective for addressing environmental problems to fight global 5.1 Aseismic design guideline warming because suppressed loss generation helps re- Fuji Electric had studied the transformer damage duce CO2 emissions. Figure 6(a) shows paid cost during caused by the Great East Japan Earthquake in 2011 the operating period when the load factor is 20%. As- and identified contributing factors in transformers, suming that the unit electric power charge is 16 yen/ switchboards and construction management. Since kWh and comparing with the case of the Top Runner then, we have clarified the earthquake resistance spec- MOLTRA 2014, the Amorphous MOLTRA and Super- ifications of transformers and been demanding atten- Eco MOLTRA II can recover the initial introduction tion to panel design and construction. The major points costs in 9.5 years and 14 years, respectively. After that during installation are as follows: point, the electric power charge can be saved. (a) Ensuring an extra length of the wiring to be con- Figure 6(b) shows paid cost when the load factor nected is 60%. Compared with the Top Runner MOLTRA (b) Ensuring the flexibility of the wiring 2014, Super-Eco MOLTRA II will bring benefits in 11.5 (c) Controlling the clearance for seismic snubbers years. On the other hand, the efficiency of the Amor- (d) Ensuring the insulation for low-voltage conduc- phous MOLTRA is lower than that of the Top Runner tors MOLTRA 2014 when the load factor is 60% as shown (e) Not using anti-vibration rubber mounts (when a in Fig. 4, so that the replacement will not bring cost vibration-isolating base is used) benefits. The efficiency can thus decrease depending Attention should be paid when a transformer with on the load factor, resulting in the energy-saving ef- anti-vibration rubber mounts is installed on a vibra- fect not being as high as expected. Therefore, it is im- tion-isolating base because the rigidity becomes lower

New Generation MOLTRA with Improved Energy Savings and Earthquake Resistance 139 Table 1 ‌Design-basis seismic intensity criteria for building equip- Displacement of a Displacement of a ment obtained by the local seismic intensity method Terminal transformer transformer Seismic class Floor S A B Higher floors, roof and penthouse 2.0 1.5 1.0 Terminal Middle floors 1.5 1.0 0.6 Basement floors and first floor 1.0 0.6 0.4

(From Guideline for Aseismic Design and Construction of Building Equipment)

Table 2 Displacement of a transformer Displacement of transformer* Design-basis (mm) Aseismic seismic intensity category Without anti- With anti- criteria vibration vibration Front view Side view rubber mounts rubber mounts (a) Displacement of a transformer 0.4, 0.6, 1.0 Normal 50 or less 50 or less

Fixing seat Wire, angle, etc. Outside the 1.5, 2.0 Enhanced 50 or less scope of JEM-TR252

* ‌Displacement (1,000 kVA or lower)

displacement of a transformer specified in JEM-TR252 even with anti-vibration rubber mounts being attached (see Table 2). The specifications of the types exceeding 1,000 kVA and the displacement when a vibration- Front view Top view isolating base is provided or when anti-vibration rub- (b) Relative displacement suppression methods ber mounts are attached for enhancing earthquake resistance are determined by the agreement with the Fig.7 Displacement‌ of a transformer and the methods of sup- customers. pressing the relative displacement 5.3 Suppressing the relative displacement to the panel than in the case of installing a transformer alone, re- enclosure sulting in degraded earthquake resistance. In addition When a vibration-isolating base is used or anti- to the above, JEM-TR252 (the Guide for Movement of vibration rubber mounts are attached to the trans- Distribution Transformers(1)) was established, which former to enhance earthquake resistance, the sway of defines the displacement required of transformers the upper part of the transformer can increase. The for each aseismic category, displacement evaluation methods for suppressing the relative displacement to method and displacement suppression method [Ex- the panel housing include attaching fixing seats on the ample: Fig. 7(b)] as a guideline for the displacement of upper part of the transformer and securing the trans- transformers during an earthquake [see Fig. 7(a)] and former to the panel enclosure with wire or angles, as the relative displacement to the panel enclosure. The shown in Fig. 7, or holding snubber rubbers attached to displacement of the terminal section is defined as the the transformer by the panel enclosure. displacement of the transformer because the displace- These measures can suppress relative displacement of the terminal section is expected to be largest ment by synchronizing the movement of the trans- for typical transformers. former and panel enclosure so that they sway in the same direction. There is, however, the risk of an ac- 5.2 Displacement of a transformer cident being caused by the insufficient strength of the The client of the construction or the designer of panel housing. It is necessary to ensure optimal aseis- the construction, structure or facility determine the mic design by considering the transformer and panel design-basis seismic intensity criteria for transform- as a single unit. ers by considering the seismic safety of the building, Figure 8 shows models of the installation to a the floor number of the electric room, and the seismic panel. Instead of the anti-vibration rubber mounts class, which is categorized according to the importance included with the MOLTRA as standard, a vibration- of the equipment (see Table 1). The MOLTRAs conform isolating base with seismic snubbers [see Fig. 8(b)] to Top Runner Transformer 2014 meet the require- is mounted to further reduce vibration from being ments for the design-basis seismic intensity criteria of transmitted to the building. During an earthquake, 1.0 through the modification of the plate thickness and these seismic snubbers that suppress the sway of the the shape of structural members. The specifications of transformer main body and fixing seats are attached to 1,000-kVA or lower types satisfy the 50 mm or lower the upper part of the transformer to secure the trans-

140 FUJI ELECTRIC REVIEW vol.65 no.3 2019 former to the panel enclosure, thus enhancing earthquake resistance [see Fig. 8(c)]. It is also possible to replace the fixing seats with snubber rubbers shown in Fig. 8(d). Providing appropriate clearance between the Fig. 8 (c) snubber rubbers and panel enclosure can prevent the transmission of vibration during operation and suppress sways during an earthquake.

6. Postscript

This paper described the new-generation MOLTRAs with improved energy-saving performance and earthquake resistance based on initiatives to protect the en- Fig. 8 (b) vironment and problematic cases after the Great East (a) Inside the panel Japan Earthquake. Fuji Electric will continue our efforts to develop the MOLTRA line-up best suited for the use environment by finding out the needs of our customers.

References Seismic snubber (1) JEM-TR252: 2014. Guide for Movement of Distribution Transformers. The Japan Electrical Manufacturers’ Association. (Japanese).

(b) Vibration-isolating base Energy Solutions Contributing to Stable and Optimal Power Supply Energy issue:

Fig.8 Models of installation to the panel

New Generation MOLTRA with Improved Energy Savings and Earthquake Resistance 141 Compact Medium-Voltage Switchgear for Data Centers IWAMOTO, Satoshi * FUJIMOTO, Yoshio * OTA, Hiroshi *

ABSTRACT

Data centers that have been flourishing since around 2005 are often built near urban areas, and there is therefore a need to be compact and space saving of electrical equipment installed. From above background, we have released a compact medium-voltage Switchgear for data centers that is 900 mm wide and 900 mm deep while maintaining the front maintenance type and does not require maintenance space on the back side. For downsizing, the function of the vacuum circuit-breaker (VCB) fixed frame (Cradle) was integrated into the Switchgear side. In addition, a current transformer (CT) with optimal specifications was adopted and performed down size of the CT. As a result, the installation area of total equipment including UPS has been reduced to about 70% compared to the previous model.

1. Introduction VCB ON VCB OFF DS ON DS OFF Data centers that have been increasing rapidly since around 2005 are often built in urban areas because they can recover quickly in case of failure and high-speed communication is possible thanks to the location close to Internet exchange points. However, it has been difficult to acquire a site that can offer a large enough installation area. In order to address this issue, the electrical equipment installed in data centers needs to be compact and space saving. Economy: Good Economy: Excellent As for switchboards, equipment in the data center, Maintenance: Excellent Maintenance: Good a front maintenance type that allows compact installa- Recovery from accident: Excellent Recovery from accident: Good tion has become the mainstream. (a) System A (b) System B From the above background, Fuji Electric has developed and released compact, front maintenance type Fig.1 Comparison‌ of power receiving and distribution systems medium-voltage switchgear products intended for use used in data centers in data centers. cidents are easy. 2. System Configuration and Product Overview The configuration example shown in Fig. 2 consists of three circuits, a medium-voltage system circuit, an There are many types of medium-voltage power re- uninterruptible power supply switching system circuit ceiving and distribution systems used in data centers. and a low-voltage system circuit. System A is used Figure 1 shows two examples — one is a system con- for the medium-voltage system circuit and generally sisting of vacuum circuit-breakers (VCBs) only (called consists of medium-voltage power receiving panels, System A in this paper) and the other is a system in medium-voltage feeder panels and input transformer which disconnect switches (DSs) are used only for the panels. power supply switching positions and VCBs are used The external appearance of the medium-voltage for other positions (System B). In System A, VCBs feeder panel product developed for data centers is that allow easy switching operation and can be drawn shown in Fig. 3, the front view of its inside is shown in out from the switchboard are used instead of DSs. Fig. 4 and its major specifications are shown inTable 1. These VCBs can be drawn out from the switchboard for The medium-voltage feeder panel shown in Fig. 3 inspection, so that maintenance and recovery from ac- and Fig. 4 has two VCBs in a stacked position. The devices required for the control circuit are grouped together and positioned on the door. * Power Electronics Systems Energy Business Group, Fuji Electric Co., Ltd.

142 Table 1 ‌Rated specifications of the medium-voltage feeder panel Medium-voltage system circuit Item Specifications Medium-voltage input High-voltage input Applicable standard JEM 1425-CW Power receiving panel Power receiving panel Installation environment Indoor Medium-voltage Medium-voltage Medium-voltage Medium-voltage Rated voltage 3.6/7.2 kV feeder panel 2 feeder panel 1 feeder panel 2 feeder panel 1 Rated frequency 50/60 Hz Rated bus current 600 A Rated short-time current 20 kA/second Commercial 22 kV Rated dielectric frequency strength Lightning 60 kV impulse Input Input Input Input transformer transformer transformer transformer Degree of protection IP2X* panel panel panel panel Dimensions W × D × H (mm) 900 × 900 × 2,300

Uninterruptible Vacuum circuit-breaker (VCB) Motor charging spring type power supply switching Ratio of trans- 100-150-300/1 A UPS UPS UPS UPS system circuit Current transformation (3 taps) input input input input former (CT) Rated load 5 VA

I/O panel 3 I/O panel 2 I/O panel 1 I/O panel * IP2X: This code means that the product is rated as “dustproof degree 2” and “no degree for waterproof.” It is also called “finger protection,” meaning the degree of protection that prevents a human finger from getting in. UPS UPS UPS UPS unit unit unit unit BAT* BAT BAT BAT

3 2 1 Bus panel Solutions Contributing to Stable and Optimal Power Supply Energy

Bus Vacuum circuit-breaker tie (VCB) issue: panel Maintenance bypass panel

Current transformer (CT)

UPS output UPS output Low-voltage system circuit

* BAT: Battery External cable connection space Fig.2 Example of a system for data centers

Fig.4 ‌Front view of the inside of the medium-voltage feeder panel Digital protection relay

Test terminal (CTT type) 3. Downsizing

We downsized the medium-voltage switchgear to reduce the installation area of the total equipment.

Test terminal (VTT type) We took the following measures in order to adopt the front maintenance structure and limit the depth dimension to the same as that of the uninterruptible power system (UPS) which will be installed side-by- side: (a) Downsizing of the internal structural member (VCB storage section) by integrating the function of the VCB fixing frame (cradle) to the Fig.3 ‌External appearance of the medium-voltage feeder panel switchgear side (b) Downsizing by developing and using a current

Compact Medium-Voltage Switchgear for Data Centers 143 transformer (CT) with optimal specifications for conventional products. data centers 3.2 Downsizing the medium-voltage switchgear 3.1 Reducing the installation area of the total equipment (1) Downsizing of the VCB storage section The developed medium-voltage switchgear has a In general, a drawer type VCB is a combination of structure allowing for maintenance work on the front the VCB unit and a cradle. side. Conventional products required a working space As shown in Fig. 6, we integrate the function of also on the back side of the switchgear so that an extra the cradle for drawing out and disconnecting the VCB installation area was required in an electrical room. to the switchgear side, reducing the dimensions from Unlike conventional products, the new medium-voltage 1,100 mm wide × 1,500 mm depth to 900 mm wide × switchgear does not require a working space on the 900 mm depth. back side so that it can be installed against a wall. (2) Downsizing of current transformers (CTs) Moreover, the input transformer panel which will be Conventional products were designed to use CTs installed next to the UPS was also downsized to be 900 that support large-scale equipment capacities with no mm in both width and depth. We designed it to have restriction on the field. In order to support various the same depth dimension as that of the UPS so that ratios of transformation, the dimensions were deter- they can be installed side-by-side. Since work from mined to secure enough room for a CT with a primary the back side is unnecessary, it is also possible to in- current of 2,000 A. This made the downsizing impos- stall the switchgear and UPS back-to-back. This has sible. lightened the restrictions on the layout to allow switch- We checked the delivery record and found out boards to be positioned in one place. The external that many of the power receiving and distribution sys- cables connected to the switchboards can be grouped tems used in data centers use transformers rated for together. It should be noted that the layout for data 550 kVA, 1,000 kVA and 2,000 kVA. Consequently, we centers also requires consideration to be given to set the primary current in three levels suitable for the spaces for replacing switchboards without stopping the capacity of the UPS, 100 A, 150 A and 300 A. In addi- power supply. After such consideration, we compared tion, the load on CTs has been decreasing due to the the installation area with that of the conventional lay- significantly improved performance of equipment con- out. As shown in the equipment installation example nected to the secondary side of CTs. This allowed us to of an electrical room in Fig. 5, the installation area downsize the CT by setting specifications of the rated of the total equipment including UPSs is reduced to load to 5 VA and the secondary current to 1 A. Fur- about 70% when compared with that of Fuji Electric’s thermore, as shown in Fig. 7, a tap changing mecha-

Conventional design : Space reserved for replacement New design : Space reserved for replacement

Working space Medium-voltage switchgear Medium-voltage switchgear-B Medium-voltage switchgear-A

Medium-voltage switchgear Medium-voltage switchgear-B*1 Medium-voltage switchgear-A*1 Working space

2 2 2 2 Working space No. 4 UPS peripheral panel* No. 3 UPS peripheral panel* No. 2 UPS peripheral panel* No. 1 UPS peripheral panel* mm No. 1 UPS peripheral panel No. 2 UPS peripheral panel*2 No. 1 UPS peripheral panel*2 No. 4 UPS peripheral panel No. 3 UPS peripheral panel No. 2 UPS peripheral panel No. 1 UPS peripheral panel

No. 2 UPS peripheral panel No. 4 UPS peripheral panel*2 No. 3 UPS peripheral panel*2 Working space mm Working space Battery No. 4 Battery No. 3 Battery No. 2 Battery No. 1

No. 3 UPS peripheral panel Battery No. 2 Battery No. 1 Battery No. 4 Battery No. 3 Battery No. 2 Battery No. 1

No. 4 UPS peripheral panel Battery No. 4 Battery No. 3 Working space Required building space: 13,00 0 Working space Low-voltage switchgear-A Low-voltage switchgear-A

Battery No. 2 Battery No. 1 Low-voltage switchgear-B Low-voltage switchgear-B

Battery No. 4 Battery No. 3 Required building space: 19,00 0 Working space

Working space Required building space: 20,000 mm

Low-voltage switchgear-A Low-voltage switchgear-A

*1: Medium-voltage switchgear refers to the following: Low-voltage switchgear-B Low-voltage switchgear-B Power receiving Medium-voltage Medium-voltage Medium-voltage panel feeder panel feeder panel feeder panel Working space

*2: UPS peripheral panel refers to the following: Required building space: 20,000 mm Input transformer Uninterruptible panel (VCB+TR) power system I/O panel

Fig.5 Equipment installation example of an electrical room

144 FUJI ELECTRIC REVIEW vol.65 no.3 2019 : VCB unit : Cradle part : Panel member

Cradle is used.

Front Back side side Cover Cover (Conventional (New design) design)

Frame

(a) Conventional frame structure (b) New frame structure Conventional design

Fig.8 Comparison of the frame structures

The cradle function is integrated into the switchgear side. nect external cables inside the panel. The space for cable connection and a space for VCB storage are divided by a pillar positioned at the center in the panel width direction. We changed the position Back side Front side of the pillar to allow workers to put their arms inside and connect external cables more easily.

3.3 Earthquake resistance Since the Great East Japan Earthquake in 2011, electrical equipment has been required to have higher Solutions Contributing to Stable and Optimal Power Supply Energy earthquake resistance. issue: New design On the other hand, downsizing, especially a reduction in the depth dimension, may weaken the rigidity Fig.6 ‌Comparison of the structures of the vacuum circuit- against a horizontal seismic force. breaker storage section (side view) To solve this problem, we build a housing structure as shown in Fig. 8 to ensure both strength and internal space. In conventional structures, a plate-like cover K L was secured onto the frame with a bolt inserted in the horizontal direction, so that the stress concentrated on the bolt. The new structure uses a box-shaped cover to k1 k2 k3 l enhance rigidity. Moreover, the cover is designed to be secured by surface contact with the frame to prevent stress from concentrating. Primary Secondary current connection We conducted a three sine wave vibration test by

300 A k1-l using a prototype in accordance with the Manual of Earthquake-Proof Construction for Switchgear and 150 A k2-l Controlgear Assemblies (JEM-TR144: 2017). We also 100 A k3-l conducted vibration tests by simulating the seismic waves of the past earthquakes: “El Centro Earthquake Fig.7 Current transformer (0.3 G maximum, three axes simultaneously),” “South- ern Hyogo Earthquake (0.6 G maximum, three axes nism has been used to support more than one primary simultaneously)” and “Great East Japan Earthquake current rating. (1.5 G maximum, three axes simultaneously).” As a We also prepare optional specifications of the CT result, we confirmed that the product is earthquake for a secondary current of 5 A and a rated load of 10 resistant satisfying the design-basis seismic intensity VA that makes it possible to select the primary current criteria of 2.0 and can provide enough resistance to in accordance with customer specifications to flexibly earthquakes that occurred in the past. meet customer requirements. (3) Facilitating external cable connection Downsizing switchgear makes it difficult to -con

Compact Medium-Voltage Switchgear for Data Centers 145 switchgear for data centers. 4. Postscript Fuji Electric will continue its efforts to satisfy customer demands and develop products with even higher This paper described compact medium-voltage reliability and safety.

146 FUJI ELECTRIC REVIEW vol.65 no.3 2019

(1). Equation with shown be can DC a of (PUE) fectiveness ef usage power The operators. DC on burden heavy a 2. infrastructure ofhyperscaleDCs. electricity high-capacity the support that centers data hyperscale for UPSs describes paper This energy. save to also efficiency high are and capacity facilities large have such to in required used UPSs electricity. of amount huge a consume they and years recent in ing increas been has DCs size) (ultra-large hyperscale of number The supply. power the with problem a of case in even continuously power stable supplies that (UPS) system power uninterruptible an is DCs of availability data. such collecting for availability high with (DCs) centers data and (IoT) Things of Internet the through the Internet to connected sensors various and numerous from data exchanging of capable infrastructure munication a Tech), (Cross system thatmergesvirtualandrealspacestogether. X-Tech social of use to the solutions through problems and development economic both achieve to intended society people-centered a 5.0,” ciety “So proposed has Japan of Government Office, Cabinet 1. *

Electric Co.,Ltd. oe Eetois ytm Eeg Bsns Gop Fuji Group, Business Energy Systems Electronics Power civn te ol f oit 50 eurs com requires 5.0 Society of goal the Achieving the of Plan Basic Technology and Science The The costs of electric power for running a DC place DC a running for power electric of costs The the supporting equipment of piece important One Current StatusoftheDCMarket Introduction compact, lightweightbatterypanelequippedwithlithium-ionbatteries,allowingDCstoimproveoperationalefficiency. the maximumsystemefficiencyandacontinuouscommercialpowerfeedingtoreducelossduringstablecom mercial powersupply.WehavealsodevelopedamoduleUPS,oneunitofwhichconsistsseveralpanels,and Fuji ElectrichasaddednewfunctionstoUPSsforDCs,includingcontrolofthenumberoperatingunitspursue

are indispensableinstabilizingtheoperationofDCsandrequiredtohavealargecapacityhighefficiency. Data centers(DCs)forstoringbigdataareincreasinginsizeyearbyyear.Uninterruptiblepowersystems(UPSs) SATO, Atsushi UPSs for Hyper ScaleDataCenters

YAMAGATA, Yoshihiko T C A R T S B A - - - - consider system configurations that maintain avail maintain ability whilereducingtheinstallationspace. that configurations operators system DC consider availability. ensuring for redundancy system installation higher with smaller relationship trade-off a A has space installed. be can IT equipment of number the more the equipment, IT than other equip the ment itself. of reliability the enhancing to addition in maintenance improving and system redundant a using by availability increase to operators DC for issue impor tant an is It years. five in once only hours four for suspended be may operations where system a to alent operating 99.99% as high as is IV Tier for A rate The level). (top IV Tier to I Tier from DCs (2). Equation with shown be can It operation. its continue can system the which for period the of percentage the indicates which availability, is operation DC in portant power consumedbyitemsotherthanITequipment. To improve this index, it is essential to reduce the reduce to essential is it index, this improve To PUE =‌ The smaller is the installation space for equipment for space installation the is smaller The of quality the categorizes LLC Institute, Uptime A= im be to considered factors the of one Moreover, MTTR MTBF A

MTBF MTBF

Power consumedbyITequipment Power consumed by entire DC / Power consumedbyentireDC : Meantimetorecovery : Meantimebetweenfailures : Availability HAMADA, Ippei + MTTR

��

(1) . This is equiv is This .

�� - 147 (2) (1) - - - - -

issue: Energy Solutions Contributing to Stable and Optimal Power Supply system, instead of operating all UPSs all the time. 3. UPS Efficiency Improvements 3.5 Continuous commercial power feeding 3.1 Non-insulated UPS Large-capacity UPSs used in large-scale DCs gen- Some transformers for voltage change or isolation erally use normal inverter feeding because it is highly are needed on the feeding route from a power receiving reliable. The reasons why this method is regarded point to loads. Increasing the number of transform- as highly reliable are that it can continuously supply ers increases loss. Consequently, a non-isolated UPS power at a constant voltage and frequency and that the with no internal transformers has been used widely feeding continues without instantaneous interruption in recent years. Using this non-isolated UPS makes it in case of a blackout because of the continuous opera- possible to optimize the number of transformers in the tion of the inverter. feeding route. In addition to IT equipment, UPSs in DCs are used for feeding power to air-conditioners and other equip- 3.2 Three-phase, four-wire, 400-V power feeding system(2) ment, and some load may allow voltage fluctuation or A three-phase, four-wire, 400-V UPS will output instantaneous interruption. Fuji Electric offers UPSs a voltage of approximately 230 V across the neutral with continuous commercial power feeding, which uses phase and another phase. Since this voltage is within a bypass feeding circuit to reduce power loss. the operating range for typical 200-V load equipment, Continuous commercial power feeding is a method there is no need for stepping down from 400 V to that puts the emphasis on feeding efficiency. When 200 V, reducing the loss incurred by transformers. the commercial power supply is normal, power is fed If, however, one-line ground fault (interphase directly to the load from the power supply. During a short-circuit) occurs on the load side, the ground-fault blackout, the power stored in the storage batteries is current is not isolated but reaches the output side of fed after the conversion into alternating current by the UPS. When this condition continues, the UPS may an inverter. Fuji Electric calls this function High Ef- stop. In order to prevent such a problem, the feeding ficiency Mode (HE mode) and has been incorporating circuit must be designed to have an appropriate load it into its latest models. Figure 1 shows a comparison branch breaker and design the feeding circuit so that a between normal inverter feeding and continuous com- ground fault at one point will not affect the feeding of mercial power feeding(3). other systems. In continuous commercial power feeding, the fluctuation in the AC power supply directly affects the load 3.3 Using low-loss devices during normal operation. When a blackout occurs, The UPS uses a three-level conversion circuit in the output voltage waveform is instantaneously inter- the pulse width modulation (PWM) converter for AC- rupted for about 1/4 of the cycle due to a delay in the DC conversion and the inverter for DC-AC conversion, detection time. Since this method feeds power to the and the circuit uses Fuji Electric’s proprietary reverse blocking-insulated gate bipolar transistors (RB-IGBTs) and power modules dedicated to three-level conver- Bypass AC sion. This has reduced switching loss that is produced switch AC when the device turns on or off, and lowered the ripple current to reduce loss also in the filter circuit. More- AC DC Inverter feeding over, Fuji Electric has selected a silicon carbide (SiC) device for the free wheeling diodes (FWDs) of the PWM Rectifier Inverter converter. Compared with conventional silicon (Si) Battery devices, SiC devices offer lower switching loss and con- Battery charging duction loss, allowing the UPS to reduce loss. (a) Normal inverter feeding

3.4 Quantity control Bypass AC AC switch In general, the efficiency of UPSs is low in the light AC load region and peaks in a specific heavy load region. Bypass feeding In a system where several UPSs are connected in par- DC allel, load current flows equally through each UPS. Consequently, when the load is small, the load per unit Rectifier Inverter Battery becomes even smaller, resulting in a significant degradation in the efficiency of the entire system. Battery charging To improve the efficiency of the entire system, this (b) Continuous commercial power feeding UPS changes the number of operating units to make the load on a single operating UPS close to the maxi- Fig.1 ‌Normal inverter feeding and continuous commercial mum efficiency by monitoring the load of the entire power feeding

148 FUJI ELECTRIC REVIEW vol.65 no.3 2019 load without using a converter, the power loss is lower UPSs are installed in an electrical room and LIBs use than that for normal inverter feeding. an electrolyte, which is as flammable as petroleum, manufacturers are required to provide a certain fire- 4. Optimization of UPS System Configuration prevention measure according to the Fire Service Act. Fuji Electric has solved such a challenge and has In addition to the high efficiency described in used LIBs manufactured by Samsung SDI Co., Ltd. Chapter 3, UPS systems in DCs are required to de- in the large-capacity UPS “UPS7000HX Series” and liver: easy equipment maintenance, enhanced main- “UPS6000DX Series.”(4) tainability for quick recovery from failure, scalability The advantages of using LIBs are as follows: for phased capital investment, compact size for saving (1) The expected lifespan is 15 years so that replace- installation space to reduce building costs, and low ment is unnecessary during the operating period running costs using long life parts. of the UPS (15 years) (the lifespan of lead-acid batteries is 7 to 9 years). 4.1 Modular UPS (2) Compared with lead-acid batteries, the footprint is A module UPS consists of several panels that have reduced to about half, and the mass is reduced to respective functions. For example, Fuji Electric’s mod- about 20%. ule UPS “UPS7400WX-T3U” is shown in Fig. 2. As (3) The backup time is longer than that for lead-acid shown in Fig. 2, this UPS includes three to four panels: batteries even at higher temperature. an I/O panel, a control panel and a UPS module panel, installed from the left. 4.3 Optimization of system configuration A modular UPS has the following features: In recent years, the capacity of UPSs has been in- (1) High reliability creasing as the server racks used for DCs are designed Redundant converters ensure continuous inverter to provide larger capacity. Moreover, the use of a par- feeding even if some of the modules fail. allel redundant system has become common for the (2) High maintainability UPS systems intended for DCs, so that the capacity Inspection and failure recovery are possible on a of the necessary peripheral equipment should also in- module basis while the inverter feeding is continued. crease. Although the capacity of an entire UPS system (3) High scalability including peripheral panels increases, there is a strong Solutions Contributing to Stable and Optimal Power Supply Energy The capacity can be increased by adding modules. demand for limiting any cost increase. issue: Fuji Electric has launched the “UPS7400WX Se- Fuji Electric’s efforts to meet such a demand are ries” modular UPS, having the features described described below: above. (1) Larger capacity of a single UPS unit Increasing the capacity of a single UPS unit will 4.2 Use of lithium-ion batteries (LIBs) cause the following effects: Conventional UPSs have used lead-acid storage (a) The number of panels, such as battery panels or batteries; however, these batteries have disadvantages peripheral panels, can be reduced, resulting in of being heavy and large. On the other hand, lithium- cost saving. ion batteries (LIBs) are compact and lightweight. In (b) The reduced number of pieces of equipment also recent years, although LIBs have been rapidly expand- helps lower the failure rate and improve avail- ing in applications, such as electric vehicles and power ability. storage units, their use in large-capacity UPS systems (2) UPS feeding system has not been increasing so much. This is because A parallel redundant system has been used in UPS systems to improve reliability. In this case, the output currents from the respective UPS units are aggregated to the output bus, and the bus and switches are required to endure large output currents. Since switches have a limitation to their capacity, UPSs are also limited in terms of their size. On the other hand, many DCs overseas that are rated as Tier IV class specified by Uptime Institute use 2N systems with static transfer switches (STSs). Fig- ure 3 shows configuration examples of a parallel redundant system and a 2N system. Like parallel redundant systems, 2N systems can also achieve high availability. Furthermore, when a UPS is assigned to each load equipment of a DC, the output bus capacity can be reduced. Consequently, it Fig.2 “UPS7400WX-T3U” modular UPS will be more important in the future to work in close

UPSs for Hyper Scale Data Centers 149 centers. Efficient operation of electric power and the technology for improving the availability of the entire system are essential factors in data center operations. We need to perform product development and present solution proposals for UPSs, which are essential equipment for data centers, on the basis of operating a system including entire peripheral equipment rather than optimizing the unit alone from the standpoint of avail- To customer’s load equipment ability and total cost of ownership of the entire electric- (a) Parallel redundant system ity infrastructure. At Fuji Electric, we are willing to further advance our technology so that we can contribute to Society 5.0 in which people will enjoy new values brought by X-Tech and to data centers that will play the key role there.

References (1) “Tier Classifications Define Site Infrastructure Perfor- STS mance”. http://www.mm4 m.net/library/(TUI3026E) TierClassificationsDefineSiteInfrastructure.pdf, (ac- cessed 2019-08-26). To customer’s load equipment (2) Yasumoto, K. et al. High-Efficient Power Supply Sys- (b) 2N system tems Utilizing 3-Phase 4-Wire Uninterruptible Power Systems. FUJI ELECTRIC REVIEW. 2019, vol.65, Fig.3 Configuration‌ examples of a parallel redundant system no.1, p.58-63. and 2N system (3) Sato, A. et al. “UPS7300WX-T3U,” Large-Capacity UPS Using SiC Hybrid Modules for North America. cooperation with DC operators and build UPS systems FUJI ELECTRIC REVIEW. 2017, vol.63, no.1, p.63-65. by not only optimizing the equipment delivered from (4) Yasumoto, K. et al. “UPS7000HX Series” and Fuji Electric but also optimizing the DC as a whole. “UPS6000DX Series,” Using Lithium Ion Batteries. Incidentally, Fuji Electric provides a function to FUJI ELECTRIC REVIEW. 2018, vol.64, no.4, p.221- enable control in a 2N system to synchronize the out- 226. puts from two UPS units.

5. Postscript

This paper described UPSs for hyperscale data

150 FUJI ELECTRIC REVIEW vol.65 no.3 2019

able high-efficiency operation during normal inverter normal during operation en high-efficiency to able added been also has function a control Furthermore, quantity with nor system. feeding power inverter UPS equipped mal 4-wire 3-phase, efficiency, high- a is which UPS7000HX-T4, the to functions ing feed power commercial continuous added has Electric power Fuji Therefore, stabilized operation. high-efficiency and achieve feeding will system feeding power commercial continuous a and system feeding inverter power the quality. lower will systems feeding power mercial com continuous and systems, feeding inverter normal using achieved been has supply power stabilized now, until Up much. used been not have power UPSs type feeding commercial continuous However, system. ing inverter normal a feed power commercial continuous a to system feeding from mode operating the change the server. to UPS the from directly power supply can that system “UPS7000HX-T4 our utilizing tem sys supply power high-efficiency a produced have we for (Si), silicon of rectifier the in diodes inverse-parallel instead (SiC), carbide silicon use that models includes line-up product our addition, In loss filter LC and loss switching reduce to level 3 to level 2 from voltage switching the changing by centers now, until data for UPS Up efficiency high achieved has Electric Fuji centers. data in used (UPS) systems power uninterruptible the of efficiency the improve to 1. * Commercial Power FeedingandQuantityControl Functions

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HAMADA, Ippei T C A R T S B A (1) ------.

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issue: Energy Solutions Contributing to Stable and Optimal Power Supply UPS I/O panel

AC AC Battery input output input

MC1

Rectifier

Chopper

Continuous Inverter rated thyristor Fig.1 Outer‌ view of UPS panel and I/O panel (UPS on left; I/O panel on right) MC4

MCCB3 Table 1 “UPS7000HX-T4” specifications Item Specifications Wiring 3-phase 4-wire Fig.2 “UPS7000HX-T4” main circuit configuration AC Voltage 400 V ±10% input Frequency 50/60 Hz Conventionally, the UPS panel and I/O panel have Power factor 0.99 (delayed) or higher been connected via an external cable. However, we Wiring 3-phase 4-wire have connected them using an inter-panel conductor Voltage 400 V ±10% connection. On-site construction can be simplified by Bypass Frequency 50/60 Hz input integrating the UPS panel and I/O panel. Further- 800% Bypass overload more, since there is no external cable connection, it is Single-cycle capability (thyristor short time) also visually appealing. Rated capacity 500 kVA Wiring 3-phase 4-wire 3. Continuous Commercial Power Feeding System Voltage 400 V Voltage tolerance <±1% During continuous commercial power feeding, Frequency 50/60 Hz power is supplied directly to the load from the commer- Frequency AC ±0.01 Hz (during self-oscillation) cial power supply, and the inverter is activated only to output precision charge battery and improve input power factor. There- Load power factor Rating 1.0 (0.7 lag to 1.0) fore, the load factor of the inverter is extremely lower Transient voltage 5% regulation <± for continuous commercial power feeding than for nor- Voltage waveform 2% or less (linear load), 5% or less mal inverter feeding. Furthermore, since the rectifier distortion factor (nonlinear load) is completely stopped, the efficiency during continuous Overload capacity 125% × 10 min.; 150% × 1 min. commercial power feeding exceeds 99% at the rated ca- Rated voltage 480 to 528 V pacity. Battery Floating charge 540 to 594 V voltage 3.1 Transferring control Dimensions W1,600 × D1,000 × H1,950 (mm) When power failure, serious failure or overcurrent Others Communication occurs during continuous commercial power feeding, MODBUS* interface the system transfers to the inverter so that it can sup- *‌MODBUS is a trademark or registered trademark of Schneider Automation, Inc. ply power at a stabilized power quality. Figure 3 shows the transferring control from continuous commercial power feeding. circuit-breaker (MCCB) for the battery. (1) Power failure transferring During continuous commercial power feeding, the In the event of power failure, the system transfers thyristor switch is continuously turned on, enabling commercial power to be supplied to the load. During *1: ‌Active operation refers to running an effective current to this operating, the rectifier is stopped and the inverter the thyristor by supplying reverse-phase current for the runs in the active operation so that it can charge the reactive current and harmonic current of the load cur- battery and improve the input power factor*1. rents.

152 FUJI ELECTRIC REVIEW vol.65 no.3 2019 : AC switch : Feeding : Charging Output voltage 3-phase [Normal] [Power failure] [Recovery]

Input voltage U phase Input current U phase No.1 INV current U phase No.2 INV current U phase (a) Power failure transferring No.3 INV current U phase No.1 bypass current U phase [Normal] [Failure] [Failure] No.2 bypass current U phase Normal UPS Normal UPS capacity No.3 bypass current > load capacity < load capacity U phase Battery voltage Power 3 parallel UPS failure After power failure, continuous commercial transfers to inverter power feeding feeding via all batteries Parallel (a) Power failure transferring waveforms off

(b) Failure transferring

Output voltage [Overcurrent 3-phase [Normal] [Overcurrent] release]

Input voltage U phase Input current U phase No.1 INV current U phase No.2 INV current (c) Overcurrent transferring U phase

No.3 INV current Solutions Contributing to Stable and Optimal Power Supply Energy U phase No.1 bypass current Fig.3 ‌Transferring control during continuous commercial power U phase No.2 bypass current issue: feeding U phase No.3 bypass current U phase to battery operation. When power is restored, it auto- Serious failure determination flag Serious matically transfers from the battery operation to nor- 3 parallel UPS failure 1 UPS suffers continuous failure, causing mal inverter feeding. It does not automatically return commercial power paralleling off and to continuous commercial power feeding. Therefore, feeding constant continuous commercial power feeding after a power failure, continuous commercial power via 2 normal UPSs feeding must be activated manually. The operating (b) Serious failure transferring waveforms principle of the system is to return to normal inverter feeding so that frequent transferring will not occur in Fig.4 ‌Transferring waveforms during continuous commercial the event that there are consecutive power failures fol- power feeding (with 3 parallel units) lowing the initial failure. During normal inverter feeding, a stabilized source of power can be supplied with- operation, the system transferring without instanta- out transferring during power failures. neous power interruption. During normal operation, (2) Failure transferring each UPS inverter runs active operation indepen- In the event that a UPS suffers a serious failure, dently. After a power failure, the system will transfer paralleling off will occur and a normal UPS will main- to parallel operation of the inverters using the battery. tain continuous commercial power feeding. If the UPS Figure 4(b) shows the transferring waveforms when detects overload, the system will transfer to bypass a serious failure occurs during continuous commercial power feeding. power feeding. When a serious failure occurs in the in- (3) Overcurrent transferring verter, the inverter is turned off, and after the bypass In the event of overcurrent, the system will trans- MC4 is turned on, the thyristor is turned off. After fer to bypass power feeding. When the overcurrent is shunting the commercial power supply to the thyris- resolved, it will return back to normal inverter feeding. tor and MC, the thyristor is turned off, ensuring that As mentioned above, continuous commercial power there is no waveform disturbance. feeding must be activated manually. Figure 4(a) shows the transferring waveforms when a power failure occurs during continuous commercial power feeding. Since the inverter is in a state of active

“UPS7000HX-T4” High-Efficiency UPS with Continuous Commercial Power Feeding and Quantity Control Functions 153 stopped. As a result, the loss of the standby UPS can 3.2 Design of peripheral equipment for continuous com- be reduced to approximately 200 W. As shown in Fig. mercial power feeding 5, during parallel operation of eight units, using quan- During continuous commercial power feeding for tity control can improve efficiency at light loads. paralleling systems, the load is shared according to the impedance of each UPS. Two type of power feed- 4.2 Quantity control method ing methods are available for the parallel UPS system: The number of units in operation needs to be con- power feeding through individual transformers or a figurable so that the UPS will not transition to bypass common transformer. power feeding with the overload capability is being In the case of the common transformer, the imped- exceeded even when the load rises sharply. The UPS ance is determined by the length of the cable up to the overload capability is 125% for 10 minutes and 150% point of paralleling. It is difficult to prepare all cables for 1 minute. The load factor of each UPS needs to be at the same length. As a result, there is generally a 150% or less during load spikes. In a parallel redun- 6 to 20 m difference in length, and this impacts load dant system (8 units × 500 kVA) with a system capac- sharing, since it is dependent on cable length. There- ity of 3,500 kW, 3,500/(1.5 × 500) = 4.7 indicates that fore, a balance reactor is required for the bypass circuit the minimum number of units in operation should be 5. of the UPS to balance load sharing. In the case of in- On the basis of the minimum number of required dividual transformers are used, the load is shared ac- units in operation, a load factor is determined accord- cording to the combined impedance of the transformer ing to the increase in efficiency before and after chang- and cable impedance. ing the number of units. In particular, the load factor The variation in the percentage of impedance of is set to approximate 70% when the load increases and Fuji Electric mold transformers is less than +1.5% to approximately 45% when the load decreases. -1.0%, relative to the average value. Furthermore, the The system comes with a function for smoothening impedance ratio of the cable to transformer is about an the operation integration time of each UPS; the UPS order of magnitude smaller. with the shortest total operation time becomes the next In the worst case scenario, the load sharing was to operate and the UPS with the longest total opera- ±5% when connection was made with the transformer tion time becomes the next to turn off. and cable impedance in ascending order. To deal with this, the ratings of equipment, such as transformers, 4.3 Transferring control during quantity control cables and circuit breakers, have a tolerance of ap- In the event of power failure of the input power proximately 5%. supply, overload or serious failure, the system will ba- sically transfer from quantity control to all-unit opera- 4. Quantity Control for Normal Inverter Feeding tion automatically. After confirming the soundness of Systems the system, operators can manually transfer to quantity control at their own discretion. 4.1 Standby UPS loss reduction and quantity control ef- For example, if a power failure occurs while oper- ficiency characteristics ating 5 units, the 5 units will instantly transfer to bat- When the no-load loss of a UPS can be smaller in tery power. The 3 standby units are put into parallel standby mode during quantity control than in normal operation after about 3 seconds. Furthermore, if there operation, operational efficiency can be improved. On is a serious failure in 1 of the 5 units and only 4 units the other hand, the battery needs to be continuously are operable, after about 13 seconds, all the UPS sys- charged for the UPS while it is in standby mode. In a normal inverter feeding system, the rectifier is controlled to have a power factor of unity. However, the 97 current of a fully charged battery is extremely small, 96 so it is not necessary that the power factor of the UPS 95 during standby mode be unity. Moreover, the loss of the 3-phase full-wave rectifier with diodes is extremely 94 2 unit operation smaller than that of PWM control, and therefore, the 3 unit operation 93 4 unit operation standby UPS performs 3-phase full-wave rectification 5 unit operation Efficiency (%) using the feedback diodes connected in inverse-parallel 92 6 unit operation 7 unit operation to the IGBTs without switching the IGBTs, main de- 91 8 unit operation vices of the rectifier. 90 The battery is charged using the chopper circuit. 0 500 1,000 1,500 2,000 2,500 3,000 3,500 The pulse control circuit is activated with the IGBTs of Load (kW) the inverter being turned off in preparation for parallel operation. This allows all cooling fans in the main Fig.5 ‌Efficiency characteristics for the number of units in op- circuit stack of the rectifier, chopper and inverter to be eration (2 to 8 units)

154 FUJI ELECTRIC REVIEW vol.65 no.3 2019 tems in standby mode will be put into parallel opera- the risk of transferring failure compared with the nor- tion. mal inverter feeding system. (3) Comparison of transferring control reliability dur- 5. Reliability of Normal Inverter and Continuous ing power failure Commercial Power Feeding Systems During a power failure, the normal inverter feeding system simply stops the rectifier without changing (1) Comparison of Failure In Time (FIT) during the inverter feeding. In contrast to this, the continu- single-unit operation ous commercial power feeding system requires that Table 2 shows a comparison between FIT*2 (normal the thyristor switch be stopped and that the inverter inverter feeding system is 100%) and transferring con- undergoing active operation be transferred to normal trol for normal inverter feeding systems and continu- inverter feeding. Therefore, there is a risk of failure in ous commercial power feeding systems. inverter operation transferring and thyristor switch- During continuous commercial power feeding, ing. As power failure occurs several times a year, it is since the number of rectifier components is large and necessary to recognize that there is considerable risk the rectifier itself is not activated, FIT will be smaller of transferring failure when using the continuous com- than during normal inverter feeding, enabling highly mercial power feeding system. reliable operation. When comparing the frequency of failure and (2) Comparison of reliability during failure power failures, the number of power failures is over- In the event of a failure, the normal inverter feed- whelmingly larger. Therefore, when utilizing continuing system will perform 4-step transferring control, ous commercial power feeding systems, which are sus- consisting of inverter turn-off, thyristor switch turn-on, ceptible to transferring failure during power failures, it MC turn-on and thyristor switch turn-off. In contrast is recommended that a highly reliable system, such as to this, the continuous commercial power feeding sys- dual redundant system, be used. tem performs 3-step transferring, consisting of inverter turn-off, thyristor switch turn-off and MC turn-on, 6. Postscript thereby reducing the number of transfers and lowering In this paper, we introduced our “UPS7000HX-T4” Energy Solutions Contributing to Stable and Optimal Power Supply Energy Table 2 ‌Comparison of normal inverter feeding system with high-efficiency UPS with continuous commercial power continuous commercial power feeding system feeding and quantity control functions. We have im- issue: Normal inverter Continuous commercial proved the operational efficiency of our 3-phase 4-wire Item feeding system power feeding system UPS7000HX-T4 by providing it with a continuous com- ○ 100% mercial power feeding function and a quantity control Comparison ◎ 90% of FIT* for Rectifier on, inverter Rectifier off, inverter on, function during normal inverter feeding. This en- single-unit on, Thyristor switch thyristor switch on hancement makes it possible to achieve high-efficiency operation off power management systems for data centers. In the future, we plan to continue contributing to society ○ 4-step Transferring Inverter off ⇒ ◎ 3-step through our high-efficiency and space-saving products. control thyristor switch on Inverter off thyristor during ⇒ failure ⇒ MC turn-on ⇒ switch off ⇒ MC turn-on References thyristor switch off (1) Yamagata, Y. et al. “UPS 7000HX Series” of High- Efficiency, Large-Capacity UPS Products Using AT- Transferring ◎ 1-control ○ 2-control control Rectifier on off Thyristor switch on off NPC 3-Level for Data Centers. FUJI ELECTRIC during → → (Continuous inverter Inverter active operation power REVIEW. 2012, vol.58, no.4, p.207-211. failure operation) → Inverter feeding (2) Sato, A. et al. “UPS7300 WX-T3U,” Large-Capacity *‌Cooling fans are excluded because they are redundant. UPS Using SiC Hybrid Modules for North America. FUJI ELECTRIC REVIEW. 2017, vol.63, no.1, p.63-65. *2: ‌FIT (Failure in time) is an indicator of the product fail- (3) Yasumoto, K. et al. High-Efficient Power Supply ure rate, corresponding to the average number of failures Systems Utilizing 3-Phase 4-Wire Uninterruptible per billion (109) hours of operation. 1/109 (failures per Power Systems. FUJI ELECTRIC REVIEW. 2019, hour) corresponds to 1 FIT. vol.65, no.1, p.58-63.

“UPS7000HX-T4” High-Efficiency UPS with Continuous Commercial Power Feeding and Quantity Control Functions 155 Testing Equipment Contributing to Quality Improvement and Environmental Impact Reduction of High-Capacity Power Electronics Equipment UMEZAWA, Kazuyoshi * YAMADA, Toshiya * CHIDA, Yukihiro *

ABSTRACT

The recent increase in capacity of power conversion systems has made it necessary to conduct conformity tests to meet the power supply quality stipulated by international and Japanese standards or required by customers. Efficiently performing testing under a variety of conditions can require a power as high as 1.5 MW, and power saving is needed. It is also necessary to completely protect electrical equipment from the impact of power fluctuations. To overcome these challenges, we have developed and deployed testing equipment capable of power regeneration to efficiently perform conformity testing and reduce power consumption during testing. The testing equipment helps shorten product testing periods, improve quality, and reduce environmental load.

1. Introduction test items and electrical specifications (voltage level, 3-phase wire, frequency) need to be supported in accor- Power conversion systems such as uninterruptible dance with the differing types of equipment undergo- power systems (UPSs) are used in data centers, semi- ing testing. Furthermore, when testing electrical char- conductor manufacturing plants, and other facilities acteristics, approximately 1.5 MW of power is required, that require a high degree of power quality and do not which is equivalent to the power consumption of 400 allow even momentary power outages. Power conver- general households. In order to comply with measures sion systems such as power conditioning systems (PCS) against global warming and the “Act on the Rational are also used to connect mega solar systems and other Use of Energy” (Energy Saving Act), we also made it renewable energy sources to power systems as stable possible to reduce power consumption during testing. power. These power conversion systems are required Moreover, it is necessary for testing equipment not to to have 1-MW class capacity to accommodate the in- impact on power receiving systems even in the event crease in capacity of data center servers and photovol- of large power spikes during testing so that the power taic power generation facilities. supplies of other electrical equipment are disturbed. In order to facilitate the practical application of these large-capacity power conversion systems, it is 2.1 Overall configuration necessary to conduct conformity tests in compliance Figure 1 shows the external appearance of the with the power supply quality stipulated by interna- high-capacity power electronics testing equipment, and tional and Japanese UPS standards. Therefore, Fuji Fig. 2 the overall configuration. The AC/DC converter Electric has developed testing equipment that complies (grid connection panel) converts AC power from an AC with the standards of large-capacity power electronics power receiving system into DC power and then sup- equipment. This enables testing of 1-MW class products under various conditions (AC input, storage battery input, load), thereby greatly contributing to product quality improvement. In this paper, we will introduce large-capacity power electronics testing equipment using UPS as a testing example.

2. Features of the Testing Equipment

In order to efficiently test large-capacity power conversion systems under standard-compliant test conditions (AC input, storage battery input, load), various

* Power Electronics Systems Energy Business Group, Fuji Electric Co., Ltd. Fig.1 High-capacity power electronics testing equipment

156 Power High-capacity power electronics High-capacity power testing equipment conversion system Signal 200- (testing target) (automatic control) Grid connec- 750 V DC Simulated 480 V AC V, A tion panel system panel AC/DC DC/AC UPS Input 270- Simulated storage 780 V DC V, A Integrated battery panel control panel DC/DC Battery 200- POD Output Simulated 480 V AC V, A load panel DC/AC Input DC Out- PLC put

Test information Data acquisition PC Instrument control Instrument

Fig.2 Overall configuration plies to the three panels characterized by the following Table 1 ‌Specifications of high-capacity power electronics testing simulated functions: equipment (a) Simulated system panel that generates voltage Panel Specifications in simulation of system voltage Capacity 750 kVA × 2 in parallel (b) Simulated load panel that controls power and Voltage range 200 to 480 V AC simulates load characteristics Connection 3-phase 3-wire / 3-phase 4-wire, (c) Simulated storage battery panel that simulates method delta / star Voltage toler- storage battery characteristics within ±0.1% Simulated ance Furthermore, the testing equipment comes with system Voltage distor- within 1% an integrated control panel for performing processing, panel / tion factor

simulated Solutions Contributing to Stable and Optimal Power Supply Energy such as setting various test modes and issuing com- Frequency load panel 50/60 Hz±10% mands to power conversion systems to activate specific range issue: Load adjust- test states. Test modes can be selected on the touch 0.5 kW / 0.5 kVar ment unit panel, and the fluctuation level and time can be pre- Delay load, lead load, active cisely set for voltage, current, power, frequency and Load function load, rectifier load, unbalanced other test items. The programmable logic controller load (PLC) installed in the control panel can perform opera- Capacity 500 kW × 3 in parallel tions in conjunction with other grid connection panels, Voltage range 270 to 780 V DC simulated system panels, simulated load panels and Simulated Voltage ripple within 1% storage bat- simulated storage battery panels. Current re- tery panel 20 ms or less sponse time Battery func- 2.2 Electrical specifications Battery charging / discharging tion Table 1 shows the specification of the testing equipment. It can handle up to 1.5 MW, and electrical connections can be configured with 3-phase 3-wire and However, with our testing equipment, testing can be 3-phase 4-wire connections and load connections at 200 performed at reduced power receiving of 0.25 MW, just to 480 V AC, 50/60 Hz. The simulated storage battery 1/6 of the load consumption, by utilizing the power can handle up to 1.5 MW at 270 to 780 V DC. The in- conversion systems with power conversion flow shown tegrated control panel can be used to change the level in Fig. 3. of the AC voltage and the electrical connection of the This power conversion flow converts the received 3-phase 3-wire and 3-phase 4-wire connections. Fur- AC voltage into DC via the grid connection panel, thermore, transformer tap selection switching, 3-phase and then circulates the DC power by linking the test- wiring delta connections and star connection selection function simulated system panel, simulated storage switching can be carried out using simply the touch battery and simulated load panel to the DC power, panel in accordance with the electrical specifications of achieving a significant energy savings. Each panel op- the equipment undergoing testing. erates as follows: (a) In the simulated system panel, the power from 2.3 Achieving high-capacity testing for small-capacity the DC link is converted to AC using the DC/ power reception AC converter, and the transformer voltage tap Typically, power receiving of 1.5 MW is required is switched so that the voltage complies with the to test 1-MW UPS when overload testing is included. electrical specifications of the equipment under

Testing Equipment Contributing to Quality Improvement and Environmental Impact Reduction of High-Capacity Power Electronics Equipment 157 AC input Equipment under testing (UPS) AC output Energy flow Power receiving

Grid connection panel DC output Integrated control panel

Voltage tap Voltage tap Delta / star Delta / star connection connection

PLC

Optical Optical Optical Optical communi- communi- communi- communi- cation cation cation cation

PLC

Communications System voltage command Storage battery voltage command Load power command DC link

Simulated system panel Simulated storage battery panel Simulated load panel

Fig.3 Configuration of high-capacity power electronics testing equipment

testing. tion route is circulated in the DC link circuit of the (b) In the simulated storage battery panel, the testing equipment, thereby preventing power from power from the DC link is converted to AC us- flowing through systems that affect other equipment. ing the DC/AC converter, and the DC voltage for As a result, power receiving and peripheral electrical simulating the storage battery is generated by equipment are not impacted even when performing the AC/DC converter after being transformed by transient characteristic testing, such as sudden load the transformer. fluctuation and power failure recovery testing. (c) In the simulated load panel, the power from the DC link is converted to AC using the DC/AC 2.5 Flexible test configuration converter so that the AC voltage can follow and Two PLCs are installed in the integrated control link with the output voltage of the equipment panel for controlling the testing modes. This makes it under testing. possible to configure a 0.75-MW testing system charac- (d) In the integrated control panel, the conversion terized by the standalone operation of a power conver- systems (a) to (c) are integrated to perform con- sion system (0.75 MW) and a 1.5-MW testing system trol based on the testing mode, and the power that runs two 0.75-MW power conversion systems in output from the UPS is set according to the load parallel by linking with the PLCs. Moreover, in the power command. 0.75-MW testing system, two separate pieces of equipment can be tested at the same time, thereby improv- 2.4 System stabilization during large power fluctuation ing efficiency. In large-capacity 1-MW tests, the sudden load fluctuation test and power failure recovery test gener- 3. High-Capacity Power Simulator Technology ate power fluctuation. As a result, the system voltage will fluctuate due to fluctuation in the received power 3.1 Simulated system simulator functions when there is no power regeneration equipment, and The simulated system panel supports three com- this creates the problem of impacting other electrical binations consisting of a single-phase inverter and equipment and test lines connected to the same power single-phase transformer to generate the voltage that receiving side. In contrast to this, when there exists simulates the system with the DC/AC converter. The a power regeneration equipment for AC distribution, connection method on the secondary side of the trans- there will be no inducement of fluctuation in there former output can be switched to a 3-phase 3-wire ceived power. However, voltage fluctuation will occur delta connection or a 3-phase 4-wire star connection in AC distribution systems that make up the regen- using an electromagnetic contactor. In addition, vari- eration route due to fluctuations in the phase of the AC ous voltages ranging from 200 to 480 V can be output current. This creates a problem of impacting the elec- with tap switching. This has made it possible to con- trical equipment in the circuit system. duct tests that comply with various voltages and con- Therefore, to solve these problems, we designed nection method in Japan and abroad. the system so that the power in the power regenera- High-capacity power electronics test equipment

158 FUJI ELECTRIC REVIEW vol.65 no.3 2019 can perform highly reproducible tests, including not This has made it possible to conduct tests that comply only standard tests, but also on-site ground-fault and with storage batteries of various cell number. short-circuit trouble reproducibility tests. For exam- With regard to the charge and discharge character- ple, in order to reproduce instantaneous voltage drops istics of storage batteries, battery voltage is high when such as 1-wire ground faults or 2-wire short circuits the remaining battery capacity is large, but low when due to lightning damage, unnecessary current genera- the remaining battery capacity is small. When test- tion must be prevented during sudden voltage fluctua- ing a UPS, it is necessary to verify operation when the tion. Therefore, the test equipment is designed to use storage battery has been charged to a full state, as well a transformer that does not generate an inrush excit- as operation when battery capacity is degraded to the ing current not to impact on test characteristics. The point of reaching the operational limit of the UPS. If voltage level and phase of the waveform to be repro- an actual storage battery is used, it will be necessary duced are set to be test setting parameters. The soft- to keep charging and discharging the battery continu- ware installed in the control device of the simulated ously for several hours to prepare the desired state due system panel and the system circuit model are used to the high battery capacity. In contrast to this, our to calculate the line impedance and the phase volt- high-capacity power electronics testing equipment can age drop characteristics. Instantaneous voltage drop start testing immediately from the state that the bat- waveforms can be reproduced by the power conversion tery is charged almost to full capacity or from the bat- system controlling the simulated system panel using tery capacity is degraded by simply setting the initial the corresponding specified system voltage commands. value of the storage battery voltage.

3.2 Simulated load simulator functions 4. Specific Test Examples The circuit configuration of the simulated load panel is exactly the same as that of the simulated sys- 4.1 Applicable test items tem panel. The only difference is that control target Table 2 shows examples of tests that can be perfor the simulated system panel is voltage, whereas that formed with the testing equipment. for the simulated load panel is electrical power. After setting basic information, such as the volt- There are two types of load characteristics, age and capacity of the equipment under testing and namely, passive load mode and active load mode. Pas- simply selecting the test mode, electrical testing can be Solutions Contributing to Stable and Optimal Power Supply Energy sive load mode reproduces passive loads, such as those performed for JEC and IEC standard compliant power issue: for resistors, reactors and capacitors. The passive load conversion systems using the simulator functions de- operates with power proportional to the voltage; there- scribed in Chapter 3. fore, the current is proportional to the output voltage of the UPS under testing. Active load mode reproduces 4.2 Example of reproducing 2-wire short circuit active loads, such as those of the switching power sup- UPSs are tested in compliance with the JEC-2433 plies of high-power factor converters used in modern and IEC standards. In actuality, disturbance phenom- server power supplies. The active load keeps constant ena that are not defined in the standards can occur power consumption, and the current is increased to after installation in the field. For example, the stan- keep the electric energy constant when the output volt- dards define a UPS test in which power is cut offfor age of the UPS under testing drops. It is also possible all phases, but in actuality, short circuiting between to test the mixed mode of both loads specified in the lines due to lightning strikes and other causes will IEC standard. also happen. Fuji Electric’s UPS comes with a func- By setting the load characteristic mode, fluctuation tion for storing voltage and current waveforms at the level and fluctuation time as test setting parameters, time of failure. Using the power system model simula- the load characteristics are calculated using the load tion with stored waveforms, analysis is performed to circuit model and the software installed in the control device of the simulated load panel. The power conver- Table 2 Example of testing items sion system of the simulated load panel controls the Target simulator Test item power to reproduce the target load waveforms accord- ◦ Voltage: Slow change, sudden ing to the corresponding specified load power - com change, instantaneous drop mands. Simulated system ◦ Frequency: Slow change, sudden change, follow-up ◦ Reverse power flow, reverse phase 3.3 Simulated storage battery simulator functions Active load, passive load, rectifying The simulated storage battery panel generates AC Simulated load load, unbalanced load, load fluctuation, voltage using a DC/AC converter. After the voltage is overload Battery discharging, charging changed by the transformer, a DC voltage for simulat- Simulated storage ◦ Battery test function battery ◦ ing a storage battery is transformed using the AC/DC ◦ Battery abnormality converter. Various voltages ranging from 270 to 780 V DC can be output with transformer tap switching.

Testing Equipment Contributing to Quality Improvement and Environmental Impact Reduction of High-Capacity Power Electronics Equipment 159 discover the line voltage when a short circuit occurred, the level and timing (phase) of the short circuit, and the amount of the load. On the basis of the analysis results, the actual short circuit phenomena can be V/div) reproduced by selecting the 3 items on the test mode setting screen of the testing equipment: short-circuit lines, level, and phases (see Fig. 4). In our testing equipment, resistance preparation and recombination work are not required, unlike conventional systems that use resistances via a circuit UPS input voltage (10 0 breaker. Although conventional methods cannot accurately reproduce the phase at which a short circuit (a) At time of on-site lightning strike occurs, our testing equipment can reproduce it at the same exact phase with high accuracy. For the above reasons, tests conventionally require about 2 weeks to reproduce and analyze causes, but using our test- V/div) ing equipment takes just one day to reproduce the phenomena, since testing only requires connecting the UPS and setting conditions on the touch panel. Figure 5 shows a comparison of the waveform at the time of the actual short-circuit incident with the waveform re-

produced by the testing equipment. It also reproduces UPS input voltage (10 0 the residual voltage level of each phase, the generated phase and the vibration phenomenon of the voltage at (b) At time of reproduction via testing equipment

Fig.5 Two-wire short-circuit waveform

the time of the short circuit.

5. Postscript

In this paper, we introduced testing equipment that contributes to quality improvement and environmental impact reduction of high-capacity power

Short-circuit electronics equipment. The testing equipment can Phase lines perform highly accurate reproduction tests and stan- Level dards compliant tests for high-capacity products of the 1-MW class while achieving energy savings. Moreover, it contributes to shortening test periods and improving quality. In the future, we plan to continue to develop and improve the quality of power electronics product Fig.4 Touch panel setting screen technologies.

160 FUJI ELECTRIC REVIEW vol.65 no.3 2019

(1) as follows: are maintenance equipment in issues important most the Maintenance, Plant of Institute Japan the of nance 2. continuous improvementinplantsandfactories. conducting and through solutions providing issues, maintenance identifying equipment electrical op timizing for solution support a is which Service,” agement Man Equipment “Comprehensive our this do introducing will by We energy. of source stable a supplying in essential equipment electrical quality of maintenance the and improving for technologies maintenance be usedinnewtypesofdataanalyticssystems. can data collected the since maintenance, smart of era the commence helped has This data. of types lectible uncol previously collect to possible it made has (IoT) secu rity. and safety ensure to technologies maintenance equipment improve to together working been have ers manufactur and owners equipment Therefore, duties. management and social its fulfilling of incapable pany com the making and image company the impairing as such risks managerial to lead can accidents Equipment equipment. production of efficiency and operation ble 1. * Supporting OptimizationofEquipmentMaintenance

Electric Co.,Ltd. Power Electronics Systems Industry Business Group, Fuji Group, Business Industry Systems Electronics Power “Comprehensive EquipmentManagementService” h rcn dvlpet f h Itre o Things of Internet the of development recent The sta the for essential is maintenance Equipment codn t te netgtv rpr o mainte on report investigative the to According equipment our describe will we paper, this In Challenges inManagingElectricalEquipment Introduction conducting continuousimprovement,intermsofcustomers’businessandequipmentmanagement. and solutions, their providing issues, identifying involving maintenance, equipment optimal for support delivering by equipment of management and operation secure and safe the to contribute services Our management. cost to check daily a from covering equipment, of reduc management and as operation the well optimizing by as costs maintenance times, equipment ing repair shortening and malfunction preventing by operation equipment stabilizing at aimed Services, Management Equipment Comprehensive provides Electric Fuji equipment. the of management prehensive com also but troubleshooting, and maintenance equipment only not cover that services support seeking are owners ure ehoois o tp eurne n peet fail prevent and recurrence stop to Technologies Equipment maintenance is essential for stable operation and efficiency of production equipment. Equipment equipment. production of efficiency and operation stable for essential is maintenance Equipment FUKUSHIMA, Soji T C A R T S B A ------oioig n danss f alrs u t degrada to due failures of diagnosis and monitoring through troubles potential preventing for technologies and recurrence preventing for measures develop to ing but alsocomprehensivemanagement oftheequipment. troubleshooting, and maintenance equipment only not that cover that services support seeking are customers equipment own However, contracts. maintenance of form the in customers its for manufactured it products 3. plans andyearlymaintenanceplans. to and maintenance long-term policies to medium- manage and create higher-level on based policy tenance (5) productivity andefficiency. improving of challenge managerial important the have (4) continue tooperatewithoutaccidents. can equipment that so costs maintenance streamline to is challenge The goals. volume production achieve preferentially to time of periods long for operated are (3) pertise andskillsoftheirpredecessors. next- the secure and ex the inherit can train they that so personnel of generation to how is challenge The older. getting are maintenance plant for needed skills (2) tion. The challenge is to use the results of troubleshoot of results the use to is challenge The In order to provide the Comprehensive Equipment Comprehensive the provide to order In the for services providing been has Electric Fuji Management Service” main equipment an formulate to is challenge The products sell and manufacture that Businesses they because aging are facilities and Equipment and expertise the have who personnel Experienced Overview of“ComprehensiveEquipment Maintenance managementcycle Improved productivityandefficiency Supporting agingequipment Methods fortrainingandsecuringpersonnel *

- - 161 - - - -

issue: Energy Solutions Contributing to Stable and Optimal Power Supply Management Service, it is important to secure the fol- ment Management Service on the basis of a process lowing technologies and human resource capabilities flow that includes identification of issues, resolution of based on customer trust earned through many years of issues and continuous improvement according to the experience: needs of the equipment to be managed and the opera- (a) Service products that capture on-site customer tions of the customer. Table 1 shows equipment man- and service needs agement issues and solution measures. (b) Technologies that combine on-site diagnosis and remote monitoring of equipment Table 1 Equipment management issues and solutions (c) Equipment maintenance consulting that ana- Issue Solution lyzes customer operations, identifies issues Equipment in general Comprehensive equipment ◦ To visualize the overall picture diagnosis and provides solutions of equipment installation ◦ Comprehensive equipment (d) Improvement in specialized skills and range of ◦ To review equipment mainte- diagnosis service skills of Fuji Electric service engineers nance ◦ To make an equipment invest- (e) Change in awareness of service engineers ment plan from “things” to “experiences” ◦ To ensure social responsibility and safety (f) Centralized management and utilization of Maintenance policy Maintenance plan customer information and remotely monitored ◦ To perform maintenance ac- ◦ Maintenance plan data by consolidating contact centers acting as cording to the importance of ◦ Maintenance according equipment to the state of stress and contact points for Fuji Electric products ◦ To prevent failure and recur- quality of equipment rence ◦ Equipment diagnosis of 3.1 Purpose of “Comprehensive Equipment Management ◦ To stabilize operation of aged individual units equipment Service” Aged equipment Equipment replacement As shown in Fig. 1, equipment management opera- ◦ To renew aging equipment ◦ Equipment renewal tions start with the formulation of maintenance strate- ◦ To introduce the latest tech- ◦ Deployment of quality im- nologies at renewal proved equipment gies and plans, and cover a wide range of areas, includ- ◦ To improve equipment quality •Power supply stabilization ing maintenance implementation, maintenance data ◦ To improve equipment avail- •Energy savings, etc. management, equipment management, and mainte- ability nance personnel education and training. Furthermore, Equipment abnormality Equipment monitoring ◦ To reduce downtime and re- ◦ Introduction remote moni- the service aims at stabilizing equipment operation by start time toring system preventing failure and shortening repair times, as well ◦ To improve maintenance •Operation monitoring as reducing equipment maintenance costs by optimiz- ◦ To ensure social responsibility •Remote maintenance and safety •Degradation diagnosis, etc. ing the operation and management of equipment in Maintenance management Maintenance management day-to-day operations ranging from daily inspections to ◦ To manage maintenance per- plan cost management. sonnel more efficiently ◦ Introduction of equipment ◦ To manage maintenance parts management support tools more efficiently •O&M support 3.2 Provision of the “Comprehensive Equipment ◦ To use maintenance data ef- •‌‌Wearable remote support, Management Service” fectively etc. ◦ To secure and train mainte- ◦ Education and training Fuji Electric provides the Comprehensive Equip- nance personnel support

(1) Optimization of equipment operation and management (reduction of equipment Aim: Support for optimizing equipment maintenance Customer maintenance costs) for plant and factory electrical equipment management value issues (2) Stable operation of equipment (prevention of failure, reduction of repair time)

Customer equipment to be managed Development of maintenance strategies and maintenance plans Power receiving ○Daily inspection and distribution ○Regular inspection Implementation equipment of maintenance ○Sudden trouble response Transformer Cast resin Circuit Switchboard Drive ○Work management transformer breaker control device ○Equipment supplier Management of support Power supply Monitoring maintenance data ○Document equipment and control management Equipment ○Ledger management Management of ○Work management DCS Customer business axis equipment Uninterruptible Gas ○Part management power systems (UPS) analyzer ○Cost management Implementation of Production Auxiliary ○Disaster prevention ○Air-conditioning system maintenance education equipment Environmental and training equipment equipment ○ ○Lights monitoring equipment

Fig.1 Purpose of “Comprehensive Equipment Management Service”

162 FUJI ELECTRIC REVIEW vol.65 no.3 2019 (1) Identification of issues for analyzing the collected data. We consult with customers and identify issues The O&M service platform provides the operation, through comprehensive equipment diagnosis that in- maintenance and analytic management functions de- cludes risk assessment. Some of the issues we identify scribed in Section 5. A common monitoring user inter- include issues that arise on the customer side when face (UI) for equipment to be managed by the service is formulating equipment maintenance plans, issues in- provided as a template. volved in the implementation of maintenance plans, The O&M service includes the following four ap- issues related to performance management and issues plications: related to maintenance personnel, maintenance parts (a) Centralized remote monitoring for VCBs and maintenance cost management. (b) Partial discharge monitoring (on-site) for (2) Resolution of issues high-voltage equipment Depending on the types of issues identified, we pro- (c) Remote monitoring for Data centers (including pose solutions for (1) maintenance plans, (2) equipment those under development) replacement, (3) equipment monitoring and (4) mainte- (d) Remote monitoring for storage batteries nance management plans as shown in Table 1. These applications enable users to select equipment- (3) Continuous improvement specific information for determining abnormal signs, We continuously revise maintenance plans by consisting mainly of the operating information and evaluating and analyzing the effect of adopted solu- alarm information of equipment under management, tions using collected data. We also implement other and then define and configure the UI for monitoring initiatives for improvement such as revising inspection and diagnosing the information using the template. cycles, improving management techniques and renew- ing equipment. 5. Integration and Analysis of Operating Information and Maintenance Information 4. System for Implementing the Service As shown in Fig. 3, the O&M service platform has Figure 2 shows the system configuration of the functions to support the operation management, main- Comprehensive Equipment Management Service. The tenance management, and analytical management Comprehensive Equipment Management Service con- tasks defined in ISO 18435 (O&M integration model). Solutions Contributing to Stable and Optimal Power Supply Energy sists of several components, including field devices, an The platform integrates and analyzes maintenance issue: IoT platform, an operation and management (O&M) information collected from the target products. The in- service platform(1),(2) and O&M service applications. formation includes operating information and worker- The IoT platform consists of an edge controller that job related inspection information and failure informa- collects field data sent from field devices, a server sys- tion. tem that provides an execution environment for service applications, communication functions for connecting 5.1 Operation management functions the platform components and a data analytics system The operation management functions collect and store the operating information of equipment under management in the field. The information of the Energy Operation equipment is obtained from the edge controller and management optimization Equipment management

O&M service applications O&M service platform Operation Analysis Maintenance IoT service applications management*1 management*2 management*3

Operation plan Data analytics Maintenance plan Data analytics

AI Server system

IoT platform Data Feedback collection Data analysis Operation Maintenance inspection monitoring and abnormality recovery Edge controllers

Operating Maintenance information information

Field *1: Cloud remote monitoring system devices *2: AI engine and BI (business intelligence) tools *3: Equipment management support system

Fig.2 System Configuration Fig.3 Functional diagram of O&M service platform

“Comprehensive Equipment Management Service” Supporting Optimization of Equipment Maintenance 163 stored in the cloud server system via the Internet and operation management functions. For example, it is monitored remotely by the O&M service applications. possible to identify equipment that had a failure by comparing (1) through (4) in the figure (points where 5.2 Maintenance management functions productivity drops significantly below the plan) with The maintenance management functions manage the maintenance information [see Fig. 4(b)] making up maintenance information, such as the inspection and the failure occurrence state. failure information input by the equipment manage- Figure 4(c) shows the inspection information of ment support system. In particular, this includes in- Equipment A as one example of the maintenance infor- formation on the location of installation based on the mation obtained from the maintenance management equipment ledger (installation year, manufacturer in- functions. By analyzing the trends of the inspection formation, maintenance contact information, consum- information and failure occurrence state for Equip- ables list, etc.), as well as information on inspection ment A, it can be seen that the data of inspection item plans and results, failure history and countermeasure 1 becomes smaller before the failure of Equipment A, records, replacement parts inventory status, and main- whereas the data of inspection item 2 tends to grow tenance records. larger. By reflecting the shortening of the inspection period for the data for inspection item 1 and the data 5.3 Analysis management functions for inspection item 2 obtained from the analysis results The analysis management functions integrate op- into the inspection plan, It becomes possible to improve erating information and maintenance information. the accuracy of failure detection and predict failure in After this, the functions analyze and evaluate data re- advance. Furthermore, it also becomes possible to pre- lated to operating, status and trend monitoring; iden- vent failures in advance and improve equipment avail- tification, diagnosis, prediction and optimization; and ability by implementing planned maintenance before risk, impact and environmental burden. failures occur. The results of the analysis and evaluation are re- Figure 4(d) shows the operating information before flected to operation plans and used for revising and and after the failure of Equipment A. By statistically reviewing maintenance plans. This makes it possible analyzing this information, it is possible to discover to reduce equipment maintenance costs by optimiz- correlations between newly acquired sets of operation ing equipment operation and management, prevent data. Figure 4(e) shows the data correlation of all oper- failures through stable operation of equipment and ating information of Equipment A following statistical shorten repair times. analysis. In this example, we can see that before the failure occurs the data shows a value far from the nor- 6. Introduction Examples mal correlation. Therefore, by setting a threshold value and moni- 6.1 Availability improvement toring it carefully for the operating information of Figure 4 shows an example of improving availabil- Equipment A determined by the data correlation, it is ity by integrating operating information and mainte- possible to detect abnormalities in advance, avoid ab- nance information using the O&M service platform. normal equipment stoppages and improve equipment The operating information includes production availability. records [see Fig. 4(a)], which are acquired from the

(a) Production records (d) Equipment A operating information (e) Equipment A operating information data correlation 4,200 (1) 2,000 5,200 (1) 3,200 1,500

Operating 2,200 1,000 information (1) (2) (3) (4) 1,200 500 200 200 0 2/1 2/15 3/1 3/15 3/29 0:00 0:08 0:16 0:24 0:32 0:40 0:48 0:56 0 200 400 600 800 1,000

(b) (c) Equipment A inspection information

No Equip- Failure information 420 ment (1) (2) (4) (1) A XXXXXXXXXXXXXXXXXX Maintenance 220 information (2) A XXXXXXXXXXXXXXXXXX (3) B XXXXXXXXXXXXXXXXXX 20 (4) A XXXXXXXXXXXXXXXXXX 2/1 2/15 3/1 3/15 3/29

Fig.4 Example of improving availability

164 FUJI ELECTRIC REVIEW vol.65 no.3 2019 Before introduction of remote monitoring service

Phone call Situation Call for CE Detailed Purchase of Delivery of Recovery reception ascer- CE transfer on-site replacement replacement parts work Completion tainment investigation parts

After introduction of remote monitoring service Call for CE 30 time reduction Situation Detailed CE transfer ％ Email Recovery ascer- remote Completion reception tainment investigation Purchase of Delivery of work replacement replacement parts parts CE: Customer engineer

Fig.5 Comparison of failure repair time before and after introduction of a remote monitoring service

6.2 Reduced repair time eration and maintenance management. Figure 5 shows a comparison of the failure repair The application of data analytics has achieved time over a period ranging from time of occurrence to some successful results, albeit still limited in useful- completion of repair when using the remote monitor- ness. Currently, it is primarily applied to the edge ing system. When a failure or sign of abnormality is controllers, but in the future, we plan to continue detected, the O&M service application sends an ab- developing applications in the cloud so that we can normality notification email. After receiving the noti- facilitate the integration of the information on opera- fication, Fuji Electric’s service engineers immediately tion and maintenance and evaluate and utilize a wide connect to the O&M service application to get a better range of information, such as long-term data. understanding of the situation, identify the cause and There is a high need for consulting in the field of arrange a response. In some cases, the time it takes to equipment maintenance. Therefore, we are offering detect the abnormality and complete the recovery has our Comprehensive Equipment Management Service been reduced by about 30% compared to before the in- as a solution that utilizes our expertise to provide a Solutions Contributing to Stable and Optimal Power Supply Energy troduction of the system. variety of equipment maintenance services in close re- issue: lationship with our customers. The service contributes 7. Postscript to safe and secure equipment operation and management by reducing maintenance costs, preventing fail- In this paper, we introduced our “Comprehensive ures and shortening repair times. Equipment Management Service” as a solution that supports optimization of equipment maintenance. References Fuji Electric is developing its IoT solutions based (1) Yasukawa, Y. et al. New Value-Creating Solutions on the concept of “Small, Quick Start & Spiral-up” ac- Starting From IoT: Current Status and Future Outlook. cording to our catch-phrase of “Creating new value for FUJI ELECTRIC REVIEW. 2018, vol.64, no.3, p.103- our customers through use of field devices, analysis 108. and optimization technologies.” Among these solutions, (2) Yamada, T. et al. Overview of Fuji Electric IoT our equipment management solution is an IoT service Platform. FUJI ELECTRIC REVIEW. 2018, vol.64, application that incorporates various services that aim no.3, p.136-139. at optimizing equipment maintenance through analysis and management of information acquired from op-

“Comprehensive Equipment Management Service” Supporting Optimization of Equipment Maintenance 165 One-Stop Solution for Power Supplies of Large-Scale Facilities MURAGISHI, Takuro * TAKAHASHI, Jun *

ABSTRACT

The accelerating worldwide economy has required flexible and timely facility expansion in accordance with economic trends. Fuji Electric received an order of equipment such as switchboards for a newly constructed semiconductor plant as an engineering, procurement and construction (EPC) project. In the project, we proposed the “M-Qube” motor control center, and it was adopted owing to the flexible scalability and adaptability to specification changes. Furthermore, we also received an order for the power supply facilities, including cogeneration facilities as an EPC project, of a newly constructed assembly plant. We utilized a container package to reduce the size of the cogeneration facilities, while also decreasing total costs and supporting BCP.

1. Introduction

Fuji Electric’s power supply equipment mainly support the day-to-day operations of facilities such as factories, buildings, and data centers (DCs). C-GIS/GIS Monitoring device Digital relay In recent years, the use of power generation equipment and uninterruptible power systems (UPSs) has Power plant Super been increasing to respond to commercial power fluc- high tuation and failures due to weather anomalies and to implement a business continuity plan (BCP). Fur- Power generator thermore, there has been an increasing trend to order Super-high High voltage transformer power receiving and transforming facilities, power gen- voltage eration facilities and UPSs as a bundled set instead of G individually. As a result, this has created the need for one-stop support. In this paper, we will introduce our one-stop solu- Each building tion for the power supplies of large-scale facilities in … … Low Each Low response to current-day market needs. voltage floor voltage

2. Requirements of Power Supplies

Figure 1 shows the configuration of main power supply equipment in power supply systems. Power Switchboard Cast resin UPS, instantaneous supply systems receive super-high voltages or high transformer power failure voltage power at on-premises power receiving equip- countermeasure device ment. After stepping down the voltage and allocating it to buildings and floors, this system further steps Fig.1 Power supplies provided by Fuji Electric down the voltage and distributes it so that equipment can operates. It is necessary to properly select power important of these solutions involves redundancy*1 to supply equipment and units and operate them in close ensure stable power supply. In addition to this, how- connection. ever, the acceleration of the worldwide economy has Fuji Electric is providing its customers with optimal solutions by capturing the mega-trends surrounding *1: ‌Redundancy refers to the preparation of multiple compo- the power supplies shown in Table 1. One of the most nents with the same function or role for the components of a device or system, and to the placing such components in a state of standby ready to replace other compo- * Power Electronics Systems Energy Business Group, Fuji Electric Co., Ltd. nents upon failure.

166 Table 1 Power supply megatrends and needs partly because they are facing a shortage of supervi- Power receiving and sory engineers. Market Megatrend distribution equipment background needs 3. Examples of Data Centers (DC) ◦ Economic development in Southeast Asia ◦ Timely equipment In recent years, DCs have been increasing in scale Globalization ◦ Trade friction investment and there has been a growing trend regarding the leas- acceleration ◦ Spread of ◦ Flexible facility e-commerce scalability ing out and renting of individual buildings and floor ◦ M&A based spaces. DCs also need to maximize equipment invest- business expansion ment cost-effectiveness and support facility scalability Bundled equipment Declining birthrate ◦ ◦ ordering and availability. and aging Shortage in Automated population ◦ There are mainly three forms of DC usage, broadly the Japanese inspection Reduction in labor force ◦ Efficiency categorized as housing (collocation), hosting and cloud. working hours ◦ ◦ Maintenance free ◦ Lack of engineers In particular, in the case of utilizing housing to entrust ◦ Long-life products management of user servers, equipment investment Flexible facility Innovation Smart factories ◦ plans are largely influenced by the number of tenants ◦ scalability in production ◦ Use of robots ◦ Visualization and functional requirements. Plans regarding equip- technology ◦ Flexible production ◦ Automation ment installation and construction, as well as staged ◦ Failure prediction ◦ Automated construction work, need to be specified in great detail Learning functions diagnosis Spread of IoT ◦ AI Life expectancy with DC business operators. Faster ◦ ◦ Utilization of big diagnosis communication ◦ Fuji Electric received an order to supply DC power data Failure analysis speeds ◦ ◦ Spread of smart ◦ Optimization supply facilities for a certain business operator as an devices control EPC project*2. The facilities includes 77-kV power ◦ High efficiency supply equipment, gas turbine power generation equip- Environmental ◦ Reduction of ◦ Environmentally ment, UPS and a site monitoring system. Figure 2 performance environmental resistant products burdens shows an overview of the facilities. On the basis of our ◦ Redundancy past achievements and experience with EPC projects, Improvement ◦ Cogeneration Solutions Contributing to Stable and Optimal Power Supply Energy ◦ Abnormal weather we compiled the requirements, created a design and in security ◦ Emergency power ◦ BCP equipment production plan, notified relevant govern- and safety generation facilities issue: ◦ Resilience performance ◦ Instantaneous drop ment agencies and offices, performed on-site construc- countermeasures tion and adjustment tests, and carefully planned and shortened the up and down trends of business cycles in all industries, resulting in the need for flexible and Standby power 66-kV super-high power Standby power timely facility expansion in accordance with the state generation receiving and generation equipment distribution equipment equipment of the economy. Furthermore, one-stop solutions are 5,000 kVA 50 MVA × 4 5,000 kVA becoming more popular as services ranging from maintenance and inspection to labor-savings of construction management, including budget control, design ar- Emergency Emergency Emergency Emergency power power power power rangements, construction arrangements, and delivery generation generation generation generation facilities facilities facilities facilities time management. Along with this trend, comprehen- 5,000 kVA 5,000 kVA 5,000 kVA 5,000 kVA sive ordering of facilities is increasing to streamline 6-kV 6-kV 6-kV 6-kV business processes from equipment investment to op- substation substation substation substation eration. equipment equipment equipment equipment For example, the increasing size of DCs requires For For For For uninterruptible uninterruptible uninterruptible uninterruptible not only high quality and reliability, but also scalabil- power system power system power system power system server server air conditioner air conditioner ity of facilities according to demand without needing 3,500 kVA 3,500 kVA 500 kVA × 2 500 kVA × 2 to install all equipment during the initial construction stage. Semiconductor plants require facilities to 3,500 kVA × 8 sets 1,000 kVA × 4 sets be scalable and maintainable without stopping operations, while placing a heavy emphasis on quality Fig.2 ‌Overview of DC power supply facilities at business op- and the safety of maintenance workers. In assembly erator plants, factors related to both economics and BCP need to be considered. *2: ‌EPC is an acronym for engineering, procurement and Moreover, customers are tending to order facilities construction and consists of a series of processes includ- as a bundled set ranging from power receiving equip- ing the design, material procurement, production and ment to low-voltage equipment instead of ordering construction work during the construction of factories them individually as they did in the past, and this is and plants.

One-Stop Solution for Power Supplies of Large-Scale Facilities 167 carried out various inspections, enabling us to com- Therefore, M-Qube was adopted for the system to plete the project without delay. Fuji Electric is sup- have flexibility to accommodate the expansions and porting the operation of DCs by providing UPSs with changes of specifications.. The M-Qube complies with the highest level of efficiency, as well as other power international standard IEC 61439, Form 4b*3, improv- supplies characterized by standardized peripheral pan- ing safety for nearby workers in the event of an on- els, low running costs and high scalability. site accident. Moreover, the housing is constructed of nuts and bolts rather than welding, and therefore, it 4. Examples of Semiconductor Plants improves not only maintainability, but also shortens production times and simplifies disposal. As shown in Fuji Electric received an order for 22/6.6-kV Fig. 3, it is a cradle type module consisting of MCCBs switchboards, 22-kV cast resin transformers, low- and contactors (MC). The height of the module varies voltage control centers, central monitoring systems, depending on capacity, but the width is fixed. While and UPSs as an EPC project in the construction of a maintaining IP2X*4 protection even when the module new semiconductor plant for one of our customers. For is pulled out, it can safely and flexibly adapts to the ex- the project, we proposed the “M-Qube” motor control pansion and changes of specifications by changing the centers manufactured by Fuji SMBE (see Fig. 3), and combination of its modules. Furthermore, the maxi- the proposal was adopted as a solution to flexible scal- mum rated current on the panels is 5,000 A, enabling ability and adaptability to specification changes. large-capacity power transmission while allowing for Semiconductor production utilities typically in- flexible circuit arrangements, capacity changes and clude air conditioning, water supply, wastewater treat- scalability. ment, air pressure, exhaust and gas supply equipment. The power capacity, voltage, and existence of emer- 5. Example of Assembly Plants gency backup power supplies for a power outage in the facilities varies depending on the type of power supply. Fuji Electric received an order for the power sup- Furthermore, since innovation in semiconductor manu- ply facilities of a new assembly plant as an EPC facturing technology is rapid, production lines are fre- project. The facilities include 66-kV power receiving quently expanded, consolidated or abolished according and distribution equipment, 6.6-kV power distribution to the state of the world economy. Therefore, specifica- equipment, 6.6-kV cast resin transformers, a central tions often change significantly between design phase monitoring system, and cogeneration equipment. The and completion. In the past, a fixed-frame molded case cogeneration facilities shown in Fig. 4 and Fig. 5 utilize circuit-breaker (MCCB) would be installed in panel waste heat from hot water and steam produced when housings, making it difficult to flexibly respond to spec- operating electrical equipment and engine, further sav- ification changes in design and production. ing energy in the plant. The hot water produced by the cogeneration equipment is used after being cooled with the cold and hot Top frame water generator during the summer, while being supplied as-is to an external air conditioner during the winter. In addition, high-temperature engine exhaust Configuration of main circuit module gas is converted into steam using a heat recovery 1: MCCB only steam generator to use it in the drying process of coat- 100AF: 1-module ing lines in the plant. This use of exhaust heats has cradle type improved efficiency and is contributing greatly toen- 250AF: 2-module cradle type ergy savings in the plant. Up to 9 main circuit 400AF: 3-module When the 66-kV power receiving and distribution modules cradle type equipment detects a commercial power failure, it sends 630AF: 4-module cradle type a signal to the 6.6-kV power distribution equipment in 2: MCCB + MC the plant via the central monitoring system and transi- 2,200 mm 2,200 100AF: 1-module tion to fail-soft operation during the entire outage. Af- cradle type ter this, power is sent to important loads by controlling 250AF: 3-module cradle type the cogeneration equipment according to BCP. 400AF: 8-module fixed type 3: ‌Form4b refers to a structure in which input equipment, Monitor 630AF: 9-module * communications fixed type buses, output equipment, and output cable terminal com- unit compartment 3: ACB only partments are individually compartmentalized. 9-module 4: ‌IP2X indicates class 2 dust protection, but no guarantee Base ACB cradle type + control panel * regarding waterproofing. It is also known as “finger protection” and refers to a degree of protection that prevents Fig.3 Configuration “M-Qube” motor control center access to hazardous parts with fingers.

168 FUJI ELECTRIC REVIEW vol.65 no.3 2019 : Power supply circuit Normal power generator : Power supply circuit Normal power generator ○Use of hot water for air 66-kV commercial power 66-kV commercial power conditioning ○BCP power supply ○Use of steam for production Power outage G G

G G Power Power Power Synchronous input at power Hot Steam recovery water Synchronous input CB Synchronous input CB Heat … …

External air condi- Cutoff tioner

Cooling and Coating heating line Important load General load Important load General load Fig.5 ‌Cogeneration operation according to BCP (securing im- Fig.4 ‌Normal cogeneration operation (using hot water and portant power supply) steam) one-stop solution. Moreover, the cogeneration equip- When power is recovered, the 66-kV power receiv- ment is used not only to achieve energy savings at the ing and distribution equipment can be synchronized plant, but to also provide important functions for BCP with the commercial power supply using a synchroni- support. zation test device to initiate operation without inter- Solutions Contributing to Stable and Optimal Power Supply Energy ruption. 6. Postscript issue: The cogeneration equipment is compact through the use of container packages that incorporate auxil- In this paper, we introduced our one-stop solution iary equipment. By delivering containers with pre- for the power supplies of large-scale facilities. installed equipment to the site, we significantly re- In the field of power supplies, it is expected that duced construction costs and local installation man- efficient operation and energy-saving maintenance of hours and also decrease total costs. equipment will progress through the use of Internet As mentioned above, Fuji Electric received an or- of Things (IoT) technology. In the future, Fuji Electric der to supply power supply facilities as an EPC project plans to continue to listen to its customers, create new for which we carried out the engineering work as a added-value for its power supply systems and increase customer satisfaction.

One-Stop Solution for Power Supplies of Large-Scale Facilities 169 Technology of Digital Substation for Advanced Maintenance and Operation ISHIGAMI, Yuta * SUGITA, Kohei * NOGAWA, Michio *

ABSTRACT

The aged substation facilities in Japanese electric power industry has created the growing need to replace many of them. When replacing substation facilities, it is required to improve construction work efficiency, save costs, increase equipment reliability, and enhance maintenance and operation. To meet these needs, Fuji Electric developed IEDs and MUs in accordance with IEC 61850, an international standard that stipulates the configuration of digitalized substations. Connecting IEDs and MUs via Ethernet, we have been developing an IEC 61850 fully digitalized substation by using oversampling techniques and examining protection performance (3-cycle breaking).

1. Introduction 2. Trends in Substation Digitalization Technology The development of the Electricity System Reform has led to expansion in wide-area system operation Figure 1 shows a configuration example of the- in across regions. As a result, some challenges and prob- formation system in a digital substation. Up until lems have emerged, such as issues related to how to now, research on the practical application of station seamlessly connect power companies, maintain system buses has been advanced. In recent years, research on stability when a large number of distributed power sources are connected, cope with aging equipment, and

perform maintenance while dealing with labor short- Station level*1 Control console Substation server Power supply ages. It is against this backdrop that power utilities control are finding it necessary to improve efficiency in provid- station ing stable power supply and replacing facilities, while Ethernet*4 switch also reducing the cost of operations. Station bus In particular, the aged substation facilities in the Ethernet switch Ethernet switch Japanese electric power industry have created the growing need to replace many of them. When replac- Bay level*2 ing these facilities, it is necessary to improve construc- IED IED IED IED IED IED tion work efficiency, reduce costs, increase equipment Protective Protective Control Protective Protective Control reliability, and enhance maintenance and operation. relay relay unit relay relay unit To meet these needs, digital substations based on Ethernet switch Process Ethernet switch digital technology are expected to achieve when renew- bus ing or replacing substation facilities. Digital substa- CBC MU CBC MU CBC MU CBC MU tions are anticipated to reduce the hundreds of control DCC DCC DCC DCC cables installed in existing substations, streamline etc. etc. etc. etc. substation equipment and increase the efficiency of construction. In this paper, we will introduce digital substation Process level*3 technology for achieving advanced maintenance and operation. *1: Level related to the entire substation *2: Level related to single line and equipment *3: Level related to interface with main circuit equipment *4: Ethernet is a trademark or registered trademark of Fuji Xerox Co., Ltd. IED: Intelligent electronic device CBC: Circuit-breaker controller DCC: Disconnector controller MU: Merging unit

* Power Electronics Systems Energy Business Group, Fuji Fig.1 Configuration‌ example of digital substation information Electric Co., Ltd. system

170 the practical application of process buses has been actively conducted. Digital substations outside Japan tend to adopt common information models (CIM) and abstract communication service interfaces (ACSI) for monitoring and control information specified in the international standard IEC 61850. In Japan, digitalization of substations is also being researched in accordance with IEC 61850(1),(2). Hundreds of analog signal cables, such as for control signals, are installed in current substation systems. By using process buses that use optical fiber cables instead of analog signal cables, all information in substations can be digitalized. Process bus communications can be easily connected for equipment of Fig.2 External appearance of IED various manufacturers via the ACSI specified in IEC 61850. Input data from MUs to IEDs is digitalized, Analog signal cables currently connect lengthy dis- whereas analog input data has been used for voltage tances between outdoor process-level field equipment and current values and circuit breaker switching in- and indoor bay-level equipment. The use of process formation in a substation measured with conventional buses will reduce the number of analog signal cables, protective relays. Therefore, all MUs need to output decrease the size of on-site equipment through reduced time-synchronized digital data using a common time. wiring and achieve labor savings in construction. Fur- On the basis of the above descriptions, Fuji Elec- thermore, the use of process buses can also shorten tric has developed new IEDs and MUs based IEC construction periods and improve safety during con- 61850. Figure 2 shows the external appearance struction and maintenance. of the newly developed IED. Communications be- Moreover, sharing information via digitalization tween IEDs and MUs use the ACSI of IEC 61850. of information in the substations is expected to facili- Sampled values (SV) in ACSI are used to communi- Solutions Contributing to Stable and Optimal Power Supply Energy tate sophisticated monitoring and automatic control cate instantaneous voltage and current values and issue: functions, stabilizing substation system operation and generic object-oriented substation events (GOOSE) are preventing failures. In addition, by accumulating and used as a communication method for notifying status reusing various kinds of electricity measured data and changes to communicate circuit breaker switching. equipment information measured in multiple substa- Fuji Electric is currently working on the practi- tions over a long period of time, asset management is cal application of the time synchronization system de- expected to be advanced for substation equipment. scribed in Section 3.2 as a system that complies with the international standard IEC 61588. In addition, 3. Fuji Electric’s Substation Digitalization we are also working on the practical application of the Technology time asynchronization system described in Section 3.3.

Fuji Electric has been conducting research and 3.2 Model verification using a power system simulator development since 2011 for achieving practical appli- Fuji Electric has developed a power system simula- cation of digital substations, that is all information is tor that simulates a power system compliant with IEC digitalizes in substations. In the next section, we will 61850 and IEC 61588 as a preliminary step to building describe the development status of the equipment that a digital substation for use in the actual field. We built makes up digital substations. a digital substation model in this power system simulator. We verified the functions required by the digital 3.1 IEDs and MUs based IEC standard substation through in-house testing and then delivered The main equipment that makes up digital substa- it to Chubu Electric Power Co., Inc. We describe the tions includes intelligent electronic devices (IEDs) and power system simulator in the following sections. merging units (MUs). IEDs are protection calculating (1) System configuration of the power system simula- devices that detect various failures occurring inside tor and outside substations and output trip commands Figure 3 shows the system configuration of the to circuit breakers. MUs are input-output converters power system simulator. that convert voltage and current values and circuit The operation support system controls and moni- breaker switching information measured in a substa- tors the status of circuit breaker models in the digital tion into digital data to output to IEDs. The interna- substation model built in the power system simulator. tional standard IEC 61850 is generally used for com- The power system simulator connects multiple munications between IEDs and MUs. equipment models that simulate power distribution

Technology of Digital Substation for Advanced Maintenance and Operation 171 Station level Operation Network for operation support system support system SW FEP 1 Gbps Bay level GMC SW 1 Gbps 1 Gbps Network for models (station bus) SW SW SW 100 Mbps IED (B) × 3

Digital substation Process level model SW SW 1 Gbps MU × 34 Circuit breaker models, etc. Network for FEP : Front end processor IED (A) × 191 models SW : Network switch (process bus) GMC : Grandmaster clock IED : Intelligent electronic device Circuit breaker switching information MU : Merging unit VCT measurement value VT : Instrument transformer CT : Current transformer VT VT CT VT CT VCT : Voltage current transformer

Fig.3 System configuration of the power system simulator equipment on the basis of the system configuration in FEP and displayed in real time as a graph on the client order to configure an equivalent abbreviated system PC of the operation support network. (abbreviated model). These abbreviated models consist (3) Types of IED and MU of analog models and hybrid models. In analog models, Table 1 describes the types of IEDs and MUs. A power distribution equipment, such as transformers total of 228 IEDs and MUs are connected to the net- and transmission lines, is represented by abbrevi- work in the digital substation model (model network). ated models using R, L, and C elements. On the other A total of 191 measurement control IEDs (A) are con- hand, hybrid models digitally calculate the character- nected to the station bus. A total of 3 protection con- istics of synchronous generators, photovoltaic power trol calculating IEDs (B) are connecting to both the generation systems, and utility customer loads and station bus and process bus. In addition, a total of 34 output analog current values according to the calcula- instantaneous measurement MUs are connected to the tion results. process bus. Each IED and MU is interconnected us- In order to build a digital substation in the power ing an Ethernet switch compliant with IEC 61850 and system simulator, information and communication IEC 61588. equipment consist of the following three elements: (4) Time synchronization and sampling synchroniza- (a) MUs that sample instantaneous values of sys- tion tem voltages and currents Accurately analyzing and evaluating the digital (b) Measurement control IEDs that control circuit substation simulation results in the power system breakers simulator need sampling synchronization; that is, the (c) Protection control calculating IEDs that calcu- data measured by IEDs (A) and IEDs (B) distributed late protection control throughout the abbreviated system needs to be inte- (2) Overview of communications grated without delay according to the sampling time. 1 This system uses the Ethernet* communication In addition, IEDS (B) for protection control calculation network. The operation support system is connected always perform protection control calculation using the to the models of circuit breakers and other equipment instantaneous values of voltage and current sampled in the digital substation model via the operation sup- by multiple MUs that are time synchronized with high port system network. Control commands to the equipment models are converted according to the IEC 61850 Table 1 Types of IED and MU protocol by a front end processor (FEP), which serve as Type Name Qty. the high level server in charge of the substation, and IED (A): For measurement 191 then sent to the IEDs in the equipment model. In con- control IED trast to this, real-time monitoring data transmitted by IED (B): For protection control 3 the IED in each equipment model is aggregated by the calculation MU MU 34 *1: ‌Ethernet is a trademark or registered trademark of Fuji Total 228 Xerox Co., Ltd.

172 FUJI ELECTRIC REVIEW vol.65 no.3 2019 accuracy. Therefore, they always require highly accu- MUs send the system information to the process bus rate time-synchronized measurement data, in contrast using SV and GOOSE, which are IEC 61850 ACSIs. to the method of acquiring measurement data only in The IEDs (B) perform protection control calcu- a certain time interval by a preset trigger like typical lation with the data received from the MUs via the general power waveform recorders. As a result, all process bus using SV and GOOSE. The breaking and IEDs and MUs in the abbreviated system must always closing commands generated by this calculation are perform measurement and control in synchronization transmitted to the IEDs (A) via the station bus. For with a single reference time. The grandmaster clock the protection control calculations of the IEDs (B), us- (GMC) is used as the reference time for the entire sys- ers can create their desired control logic. tem. The IEDs (A) receive the breaking and closing com- In the network for the operation support system, mands to the circuit breakers from the IEDs (B) con- time synchronization was performed using the net- nected to the station bus using GOOSE to open or close work time protocol (NTP). In the network for models, the circuit breakers. time synchronization is performed using the precision (6) Programmable functions with Simlink time protocol (PTP) specified in the IEC 61588 to sup- The IEDs (B) come with a programmable functions port highly accurate time synchronization. As a result, that allow users, rather than IED manufacturers, to the IEDs and MUs in the network for models achieved implement software applications. Users can program time synchronization accuracy within ±1 μs relative to their desired control logic utilizing instantaneous val- the GMC reference time. ues as input by using Simulink*2, a commercially By using the time synchronization technology de- available application software, installed in the op- scribed above, all IEDs in the abbreviated system ac- eration support system of the power system simulator. quired data with a time synchronization accuracy of Desired control logic can be developed by combining 20 μs or less. This is a sufficient time synchronization control blocks (see Table 2) prepared in advance on the accuracy for power system simulators. Simulink screen. (5) Custom control relay model This function can be used for users to verify the ef- A custom control relay model (Ry model) for simu- fectiveness of the introduction of large-scale systems lating the protective relay system in the digital substa- through developing new protective relay control logic tion is created with the combination of IEDs (B) and and verifying the control logic for new stabilization Solutions Contributing to Stable and Optimal Power Supply Energy MUs as shown in Fig. 4. systems, in addition to analyzing and evaluating sys- issue: The MUs in the Ry model measure the voltage tem operation results and system behavior. and current of the abbreviated system from the input terminals of the voltage transformers (VTs) and cur- 3.3 Efforts to put digital substations into practical use rent transformers (CTs) at a sampling frequency of On the basis of the basic technology and achieve- 5,760 Hz. Furthermore, the MUs also acquire the circuit breaker switching information output from the *2: ‌Simulink is a trademark or registered trademark of The contacts of the circuit breaker models in real time. The MathWorks, Inc.

100-Mbps L2SW (IEC 61850/IEC 61588 compliant) Station bus

GOOSE Circuit breaker Operation support system switching command DSP SV CPU Programming IED control logic via Simulink* board board board Protection control calculation Process bus

IED (B) No.1 Receive communication to IED (B) No.2 select 5 MUs IED (B) No.3 Circuit breaker model Select 5 IEDs (A) 1-Gbps L2SW (IEC 61850/IEC 61588 compliant) SV GOOSE Voltage / current Circuit breaker IED (A) information MU IED : Intelligent electronic device MU SV : Sampled values 5,760 Hz MU: 34 units DSP : Digital signal processor VT CT sampling GOOSE : Generic object- oriented substation events VT MU : Merging unit CT VT : Instrument transformer CT : Current transformer Voltage, current measurement / breaker switching information *Simulink is a trademark or registered trademark of The MathWorks, Inc.

Fig.4 System configuration of the Ry model

Technology of Digital Substation for Advanced Maintenance and Operation 173 Table 2 Blocks of protective relay elements ciency. Facili- Furthermore, to digitalize substation monitoring Protection method Protective relay element block ties systems and protection and control equipment, it is PCM* current dif- necessary to consider the constraints of sampling time ferential relay 87P, 27S/G, 51G (direct grounding) synchronization method of widely-adopted PCM current differential relays and the fault clearing time of PCM current differential relay super high-voltage substations. 87S/G, 64, 27B (resistance ground- (2) Adoption of oversampling method ing) An oversampling method uses sufficiently higher Line selection 50S/SA/G2/G3, 67GS, 64, 27 sampling frequencies for MUs and other devices than Power Overcurrent 51, 51G, 64 lines 5,760 Hz (in 60 Hz system) used in the existing substa- Short-circuit, ground fault dis- tion system. tance 44S/G, 27Gφ, 51G Operating these devices asynchronously sampling (direct grounding) at the sampling frequency of existing substation sys- Short-circuit, tems can cause a time deviation. As a result, there ground fault distance 44S, 51φ, 67G/GA, 64 could be performance degradation in detecting the fail- (resistance ground- ure of protective relays, which are premised on time ing) synchronization. The timing deviation of sampling due 87, 51, 87G, 67G, 51G, 64 Trans- For - -Δ to the asynchronous time decreases as the sampling form- For -Δ 87, 51, 87G, 67G, 51G, 64 frequency increases. Therefore, time synchronization ers For - 87, 51, 87G, 51G, 64 can be eliminated when the sampling frequency is in- *PCM: Pulse code modulation creased so as to coincide with the allowable range of the failure detection accuracy of the protective relay. ments of the IEDs and MUs developed in the power On the other hand, time differences that cannot be system simulator, Fuji Electric has been working with decreased by oversampling will vary due to the delay Chubu Electric Power Co., Inc. in the research and characteristics of each analog filter (AF) in the MUs demonstration of new methods using technologies that and other devices. In order to suppress the impact of do not require time synchronization. this variation in the processes performed by the device (1) Challenges facing practical use of digital substa- functions as shown in Fig. 5, the delay in processing tions until the IED receives data, processing(1) to (2), is kept Communication networks for typical digital sub- within a certain range, allowing the sampling values stations are built from communication devices, such from multiple MUs to be treated as same-time infor- as layer 2 communication switches (L2SW), and GMC mation. for providing accurate time information to synchronize (3) Ensuring protection performance (3-cycle break- the time of those devices. However, if the GMC stops, ing) there is a risk that differential relays, which oper- In addition to accuracy and reliability, protective ate on the assumption of sampling synchronization, relays need to have quick response to fault clearing. will operate unnecessarily. Moreover, since a certain Even in digitalized substations, they are required to amount of knowledge is required when performing break within 3 cycles in the same manner as conven- L2SW connection and setting work, there are chal- tional protection systems. In other words, they need lenges regarding how to prevent human error during to clear faults within 50 ms for 60 Hz systems. Figure operation maintenance and improving working effi- 5 shows the process sharing of each protection system

(2) Transmission (3) Relay calculation (1) Input processing processing (upstream) processing

MU IED Trans- PCT AF A/D mission processing Reception E/O SP O/E processing DF DI Trans- contact mission input processing PCT : Input converter AF : Analog filter DO Trans- Ry A/D : Analog digital converter contact Reception DI : Digital input processing O/E SP E/O mission Calcu- output processing lation E/O : Electric/optical media converter SP : Optical splitter O/E : Optical/electric media converter DF : Digital filter Ry : Relay (5) Output processing (4) Transmission processing (downstream) DO : Digital output

Fig.5 Process sharing of each function

174 FUJI ELECTRIC REVIEW vol.65 no.3 2019 function in a digital substation to satisfy the requirement and characteristic uniformization) ment for breaking. (c) The suppression of delay and variation in trans- In order to break within 3 cycles, it is necessary to mission by employing optical splitters (SPs), contract the variation of the delay time and process- which have responsiveness and higher reliabil- ing time required for the processes of each function, ity than L2SW. including (1) input processing, (2) transmission pro- Currently, we are prototyping a protective relay cessing (upstream), (3) relay calculation processing, (4) system based on these measures and are verifying the transmission processing (downstream) and (5) output performance. We are also performing the development processing, as shown in Fig. 5. To achieve this, the fol- for achieving a digital substation capable of applying lowing measures were implemented: oversampling methods to power system facilities. Fig- (a) Relay calculation and digital filter (DF) optimi- ure 6 shows a configuration example of a digital- sub zation station designed for practical use. (b) Analog filter (AF) simplification (speed enhance- 4. Postscript

Digital substation Higher level computer, etc. In this paper, we introduced digital substation

Indoor control room technology for achieving advanced maintenance and operation. Station bus L2SW L2SW We believe that these initiatives and their results

IED for protection will contribute to the practical application of digital control and monitoring IED IED IED IED substations, thereby creating new value and profits. Process bus Devices such as IEDs and MUs and communication technologies specified in IEC 61850, which are used in digital substations, are being increasingly Optical Optical Optical Optical Optical Optical splitter splitter splitter splitter splitter splitter applied to various fields: distributed power sources, smart grids, storage batteries, wind turbine genera- MU MU MU MU MU MU tion, hydroelectric power generation, thermal power generation, and EVs. In the future, we plan to work on Solutions Contributing to Stable and Optimal Power Supply Energy Instru- Circuit Instru- the product development of these fields. ment breaker, ment Circuit issue: trans- discon- Sensor Sensor trans- breaker, former nector former ... References Switchgear-1 Transformer-1 to n to n Bus-1 to n (1) “IEC 61850-5 Edition 2.0 Communication require- Control cable ments for functions and device models”. 2013. Outdoor main unit (2) IEC 61850-9-2 Edition 2.0 Specific communication service mapping (SCSM) – Sampled values over ISO/IEC Fig.6 Configuration‌ example of digital substation for practical 8802-3”. 2011. use

Technology of Digital Substation for Advanced Maintenance and Operation 175 Countermeasures Against the Introduction of Large Amounts of Renewable Energy in the Distribution Field and Support for BCP MATSUEDA, Tsurugi * MOCHIZUKI, Masaki * JINTSUGAWA, Toru⁑

ABSTRACT

Since the enactment of the Feed-in Tariff Scheme for Renewable Energy (FIT), large amounts of renewable energy such as photovoltaic power generation have been introduced into distribution systems, thereby complicating the voltage management of distribution systems. To deal with this difficult situation, Fuji Electric has developed voltage regulators and centralized voltage control systems for centrally controlling the regulators. We have also developed a wide-area backup distribution automation system that meets the requirements of business continuity plans (BCPs), which have been strongly required since the Great East Japan Earthquake, by using virtualization technologies and our proprietary configuration control middleware. Furthermore, participating in a New Energy and Industrial Technol- ogy Development Organization (NEDO) project, we have built a comprehensive distribution management system using these technologies and performed demonstration tests for it in India.

1. Introduction ratio control transformers (LRTs) at distribution substations and automatic step voltage regulators (SVRs) Since the enforcement of the Feed-in Tariff Scheme located on the lines. However, this type of equipment for Renewable Energy (FIT) in 2009, large amounts has slow control response and can only perform dis- of renewable energy such as photovoltaic power gen- crete voltage adjustment, and therefore it can hardly eration have been introduced into distribution systems, maintain the voltage in the adequate range when the thereby complicating the voltage management of dis- output of renewable energy changes suddenly. To tribution systems. Therefore, Fuji Electric has devel- solve this problem, the use of flexible AC transmis- oped a static var compensator (SVC) as a voltage regu- sion systems (FACTSs) is increasing to adjust voltage lator for distribution systems. We have also developed quickly and continuously. a centralized voltage control system that controls volt- Fuji Electric and Tohoku Electric Power Co., Inc. age regulators including SVC from a central system. have jointly researched and developed a new separately- Meanwhile, since the Great East Japan Earth- excited SVC for distribution systems using a variable quake, preparing business continuity plans (BCPs) and inductor with magnetic flux control technology(1). taking precautions are required for distribution auto- Figure 1 shows the basic principles of the new mation systems to continuously operate even during disasters. To meet these needs, we have developed virtualization technology, virtual network computing (VNC) AC flux and proprietary configuration control middleware. AC circuit In addition, we built a comprehensive distribution DC flux management system in Panipat, Haryana State in In- Control winding dia by participating in the smart grid demonstration Control project managed by the New Energy and Industrial circuit AC main Technology Development Organization (NEDO) and winding Uttar Haryana Bijli Vitran Nigam Limited. We have Control current (DC) then verified the usefulness of the system in mitigating Iron core power quality issues faced by Indian power distribution companies. DC flux effect on magnetic circuit Permeability change 2. SVC for Distribution System Effective inductance change In conventional distribution systems, voltage ad- Inductance change (Variable inductor) justment is performed mainly by tap change of load AC power control by adjusting DC flux

* Power Electronics Systems Energy Business Group, Fuji Electric Co., Ltd. Fig.1 ‌Basic principles of the separately-excited SVC for distribution systems ⁑ Corporate R&D Headquarters, Fuji Electric Co., Ltd.

176 separately-excited SVC for distribution systems. It can control current flowing through the reactor using 3. Centralized Voltage Control System direct current (DC), eliminating the use of a harmonic filter to achieve more simple configuration - thanbe Conventional voltage regulators use measurement fore. The AC winding and control winding are wound information at connection points to determine the around the magnetic core. When DC flows through the amount of control (local control). However, the in- control winding, magnetic saturation occurs and ef- troduction of large amounts of renewable energy has fective permeability decreases. With this mechanism, complicated the voltage management of distribution SVC controls the magnetic flux density and changes systems. As a result, existing voltage control methods the effective magnetic permeability to control the in- cannot achieve coordination between those regula- ductance, adjusting the reactive power flowing into the tors and this can make it difficult to control voltage system. Its main circuit can only consist of iron cores accurately. To maintain the voltage of the entire dis- and windings, allowing it to ensure reliability due to tribution system within a proper range, employing a the high resistance to surge current. Moreover, since centralized voltage control system has been considered. the control current that regulates the reactive power It collects measurement data from sensor equipped is DC, the control circuit and software algorithm are switches and voltage regulators in the main system simplified. and controls each voltage regulator in real time. Figure 2 shows the external appearance of the new Fuji Electric developed the centralized voltage separately-excited SVC for distribution systems and control system shown in Figure 3 by participating the Table 1 describes its specifications. In order to verify NEDO’s “Experimental Project of Advanced Power the operation of voltage adjustment by the SVC, we Grid with Distributed Energy Sources.” The central- have been conducting field tests on actual distribution ized voltage control system is shown as a standalone lines operated by Tohoku Electric Power Co., Inc. with system in Fig. 3, but we are expecting that it will be their cooperation. implemented as a component of distribution automation systems in the future. The centralized voltage control system has the following features: (a) Collects measurement data at regular intervals from the voltage regulators and sensor equipped Solutions Contributing to Stable and Optimal Power Supply Energy switches installed at some points on the power issue: distribution system. (b) Ascertains the status of the entire system and calculates the optimum command value for each voltage regulator. (c) Distributes command values to each voltage

(1) Measurement data SVC collection

(2) Optimal Fig.2 ‌External appearance of the separately-excited SVC for command value distribution systems Sensor SVR Sensor calcu- equipped equipped lation switch switch Load Load Large Table 1 ‌Specifications of the separately-excited SVC for distribu- scale PV PV tion systems LRT PV Item Specification (3) Command value distribution Rated capacity 300 kVA V, I, θ Variable capacity 0 to 300 kvar (delayed) SSSC Rated voltage 6,600 V Sensor Sensor equipped equipped Frequency 50/60 Hz switch switch Cooling system Natural cooling Load Load Load Mass 4,000 kg or less PV PV PV

Dimensions W2,500 × D1,500 × H2,000 (mm) PV : Photovoltaic cell SVC : Static var compensator Variable inductor Main circuit LRT : Load ratio control transformer (Harmonic filterless) SVR : Step voltage regulator SSSC : Static synchronous series compensator

Fig.3 ‌Conceptual diagram of a centralized voltage control system

Countermeasures Against the Introduction of Large Amounts of Renewable Energy in the Distribution Field and Support for BCP 177 regulator in real time and controls them. In addition to conventional voltage regulators such Max. voltage Min. voltage as LRTs and SVRs, this newly developed centralized 6,900 voltage control system can control next-generation 6,800 Voltage control voltage regulators, including SVCs and static synchro- upper limit nous series compensators (SSSCs). By delivering tar- 6,700 get voltages as command values to SVCs and SSSCs, 6,600 it can take advantage of the high-speed voltage control Voltage (V) 6,500 inside the equipment and achieve high-performance to 6,400 Voltage control lower limit maintain voltage. 6,300 In addition, to calculate the optimal command 0:00 6:00 12:00 18:00 0:00 value, we took following 2 points into consideration, Time as well as optimizing the voltage of the entire distribu- (a) Local control tion system. The first is to reduce the number of tap 6,900 switchings for LRTs and SVRs. This can extend the 6,800 life expectancy of LRTs and SVRs. The second is the Voltage control upper limit output sharing optimization of multiple SVCs. This 6,700 made it possible to maintain SVC compensation per- 6,600

formance against sudden voltage changes and reduce Voltage (V) 6,500 power loss due to reactive current. 6,400 Voltage control lower limit In the configuration shown in Fig. 4, we conducted 6,300 real-time comprehensive testing for the centralized 0:00 6:00 12:00 18:00 0:00 voltage control system. The power system and volt- Time age regulator were simulated with a digital simulator (b) Centralized voltage control and linked to the centralized voltage control program installed on a general-purpose PC via an intelligent Fig.5 Result of real-time comprehensive operation test electronic devices (IEDs). These IEDs and PC come equipped with communication systems that comply was maintained within the proper range during cen- with the electric power communication standard IEC tralized voltage control, thereby showing advantages. 61850 because the interoperability of multiple vendors Furthermore, we verified the effect of using the is needed to achieve advanced distribution network centralized voltage control system under various condi- management. tions by offline simulation. We found that this system As shown in Fig. 5, we built a simulated system is particularly effective when multiple voltage regula- that consists of two SVCs and two SSSCs to perform tors are installed on lengthy distribution lines. In par- 24-hour comprehensive operation tests with a mea- ticular, in distribution systems consisting of multiple surement and control interval of one minute. These voltage regulators, including next-generation devices, tests showed that this system worked without prob- employing the centralized voltage control system can lems. Fig. 5 also shows that the voltage deviated from be expected to increase the likelihood of introducing the appropriate range during local control, whereas it photovoltaic power generation by 10% to 20%.

4. BCP Compliant Operation During Widespread Centralized voltage control program installed on Disaster general-purpose PC As mentioned in Chapter 1, in recent years from Command value the point of view of BCP, distribution automation systems are required to continue the operation even if a LAN Measurement value IED IED IED IED large-scale disaster inflicts damage on server installation or operational sites. To meet this need, Fuji Simulated SVC Electric has developed a wide-area backup distribution system SSSC automation system that supports BCPs. SSSC SVC 4.1 System configuration Real-time digital simulator Figure 6 shows the system configuration of our IED : Intelligent electronic device wide-area backup distribution automation system. SVC : Static var compensator SSSC : Static synchronous series compensator This system is duplicated with the servers deployed at two sales offices several tens to hundreds of kilome- Fig.4 Configuration‌ diagram of a real-time comprehensive ters apart to continue the operations even if one of the operation test sales offices is damaged. Each sales office uses a pri-

178 FUJI ELECTRIC REVIEW vol.65 no.3 2019 Distribution automation Distribution Distribution Distribution automation console automation automation console server A Tens to hundreds server B of km

Server A Power Network Center Server B Power Network Center

Tens of km Power IP network

Distribution Distribution Distribution automation automation automation console console console

Client Power Network Client Power Network Client Power Network Center 1 Center 2 Center n

Fig.6 Wide-area backup distribution automation system. vate cloud system and has multiple console PCs. The mation system. console PCs are fanless and diskless thin clients*1, and The console PCs connect to each client virtualiza- each device and network is duplicated to continue op- tion in server A in active mode via VNC and display erations in the event of a failure in a single equipment the screens. VNC is remote desktop software for dis- or a single communication line. playing the screens of the server’s client virtualization In the wide-area backup distribution automation on a remote console PC via a network. By using virtu- system, “operation virtualization” for implementing alization technology and VNC, all information includ- operation applications and “client virtualization” for ing application software is stored in the server. Each displaying the screen are built within each server. The console PC is only used for displaying and operating Solutions Contributing to Stable and Optimal Power Supply Energy number of installed client virtualizations is same as screens located in the server. Since no information is issue: that of consoles. Figure 7 shows the virtualization en- actually stored in the PC, security can be ensured and vironment of our wide-area backup distribution auto- maintenance can be simplified.

4.2 Disaster recovery operation Distribution automation Distribution automation It is necessary to minimize suspensions of opera- server A server B tion in the event that a server (for example, server A) becomes inoperable due to server maintenance or damage to the sales office where the server is installed. Operation virtualization Operation virtualization Fuji Electric has developed proprietary configuration Client Power Client Power Client Power Client Power Network Center 1 Network Center 2 Network Center 1 Network Center 2 control middleware that switches the operating mode Work Work Work Work Work Work Work Work of the server within 1 second after detecting an abnor- screen screen screen screen screen screen screen screen mality. Client Client Client Client Virtualization Virtualization virtualization virtualization Furthermore, the client virtualization for both 1 1 1 1 server A and B is continuously in a state capable of

Work Work Work Work Work Work Work Work displaying the screen. For example, if server A stops, screen screen screen screen screen screen screen screen the console PC will automatically switch the connec- Client Client Client Client tion to the client virtualization of server B. Figure 8 virtualization virtualization virtualization virtualization n n n n shows the behavior of the system when server A stops due to a disaster or other issues. In addition, if a client sales office is damaged as Distribution Distribution automation automation shown in Fig. 9, the other client sales office can access console console Client Power Network Client Power Network the client virtualization of the damaged sales office to Center 1 Center 2 monitor and control the damaged sales office.

Fig.7 Virtual‌ environment of the distribution automation system supporting BCP

*1:‌ A thin client is a mechanism that runs processes on the server side with very little information on user terminals.

Countermeasures Against the Introduction of Large Amounts of Renewable Energy in the Distribution Field and Support for BCP 179 tion loss. Distribution automation server A Distribution automation server B (Active ⇒ stoppage) (Standby ⇒ Active) The results of basic surveys and the pre- Mode transition demonstration surveys showed that the need for solving these problems was particularly high in the Panipat area of UHBVN. Therefore, we participated in a NEDO Operation virtualization Operation virtualization Client Power Client Power Client Power Client Power demonstration project during October 2015 to March Network Center 1 Network Center 2 Network Center 1 Network Center 2 2019 to built a comprehensive distribution manage- Work Work Work Work Work Work Work Work screen screen screen screen screen screen screen screen ment system using smart grid-related technologies in

Client Client Client Client Panipat. This enabled us to demonstrate and evaluate virtualization virtualization virtualization virtualization 1 1 1 1 the effectiveness of solving these problems.

Work Work Work Work Work Work Work Work 5.1 Demonstration system configuration screen screen screen screen screen screen screen screen As shown in Fig. 10, in this demonstration, we Client Client Client Client virtualization virtualization virtualization virtualization installed distribution equipment and smart meter- n n n n related equipment for the distribution system that Line Line consists of 3 substations and 4 feeders in Panipat. switching switching Moreover, we built a comprehensive distribution man- Distribution Distribution automation automation agement system based on supervisory control and data console console Client Power Network Client Power Network acquisition (SCADA) and demonstrated its effective- Center 1 Center 2 ness of solving the problems. Each component of the system can be broadly categorized as follows: Fig.8 Operation at time of server A stoppage (1) Higher level system (SCADA, etc.) We built a SCADA system that monitors and controls the distribution equipment, an outage manage- Distribution automation Distribution automation server A server B ment system (OMS) that manages power outages using information from the SCADA, and a meter data management system (MDMS) that links with the existing

Operation virtualization Operation virtualization fee collection system of UHBVN and manages smart Client Power Client Power Client Power Client Power meter data on a per customer basis. We installed Network Center 1 Network Center 2 Network Center 1 Network Center 2 these higher level system servers in the UHBVN data Work Work Work Work Work Work Work Work screen screen screen screen screen screen screen screen center and four consoles in the newly established op- Client Client Client Client eration center. Virtualization Virtualization Virtualization Virtualization 1 1 1 1 (2) Distribution equipment We installed 4 vacuum circuit breakers (VCB) at Work Work Work Work Work Work Work Work 3 substations, and 22 load breaking switches (LBS) at screen screen screen screen screen screen screen screen 4 feeders. In addition, each VCB and LBS are respec- Client Client Client Client virtualization virtualization virtualization virtualization tively equipped with a remote terminal unit (RTU) and n n n n feeder terminal unit (FTU) communication equipment Operable as Client Power Network Center 1 so that SCADA can monitor and control each VCB and LBS. Distribution Distribution automation automation console console (3) Smart meter-related equipment Client Power Network Client Power Network We installed 11,000 single-phase and three-phase Center 1 Center 2 smart meters and 67 data concentrator units (DCU) that control meters and collect data from them. The Fig.9 Substitutive operation at time of client office stoppage meter data collected by the DCUs is transmitted to the MDMS via the head end system (HES).

5. Comprehensive Distribution Management 5.2 Verification of effectiveness of demonstration system System Demonstration (NEDO Demonstration We used the comprehensive distribution manage- in India) ment system built in Panipat to verify the effectiveness of solving the 3 problems of UHBVN, which included In India, economic growth has increased the de- shortening accidental power outage times, reducing mand for electricity, and this has resulted in chronic peak load and distribution loss. shortages of electricity due to delays in infrastructure (1) Verification of effectiveness of shortening outage development. Therefore, many power distribution times companies in India have problems related to power In the Panipat demonstration project, we verified quality and need to implement measures to shorten the effect of improving the outage time and frequency accidental outage times, reduce peak load and distribu- by comparing the system average interruption dura-

180 FUJI ELECTRIC REVIEW vol.65 no.3 2019 Panipat Operations Center Fuji Electric Equipment manufacturer in India Accounting system Uttar Haryana Bijli Vitran Nigam Limited Servers MDMS OMS SCADA HES Substation

Wireless communications / GPRS (2G / 3G)

LBS LBS VCB

SM SM SM SM SM SM VCB : Vacuum circuit-breaker LBS : Load break switch SM : Smart meter Smart meter GPRS : General packet radio service

Fig.10 Conceptual diagram of the demonstration system configuration tion indexes (SAIDI) and system average interruption tion feeder with that of the smart meters under the frequency indexes (SAIFI) before and after introducing DT to measure and analyze the distribution loss in the the SCADA system. By comparing 2017 with 2018, the feeder. As a result, we found that the average power years before and after SCADA system introduction, we distribution loss rate on a daily basis in the demon- confirmed that SAIDI has improved by 66% and SAIFI stration area was high, approximately 38.0%. Fur- by 26%. Moreover, with regard to accidental outages thermore, we analyzed the change in the time of the collected during the demonstration period, we con- distribution loss on a daily basis and found that histor- firmed that the average outage time in the target dem- ical changes were almost the same as the change in the Solutions Contributing to Stable and Optimal Power Supply Energy onstration feeder could be reduced by approximately time of power usage by utility customers. On the basis issue: 62% by using the SCADA system to quickly identify of this result, we believe that the main cause of distri- accident points and interchange electricity from the bution loss is due to a large percentage human-induced other feeders. These results showed the improvement loss, such as power theft. We believe that the locations in the power supply reliability of the target demon- of power theft can be ascertained. After communica- stration feeder through the use of the SCADA system. tion infrastructure is established in India, we plan to However, this improvement also reflects some of the compare the DTs with smart meters for the amount recent enhancements in power quality itself in India. of electric power on a per-section basis, identify large The system was transferred from NEDO to UHBVN sections of distribution loss, and then conduct an inten- through the Ministry of Power in India after the com- sive field survey of the relevant sections. pletion of the demonstration project. In the future, we plan to continue carrying out high-precision compara- 6. Postscript tive analysis. (2) Verification of peak load reduction effect By providing the distribution automation system Using the data of electric power consumption col- and SVCs described in this paper, Fuji Electric has lected from smart meters, we verified the effectiveness contributed to solve the problems of instability in dis- of peak load reduction through the demonstration sys- tribution systems caused by the introduction of large tem. First, we grouped utility customers by power con- amounts of renewable energy and has also contributed sumption. Then, we performed a simulated demand to the continuation of system operations at the time response for each group. In particular, we used the of disasters. We will continue to develop systems and power limiting function of the smart meters to limit equipment that can support more complicated distribu- the amount of power used for each group in turn and tion systems operation with peace of mind. then verified the demand reduction effect by - simula A portion of these achievements was obtained in tion. As a result, we confirmed that the peak of overall the “Demonstration Project of Advanced Power Grid demand can be reduced by using the power limiting with Distributed Energy Sources” coordinated by the function of smart meters. New Energy and Industrial Technology Development (3) Verification of power distribution loss reduction Organization (NEDO). We would like to conclude by effect expressing our appreciation to all those involved in We compared the total amount of electric power of this project. the distribution transformer (DT) in the demonstra-

Countermeasures Against the Introduction of Large Amounts of Renewable Energy in the Distribution Field and Support for BCP 181 References (1) Kojima, T. et al. Distribution Static Var Compensators and Static Synchronous Compensators for Suppressing Voltage Fluctuation. FUJI ELECTRIC REVIEW. 2017, vol.63, no.1, p.36-40.

182 FUJI ELECTRIC REVIEW vol.65 no.3 2019

cl pwr rdcr ad upir, e r provid are we suppliers, and producers power scale medium- and small- for Therefore, large. to small from varies suppliers and producers power of scale business The system. management demand-supply power the of 2. tem andVPPsolution. sys management demand-supply power our introduce will we paper, this In (VPPs). plants power virtual project for demonstration a in participated continuously has Electric Fuji systems. power stabilizing of means a as (DERs) resources energy utilizes distributed demand-side that scheme a building been has country the power trade and through the Japan Electric Power Exchange. Operators, Cross-regional Transmission for of Organization Coordination the to submis plans values, of actual sion and forecasts imbal between in ances increase suppress to functions forecasting demand operators, system demand transmission of from acquisition results manage includes functions demand-supply Its high-precision of ment. achieve operation efficient that and functions various system this has Furthermore, bal planned-value rules. new operational the ancing of capable management are electric demand-supply systems Our retail 2016. of April deregulation in ity full sup the and since producers pliers power to systems management 1. *

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issue: Energy Solutions Contributing to Stable and Optimal Power Supply External agency interface FIT power Next-day plan Current day generation plan (Actual day-before monitoring Demand Demand forecasting (Actual 2-days-before demand-supply) (Actual current day Transmission results demand-supply) demand-supply) system operator Demand result Demand receiving forecasting FIT (1) Demand Imbalance (TSO) Status 1 forecasting monitoring Weather Imbalance plan creation information Weather receiving monitoring Bid information Japan Electric Demand company Weather Power Power generation forecasting plan creation forecast Market transaction Exchange correction (JEPX) Weather Market transaction Contract FIT (1) results result Status 1 Power plan Demand-supply generation plan creation Supply and demand plan submission plan revision Organization for Plan Power Supply and BG management Cross-regional generation plan demand plan Plan management report Demand-supply Coordination of Spot market plan revision Optimization Transmission FIT (1) transaction Operators Status 2 Plan report creation (OCCTO) plan Intraday Power generation Demand and receiving market Utility and sales plan procurement plan Demand-supply customer data plan revision Power Demand management data Demand-supply generation plan revision results, etc. FIT (1) Master Result Plan Cost Power Plan report Other systems ○Utility ○Demand ○Demand ○Procure- generation creation and customer result ○Procure- ment cost Revision plan ○Power ○Power ment and ○Bid result plan creation submission report creation station generation sale and submission result

(a) Business process flows of supply and demand management (b) Power demand-supply management system function configuration diagram

Fig.1 Business process flows and power demand-supply management system function configuration diagram

Table 2 List of demand-supply management system functions ances are expected to increase. ○: Function used for each process Table 2 shows the main functions of the system. Response to The system comes with a planning management func- process flow Function Description tion that enables the creation of daily supply and de- Next Cur- FIT rent mand plans in the future to balance the demand and day day procurement amount of electricity. Furthermore, op- Acquires actual power demand Demand values every 30 minutes from erators can see past plans and cost data, as well as re- result — a transmission system operator ◯ ◯ receiving sults, stored in the system. (TSO) (2) Data linkage functions with external agencies to Weather Acquires weather forecasts / ac- information tual results data from weather — ◯ ◯ provide a one-stop service receiving information companies Daily supply and demand management operation Forecasts demand for power Demand data must be shared with 3 external agencies, includ- consumption every 30 minutes — forecasting ◯ ◯ for each forecast group ing the Organization for Cross-regional Coordination Calculates the imbalance be- of Transmission Operators (OCCTO), transmission Imbalance tween actual demand values — monitoring — ◯ system operators (TSOs), and the Japan Electric Power and forecast values Exchange (JEPX). We have developed the application Performs bidding and contract Market interface for data linkage functions with external agen- result receiving for day-before — transactions ◯ ◯ and current day markets cies described in Table 3 and implemented it in the Power Creates power generation plans power demand-supply management system as stan- generation for power plants on a 30-minute ◯ ◯ ◯ dard functionality. These functions in combination planning basis with the business functions described in Table 2 enable Allocate own power and pro- Supply and cured power from other compa- one-stop service operation for supply and demand man- demand — nies to fill the demand forecast ◯ ◯ plan agement. results (plans) (3) Support for balancing groups Creates a plan report (demand Planning and procurement plan, power The system supports balancing group (BG) op- report generation and sales plan) ◯ ◯ ◯ eration*2 in which the delegate of contractors coordi- creation based on the results of the sup- nates multiple individual companies (PPSs) to conduct ply and demand plan planned-value balancing operation. As shown in Manages demand plans, power Fig. Plan generation plans, and supply 2, the master structure has 3 layers, including de- management and demand plans daily and ev- ◯ ◯ ◯ ery 30 minutes 2: Balancing Group (BG): Consolidate multiple individual Manages demand plans, power * BG generation plans, and supply companies (PPSs) including one’s own company, and ◯ ◯ ◯ management and demand plans for each in- have delegate of contractors (one’s own PPS) perform dividual company supply and demand management.

184 FUJI ELECTRIC REVIEW vol.65 no.3 2019 Table 3 ‌Methods for sharing data and communicating with external agencies Same operation day Voltage class Destination Data Communication method Extra-high voltage (Extra high) Area forecasting group (1) EDI common standard for Planning report recipients of power genera- OCCTO Same day of the week data tion planning Extra-high voltage (OCCTO) forecasting group (2) EDI common standards between retail electricity utili- Similar day weather Actual power ties and general electricity Voltage class TSO High-voltage forecasting group (1) (High voltage) demand values transmission and distribution utilities High-voltage forecasting group (2) (OCCTO) JIT* Bidding and con- Market participant API JEPX Low-voltage forecasting group (1) Voltage class tract information (JEPX) (A prefecture) (Low voltage) Low-voltage forecasting group (2) (B prefecture)

BG (balancing group) implementation Build-up plan class specific master structure creation illustration Aggregate by Aggregate by *JIT: Just-In-Time voltage class area of TSO 1st class Delegate of Demand BG contractors Demand BG (Company A) Fig.3 Creation of area power demand forecasting value Overall plan

2nd class Indiv. Indiv. pertise of the operator so that the operator’s intentions company A company B Company ○Build-up can be reflected in the forecast results. plan creation There are two methods for forecasting demand. 3rd class Company Company One is a method in which the operator himself creates A plan B plan a forecast values by referring to actual past demand Consumer Consumer group Consumer results, actual weather results, and weather forecasts for the target day displayed on the screen of the power Dem. Dem. Dem. Dem. Dem. Dem. Plan Plan Solutions Contributing to Stable and Optimal Power Supply Energy creation creation demand-supply management system. The other method is to automatically calculate forecast values Power supply Power supply issue: Power Company B by using the system forecasting function. The system supply operator Gen. Gen. Gen. Gen. Gen. Gen. Only B company’s forecast function outputs the demand forecast for the demand result and plan current day, the next day and the day after the next day. Moreover, the current day forecasting is corrected Fig.2 ‌BG implementation achieved by hierarchical master one after another by obtaining the latest actual de- structure mand values every 30 minutes and the latest weather forecast. mand BGs, individual companies, and consumers and Four system forecasting methods are implemented power supplies. Each piece of master data is linked to as standard system forecasting functions. These in- its upper layer. By using this structure, the operator clude 3 simple forecasting methods based on the calen- can create plans independently on an individual com- dar and weather conditions: same operation day fore- pany basis. After this, the plans for each individual casts, same day of the week forecasts and similar day company are aggregated to create a plan for the entire weather forecasts. The other is a Just-In-Time (JIT) demand BG. Furthermore, the operator can revise the forecasting method utilizing an automatic factor analy- plan for the entire demand BG. sis. From these 4 methods, operators can choose a By using BG management authority setting, the method suitable for the demand characteristics of each planning and demand results of the individual com- forecast group using their own knowledge so that accu- pany can be published exclusively to the person in rate forecasting can be made for the whole area. charge of that individual company. We would now like to introduce Fuji Electric’s latest demand forecasting technology, “JIT Forecasting.” 2.2 Power demand forecasting technology JIT forecasting calculates forecast values using Setting up forecast groups of consumers catego- actual demand values of past days with similar condi- rized by their business characteristics having similar tions through the following 3 steps (see Fig. 4): demand-curves, users can forecast demand by the (a) Correlation factor analysis group. As shown in Fig. 3, the forecast results for each Automatically analyzes factors on a daily basis forecast group are aggregated, and demand forecast that have strong correlation with actual demand re- values are created for each area of TSO. In addition, sults it leaves room for the forecast values of the entire area (b) Similar day extraction to be corrected on the basis of the knowledge and ex- Uses the strongly correlated factors analyzed in

Power Demand-Supply Management System and VPP Solution 185 operating results when optimizing control variable, For past month considering generator operating conditions, such as

Result Correlation continuous operating constraints and continuous stop- Database factor Demand factor ping constraints. Demand analysis Humidity Temper- 3. VPP Solution ature Time Similar day Similar day demand Target day data extraction

Demand 3.1 Overview of VPP solution Weather Time VPP is a technology that controls demand-side forecast Temperature Demand DERs as if they were a single power plant by utilizing Temperature correction forecast value information and communication technology (ICT). Fuji Humidity JIT forecasting Demand Time function Electric has positioned large-capacity storage batteries Time as the future’s most important VPP energy resources Calendar information and is working to develop and provide a high-level resource aggregator (RA) system and resource system as a platform. By utilizing this technology, we are aim- ing to create a business service that provides system Fig.4 Just-In-Time (JIT) forecasting configuration operators with the 5 types of services shown in Table 4.

(a) to extract similar dates closest to the target fore- 3.2 Initiatives to utilize demand-side large-capacity cast date. storage batteries (c) Temperature correction Fuji Electric has been continuously developing Corrects the demand forecast values from the and demonstrating VPP functionality by participating difference between the actual temperature values in the “Kansai VPP Project” overseen by the Kansai of the similar days extracted in (b) and the forecast Electric Power Company, Incorporated, which is pro- temperature values of the target day. moted in the “Virtual Power Plant Construction JIT forecast can deliver forecasting results at high and Demonstration Project Using Consumer Energy speeds of consumer groups where it is difficult to ascer- Resources” started in FY2016 by the Ministry of tain the correlation between demand fluctuations and Economy, Trade and Industry. factors. (1) Configuration of large-capacity storage battery RA system 2.3 Technology for optimizing power generation plans Figure 5 shows the system configuration and Table Electricity utilities that supply electricity to vari- 5, the role of each component. Fuji Electric is de- ous generators and limited areas develop power gen- veloping a large-capacity storage battery RA server, 3 eration plans as a way to reduce fuel costs and CO2 OpenADR-MODBUS* conversion gateway (GW), VPP emissions. Fuji Electric’s technology for optimizing storage battery system and VPP controller. power generation plans(1) uses a linear programming (a) Large-capacity storage battery RA server to quickly create plans on a current day, next day and The RA server optimally distributes demand weekly basis. This planning system provides demand responses (DR) received from the higher-level ag- forecasting and the output forecasting of renewable gregation coordinator (AC server) to the large- energy sources, such as photovoltaic and wind power capacity storage batteries installed on the prem- generation. It also delivers start-up and stop plans ises of multiple DER owners. It also aggregates the of generators and storage batteries, as well as their results from resources to deliver them to the AC

Table 4 Service utilizing VPP Service Renewable energy Item Peak cut output suppression Demand response Planned-value Power system energy savings avoidance balancing adjustability Renewable energy Adjustability during Objective Power cost suppression avoidance Adjustability during Adjustability of BG tight power system reduction adjustability tight BG supply power imbalance suppression supply and demand Service Renewable energy beneficiary DER owners companies Power retailers Power retailers TSOs Demand increase / Demand increase / Demand increase / Control content decrease Demand increase Demand decrease decrease decrease Control cycle 30 minutes 30 minutes 30 minutes 30 minutes 1 to 30 minutes

*3: ‌MODBUS is a trademark or registered trademark of Schneider Automation, Inc.

186 FUJI ELECTRIC REVIEW vol.65 no.3 2019 operative capacity. The demand forecast used here

: Scope of *1 is JIT forecasting, which has undergone improve- Fuji Electric’s AC server development ment through smart community demonstration proj- OpenADR ects and power demand-supply management system Large-capacity Consumer-use Electric field testing by Fuji Electric. storage battery storage vehicle RA*2 server battery RA servers Furthermore, in order to improve the control ac- RA servers OpenADR curacy, we have implemented a forecasting function Internet of photovoltaic power generation used(2) for utility customers. Typically, DER owner demand is con- EMS VPP trolled by the amount of power received. Since pho- Gateways controllers tovoltaic power generators installed by DER owners MODBUS/TCP MODBUS, etc. are included on the demand side, this tends to in- Industrial-use Industrial-use Industrial-use crease the error in demand forecasting. Our system storage battery storage battery storage battery VPP storage systems systems systems battery systems forecasts the amount of power generated by the pho- Basic When resource When resource Fuji Electric tovoltaic power generators installed by DER owners configuration cannot receive cannot implement storage battery OpenADR VPP systems to improve demand forecasting accuracy and control accuracy. *1 AC: Aggregation coordinator *2 RA: Resource aggregator (b) OpenADR-MODBUS conversion gateway RA servers and resources are connected using Fig.5 ‌Configuration of large-capacity storage battery RA the OpenADR protocol in accordance with the guide- system lines of the Ministry of Economy, Trade and Indus- try. However, OpenADR requires mutual authenti- Table 5 ‌Table of large-capacity storage battery RA system cation using encryption and electronic certification. sharing functions Therefore, it is difficult to receive OpenADR directly Component Role when there is only a controller on the resource side. ◦ Connection with service providers To easily connect with RA servers, we have devel- and reception of DR (supply and de- oped the GW that converts OpenADR to MODBUS/

Aggregation mand adjustment) Solutions Contributing to Stable and Optimal Power Supply Energy coordinator (AC) ◦DR activation and DR distribution TCP. This gateway has greatly reduced the hurdles to RA surrounding the use of battery resources in VPP, Summary of all RA results issue: ◦ and has facilitated the use of more resource groups ◦Demand forecasting, photovoltaic power generation forecasting in VPP. Large-capacity DR cooperative capacity calculation (c) VPP storage battery system storage battery RA ◦ DR distribution to each resource server ◦ A VPP storage battery system controls the per- ◦Summary of underlying resource results missible amount of charging and discharging accord- Gateway (GW) ◦OpenADR-MODBUS/TCP conversion ing to measures, such as peak-cut, during normal operations to support VPP. When DR is activated, ◦Local control such as peak cut ◦Charging and discharging control it performs high-precision monitoring and control VPP storage battery based on DR to coincide the power system interconnection point system ◦Creation and notification of operation plans with the DR value by controlling charging and dis- ◦RA server linkage function charging using forecasting in consideration of vari- ◦Same functionality as VPP storage ous constraints. These operation typically requires battery system VPP controller an energy management system (EMS) and control- ◦Interface with conventional battery systems lers. Fuji Electric has developed a controller with built-in EMS functionality to share communications function with RA servers, helping achieve these server. Whereas storage batteries have the conve- functions needed. It is provided as a standard pack- nience of instantaneous control in both the charging age and has been released to the market as a VPP and discharging direction, charging and discharging storage battery system. times are limited since they depend on the capac- (d) VPP controller ity of the storage battery and the state of charging. For storage battery systems that do not come Therefore, when distributing DR, it is important with the advanced functions required by VPP, to estimate the cooperative capacity of the DR for we have developed a controller that implements each time zone by monitoring the status of each re- VPP logic for achieving the same functions as Fuji source. In order to do this accurately, the RA server Electric’s VPP storage battery system and the inter- forecasts the power consumption of each utility face for conventional storage battery systems. customer for each time zone, determines the refer- (2) VPP challenges and measures ence value of DR, plans the change of state of charge When there are many resources with large demand (SOC) for the storage battery, and estimates the co- fluctuations or when the demand forecasting- accu

Power Demand-Supply Management System and VPP Solution 187 PPS base

Power retail Utility customer energy Utility customer management service Power retail Before plan revision energy management service A. demand suppression B. DER Power demand-supply Large-capacity storage battery : Demand increase management system RA system location request and activation (resource) suppressible amount calculation (Supply and demand ○BG imbalance suppression Demand (1) Procurement management) adjustability (Power cost reduction) plan shortage calculation (3) Demand suppression (4) Suppression request study amount, target period A. Demand (3) Demand suppression B. Resource kWh Procurement request verification suppression study request suppressible (2) Calculation of (11) Demand suppression plan demand suppression request and amount activation activation calculation Time amount and target (5) Resource status period D. Demand C. Demand verification suppression suppression ○Charging and result (7) Demand suppressible control discharging plan verification amount report Plan revision (7) Demand ○Present state (15) Demand suppression (8) Suppressible suppressible ○Future state results report Demand plan amount verification amount report (6) Suppressible amount,

kWh period calculation Procurement (9) Demand plan plan revision Consumer group (13) Storage battery control (11) Demand Time C. demand suppression Utility (10) Demand activation suppression control DER suppression activation customer (12) Allocation of suppression amount to each resource VPP storage battery systems Imbalance verification D. demand suppression (15) Demand result verification suppression ○Battery status and output Demand result (16) Demand results report (13) Storage battery ○Interconnection point suppression control instantaneous value result verification ○Demand suppression kWh Procurement control response plan (14) Result verification (17) Imbalance Time verification

(b) Demand suppression utilizing power demand-supply system and (a) Business process flows of during demand suppression large-capacity storage battery RA system

Fig.6 Power utility VPP solution combining demand-supply management system racy deteriorates, it becomes difficult to control power within the target value. As a countermeasure, we are 4. Postscript working to improve forecasting accuracy and provide feedback control throughout the entire resource group. In this paper, we introduced our power demand- Furthermore, we plan to examine the evaluation supply management system and VPP solution. index for contributing to the supply and demand ad- Electricity System Reform is intended to open justment of each resource in VPP demonstration proj- up new power markets, such as a base-load market, ects in consideration of the balancing market that will real time market and capacity market. Furthermore, be established in the future. we expect the external environment to continuously change since the business policies of electricity utilities 3.3 Power utility VPP solution combining demand-supply are also being influenced by the “Act on the Promotion management system of the Use of Non-Fossil Energy Sources and Effective Figure 6 shows the VPP solution for PPSs. This Use of Fossil Energy Source Materials by Energy Sup- solution is designed to enable the retailing section of pliers” (Act on Sophisticated Methods of Energy Sup- power producers and suppliers to minimize imbalance ply Structures), which seek to reduce environmental costs by utilizing storage batteries through the utility burdens. customer energy management system to suppress the In response to these changes, we will continue to demand of customers. This will enable utility custom- study and create services that maximize the profits of ers to receive benefit from contribution costs based on electricity utilities. their contribution. When a shortage imbalance, which is a state in which the demand forecast is larger than References the actual demand, is expected to increase, the large- (1) Katsuno, T. et al. Supply and Demand Control System capacity storage battery RA system receives a demand for Power Systems with Distributed Power Supplies. suppression request from the power demand-supply FUJI ELECTRIC REVIEW. 2013, vol.59, no.3, p.191- management system and controls the utility custom- 195. er’s storage batteries to suppress the imbalance. In (2) Ishibashi, N. et al. Photovoltaic Power Generation addition, the effect of introducing storage batteries is Forecasting Technology for Supporting Energy Man- improved by providing multiple services, for example, agement Systems. FUJI ELECTRIC REVIEW. 2013, it is used for customer services, including a peak cut vol.59, no.3, p.196-200. and energy saving, during normal times.

188 FUJI ELECTRIC REVIEW vol.65 no.3 2019

Table 1Line-upof1,700-VX-SeriesIGBTmodules FUJI ELECTRICFUJI REVIEW (2) (1) the featuresareasfollows. Series,” “V conventional the with Compared modules. 1. IGBT modules. “X-Series” 7th-generation the of products 1,700-V oped of devel has reliability Electric Fuji higher equipment, conversion power and consumption power lower highly be to reliable. needs also infrastructure, constitutes social which of equipment, part above the time, modules, same (IGBT) the At equipment. such in transistor devices key as serve which bipolar gate insulated large-capacityfor demand growing is there in and crease, to tends equipment conversion power of piece per beingexpanded.tionisAccordingly, outputthecurrent as genera such photovoltaicpower andgeneration power energywind renewable of im utilization being and is proved, efficiency conversion Energy warming. CO 1,700-V Line-Upsof7th-Generation“XSeries”IGBT *

Electronic DevicesBusinessGroup, FujiElectricCo.,Ltd. * 2 PrimePACK™ isaTrademarkorregisteredtrademark ofInfineonTechnologiesAG. Package PrimePACK™ Table 1 Table current, output higher a for demands meet To reduce to necessary become has it years, recent In Features msin i trs f esrs gis global against measures of terms in emissions operation nrae n ucin eprtr a continuous at temperature junction in Increase Increase inoutputcurrent Std. 2in1 Dual XT Rated current shows the line-up of 1,700-V X-Series IGBT X-Series 1,700-V of line-up the shows (A) T ＊ vjop 15 NAGAI, Daishi no.3 vol.65 25 35 2019 50

75 MASUDA, Shinichi 34 mm 100 Modules 2019-S03-1 - - - - 150

62 200/ 225 ae tinn tcnlg ae ple. Therefore, applied. are technology thinning the wafer and technique miniaturization latest the Series X IGBTs, In energy. recovery reverse the and (FWD) diode wheeling free the of voltage forward the between turn-off the and and energy, IGBT the of voltage saturation the XT (M254) packages. Dual using V 1,700 of voltage rated a and A 450 of current rated a the with modules to the refers comparing of following result X The applying technology. by chip Series Series) (V products conventional with compared the reduced greatly been has dissipation 2. sumption. Compared with the V Series, the power con power the Series, V the with Compared sumption. energy isreducedbyapproximately17%. recovery reverse the and formed reverse is waveform smooth recovery a control, time life the optimizing by addition, apply In technology. by thinning wafer V latest the ing 0.2 approximately by reduced is voltage forward the FWDs, series X the In improvement. great a in resulting 12%, approximately by energy, turn-off the and V 0.4 approximately by reduced been has age volt saturation the IGBTs, Series V the with compared mm Dual XT Conventional line-up Figure 1 Figure power the modules, IGBT Series X 1,700-V the In Figure 3 Figure Electrical Features 300

80 mm YOSHIDA, Kenichi 400/ 450 shows the results of calculating power con power calculating of results the shows shows the trade-off characteristic between characteristic trade-off the shows i. 2 Fig. PrimePACK™2 600 hw te rd-f characteristic trade-off the shows 650 7th generationexpandedline-up PrimePACK™3 1,000/ 1,200

1,400 1,800 2,000 189 - - - -

New Products X Series: 2MBI450XNA170-50 Conventional product: 2MBI450VN-170-50 3. Packaging Technology V CC = 900 V, I C = 450 A, V GE = ±15 V, T vj = 150ºC, dv/dt = 10 kV/µs 250 To further improve the output current, the junction Measurement point 230 temperature of the X Series at continuous operation Estimated value 210 (T vjop) is increased from 150 °C (conventional product) 190 to 175 °C. To increase T vjop, it is necessary to improve 170 the ΔT vj power cycle capability, which is lifetime with 150 Conventional respect to the temperature change, and the heat re- product 130 X Series sistance property of insulation silicone gel, which af- 110 fects the long-term reliability at high temperature. A 90 Saturation voltage: Approx. 0.4-V reduction newly developed solder material and new wire bonding Turn-off energy (mJ/pulse) 70 Turn-off energy: Approx. 12% reduction technology on semiconductor chips are applied to the 50 1.8 2.0 2.2 2.4 2.6 2.8 X Series. Thus, compared with the conventional prod- Saturation voltage (V) uct, the T vj power cycle capability has been improved by approximately twice under the condition of T vjmax Fig.1 Trade-off characteristics (IGBT) = 175 °C and ΔT vj = 50 °C. In addition, by adopting new silicone gel with a high heat resistance property, gel hardening under the environment of 175 °C is con- X Series: 2MBI450XNA170-50 Conventional product: 2MBI450VN-170-50 trolled and a long-term insulation performance is en- V CC = 900 V, I C = 450 A, V GE = ±15 V, T vj = 150ºC, sured. dv/dt = 10 kV/µs Moreover, a high heat-radiating insulating sub- 160 Measurement point strate using AlN with high thermal conductivity is 140 Estimated value applied to efficiently dissipate the joule heat of semi- 120 conductor chips. Figure 4 shows the transient thermal 100 Conventional resistance characteristics. Compared with the conven- product 80 X Series tional product using an Al2O3 insulating substrate, the 60 thermal resistance between the junction and the case has been reduced by about 45% with the same chip 40 Forward voltage: Approx 0.2-V reduction size. 20 Reverse recovery energy: Approx 17% reduction Figure 5 shows the results of calculating the output

Reverse recovery energy (mJ/pulse) 0 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 current of an inverter and the junction temperature of Forward voltage (V) an IGBT, in the X Series module having the maximum rated current of 600 A and V Series module having the Fig.2 Trade-off characteristics (FWD) maximum rated current of 450 A of the Dual XT packages. Compared with the conventional product, the output current of the 1,700-V X Series products has X Series: 2MBI450XNA170-50 Conventional product: 2MBI450VN-170-50 been improved by approximately 30% by applying the V CC = 900 V, I C = 225 A, V GE = ±15 V, T vj = 150ºC, latest X Series chip technology and package technology Modulation rate = 1, cos φ = 0.9, f O = 50 Hz, dv/dt = 10 kV/µs 1,000 described above. The product can meet demands such 900 9% reduction as miniaturization of conversion equipment, lower Conventional 800 product power consumption and higher reliability. X Series 700 10% reduction 600 10 500 Comparison with the same chip size 400 13% reduction P rr 300 P 45% reduction f 1.0 P on Al2O3 insulating substrate

Power consumption (W) 200 P off 100 P sat 0 AlN insulating substrate f c = 1 kHz f c = 3 kHz f c = 5 kHz 0.1

Fig.3 Power consumption junction and case (a.u.) Thermal resistance between

0.01 sumption of the X Series has been reduced by approxi- 0.001 0.01 0.1 1.0 mately 13% under the condition of a carrier frequency Pulse width (S) of 1 kHz. Fig.4 Transient thermal resistance characteristics

190 2019-S03-2 FUJI ELECTRIC REVIEW vol.65 no.3 2019 X Series: 2MBI600XNE170-50 Conventional product: 2MBI450VN-170-50 Launch time V CC = 900 V, V GE = ±15 V, Modulation rate = 1, cos φ = 0.9, Starting in June 2019 f C = 3 kHz, f O = 50 Hz, T a = 50ºC 200

175 Product Inquiries Business Planning Department, Electronic Devices 150 Business Group, Fuji Electric Co., Ltd. Conventional product 125 Tel: +81-263-27-2943

100 +30% 75 X Series IGBT junction temperature (°C) 50 0 50 100 150 200 250 300 350 400 Output current (A) New Products Fig.5 ‌Output current of inverter and junction temperature of IGBT

1,700-V Line-Ups of 7th-Generation “X Series” IGBT Modules 191 Storage Battery Systems That Reuse EV Batteries

YAMANO, Hiroyuki * MIYAMURA, Naotaka * MATSUI, Hiroshi⁑

With the spread of electric vehicles (EV) in recent years, a system for safely and effectively utilizing bat- 3φ3W 6,600 V Commercial system Protective relay teries used in EVs is being established. Utilization of a On the other hand, storage battery systems for spare feeder is assumed. utility customers were used to reduce the contract Service provision Protection demand by cutting the peak of power consumption to range relay UPS save energy costs. If the results of the virtual power Vacuum magnetic contactor General Important plant (VPP) demonstration project of the Ministry load load of Economy, Trade and Industry, which started in For boost-up General For load FY2016 and planned to continue until FY2020, are control systematized, utility customers can acquire income be- power PCS supply sides the limit on the maximum power consumption, UPS Control and the effect of investment-return will be higher. device This system is a storage battery system for utility Storage battery container customers equipped with used EV storage batteries Main components Specifications that has functions for supporting peak cut, VPP, and Storage battery container 20 ft, 400 kWh business continuity plans (BCPs). Figure 1 shows the Storage battery PCS 400 kW appearance. Booster transformer Oil-filled, 400 kVA 6.6 kV/170 V Vacuum magnetic 7.2 kV, 600 A 1. System Configuration contactor panel Control system Peak cut, VPP function This system has been created by combining a 20-feet container that stores the used storage batter- Fig.2 ‌System configuration and specifications of main compo- ies provided by 4R Energy Corporation by twice the nents loading efficiency of the conventional one with Fuji Electric’s power conditioning systems (PCSs) and con- Electric has developed a standard package with Sumi- trol systems. Figure 2 shows the system configuration tomo Corporation and Japan Benex Corporation to re- and the specifications of main components. duce the costs. The system can be customized accord- Conventionally, storage battery systems were pro- ing to the customer’s request. posed according to each customer’s request. Fuji 2. Space-Saving Design

The storage battery packs will be used in the state they were mounted on EVs to utilize the safety technology of automobile parts. A storage battery container with great safety and mounting density has been co-developed by making full use of the high loading technology for containers. As shown in Fig. 3, the conventional 20-feet container stores 12 packs (approximately 200 kWh), where as the new model stores 24 packs (approximately 400 kWh).

Fig.1 Used EV storage battery system

* Power Electronics Systems Energy Business Group, Fuji Electric Co., Ltd.

⁑ Sales Group, Fuji Electric Co., Ltd.

192 2019-S04-1 FUJI ELECTRIC REVIEW vol.65 no.3 2019 Peak cut Conventional storage battery container 500 90 Actual demand Demand amount result 80 400 Target demand 70 300 60

200 Recovery of 50 Used storage batteries: stores 12 packs remaining battery 40 Rated storage battery capacity: 288 kWh 100 Discharged Electric energy (kW) Remaining amount Remaining battery (%) Effective storage battery capacity: approximately 200 kWh battery 30 0 Photovoltaic power 20 generation amount Charged amount −100 10 New storage battery container 4:00 5:00 6:00 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00

Fig.4 Example of peak-cut operation New Products leased, the storage battery PCS is switched to the self- Used storage batteries: stores 24 packs support operation and activated to supply power. Rated storage battery capacity: 576 kWh (3) VPP Function Effective storage battery capacity: approximately 400 kWh Figure 5 shows the basic configuration diagram of VPP. As shown in the figure, VPP is a technology for Fig.3 Mounting design of storage battery container bundling resources of utility customers (equipment such as an ESS) and controlling them like one power plant as an adjustment power of the power system. By 3. Functions this technique, storage batteries charge and discharge according to the signals from the higher level system. The following refers to the overview of the system Thanks to VPP, compensation can be expected in the functions. future. (1) Peak cut and peak shift Fuji Electric is participating in the VPP demon- Using the electric power storage system and peak stration project of the Kansai Electric Power Group, cut and peak shift operations helps reduce the contract and this system incorporates the function that sup- demand, basic charge, and electricity rate. Certain ports this demonstration project. Therefore, the utility cost reduction effect is expected although it depends on customers purchasing the system can participate in how customers use power. Figure 4 shows an example the VPP demonstration project and can apply for subsi- of peak cut operation. dies to reduce the initial costs. (2) BCP (4) Effective Utilization of Renewable Energy The system can be used as a backup power supply As shown in Fig. 6, the solar power generation for that is necessary for stable and continuous business self-consumption may be surplus in a low-demand time operation. Specifically, when the commercial power zone on weekends. Renewable energy can effectively fails, the linkage switch of the commercial power is re- be utilized by charging this surplus power in storage

Host system Aggregation coordination (AC) server: User (service user) IF, allocation to RA server, integrated operation AC server Resource aggregation (RA) server: RA server AC server IF, allocation to each resource (ESS), integrated operation

Energy management system (EMS): Controller for the battery system I/F for VPP control of utility customers (general private demand), base line EMS calculation of power demand at the power receiving point, controller related to PLC control of ESS such as demand forecast (limit on maximum power consumption and peak load shifting, BCP self-support operation control, calculation of chargeable and dischargeable amount, etc.) PCS Power conditioning system (PCS): Storage battery Fuji Electric's AC-DC converters with 400 kW, 500 kW, 600 kW, and 750 kW

ESS of utility customer Storage battery: Supports various storage batteries (LiB, NAS, RF, Pb, etc.)

Fig.5 Basic configuration diagram of VPP

Storage Battery Systems That Reuse EV Batteries 2019-S04-2 193 Rooftop solar panels

Surplus

Consumption Charge

Plant Used storage batteries

200 90 Demand result Photovoltaic power generation amount 80 Fig.7 Example of system monitoring screen 100 70

Discharged 60 amount 0 50

40 Charged amount Electric energy (kW) −100 30 Remaining battery (%)

Remaining battery 20 −200 10 4:00 5:00 6:00 7:00 8:00 9:00 10:00 11:00 12:00

Fig.6 Example of effective utilization of renewable energy batteries and discharging it in a time zone with high demand. [ min ]

4. Human Machine Interface

The control system is equipped with the touch Fig.8 Example of demand monitoring screen panel on the front panel whose screens are used for the operation and maintenance of the storage battery system using the screens. Thus, visibility and operability Launch time are greatly improved, and the system allows intuitive June 2018 operation without depending on the instruction manual. Figure 7 shows an example of a system monitoring screen that allows power system state monitoring and Product Inquiries remotely opening and closing high voltage switches, Sales Department IV, Energy Solution Division, and Fig. 8 a demand monitoring screen that can moni- Sales Group, Fuji Electric Co., Ltd. tor the actual load per 30-minute demand and charge Tel: +81-3-5435-7028 and discharge of storage batteries.

194 2019-S04-3 FUJI ELECTRIC REVIEW vol.65 no.3 2019

* Table 1Productappearanceandline-up Fig.1 SchematicdiagramofRC-IGBchip FUJI ELECTRICFUJI REVIEW cal innovationofchipsandpackages. technologi the by reliability having and output power modules higher IGBT Series” “X 7th-generation the commercialized has Electric Fuji reliability. and put out power higher have to required are modules IGBT therefore, reliability; high have and low-cost and small renewable and energy. automobiles such consumers, fields industry, of variety as wide a in used system version con power a for device key a as increasing is ductors, bipolar gate semicon power are insulated which modules, for (IGBT) transistor demand a these, Among energy. electrical converts efficiently that technology electronics power the for growing are expectations high society, sustainable and responsible create and control CO by economic warming global and prevent To increase growth. population of because world * PrimePACK™: Trademarkorregistered trademarkofInfineonTechnologiesAG 1,200 V Product appearance

Electric Co.,Ltd. oe Eetois ytm Eeg Bsns Gop Fuji Group, Business Energy Systems Electronics Power e eeoe a ees-odcig GT (RC- IGBT reverse-conducting a developed We becoming are systems conversion power Recent the in increasing steadily is demand energy The 7th-Generation “XSeries”1,200-V/2,400-A X Series V Series TAKASAKI, Aiko IGBT no.3 vol.65 + FWD 2019 Conventional product RC-IGBT Modules V - IGBT +V *

1,400 RC 2 emission - KAKEFU, Mitsuhiro IGBT - FWD X 89 - IGBT +X 2019-S06-1 - - - - - FWD * GT hvn te ucin o a IB ad free a and in shown IGBT as chip, one on an (FWD) diode wheeling of functions the having IGBT) 1. Series” “X 7th-generation RC-IGBT modulewedeveloped. the of A V/2,400 1,200 with with theconventionaltechnology. difficult been had which output, power higher having product new has a developed before have we and as increased, been size same the having product new the of current rated the result, a As module. IGBT the in mounted chip semiconductor the of reduced current been rated has per area total the technology, Series X above the and technology RC-IGBT the combining By IGBT has the functions of an IGBT and a FWD on one on FWD a and IGBT an of functions the RC- has IGBT The antiparallel. in connected was which FWD, a and IGBT an chips: two required product ventional con The RC-IGBT. Series X the of circuit equivalent 2.1 2. A. (maximum) to2,400 A 1,800 from increased been has V 1,200 of voltage ing block a having product the of current pack rated the and ages, RC-IGBTs of innovation technological the With product. developed the and product conventional 250 1: ‌ of InfineonTechnologiesAG. PrimePACK™ is a trademark or a registered trademark registered a or trademark a is PrimePACK™ hs eiw ecie te “PrimePACK™* the describes review This iue 2 Figure 1 Table Chip Technology Features Applied Technology Rated current(A) 1,800 *

PrimePACK™ hw te perne n ln-p f the of line-up and appearance the shows (Unit: mm) hw te rs-etoa srcue and structure cross-sectional the shows YAMANO, Akio * 3 Developed product 89 X * -

RC 2,400 - IGBT 250 PrimePACK™

(Unit: mm) Fig. 1 Fig. 1 3 195 * 3+ + ” - - - .

New Products mized the wire bonding and developed solder materials p+ Emitter and silicone gel materials to solve the above problems. n+ Further, by adopting an AIN insulating substrate

Gate with high heat dissipation, the heat resistance between p base the chip bonding parts and the case has been reduced, improving the heat dissipation. These technological innovations for the X Series FWD IGBT Current achieve both of power output increase and high reli-

I C I RC ability. Field stop layer 3. Power Output Increase by Terminal Temperature Decrease p+ collector n+ cathode (a) Schematic structure of RC-IGBT chip To achieve high power output, it is necessary to in-

Emitter crease the current capability of packages in addition to improving the characteristics of semiconductor chips. This is because the terminal temperature can exces- Gate sively rise when large output current flows. As shown in the white box of the product appearance in Table 1, the developed product has two terminals, whereas the conventional product has one termi- Collector nal, to suppress the terminal temperature increase. (b) Equivalent circuit of RC-IGBT Figure 3 shows the results of evaluating the terminal temperatures of the conventional product and Fig.2 Cross-sectional‌ structure and equivalent circuit of the the developed product. The developed product has an 7th-generation “X Series” RC-IGBT increased number of terminals and can distribute the current when electricity is turned on. This decreased chip, and thus it can turn on electricity in both the for- the terminal temperature by 50 °C compared with the ward and reverse directions with one chip in the same conventional product. way as the conventional product. Thus, the heat generation caused by the current In addition, by applying the chip technology that flowing through the terminals has been greatly re- makes the surface structure smaller and the wafter thinning technology, the X Series IGBT module has collector-emitter saturation voltage V CE(sat) that is Current out Current in smaller than that of the conventional “V Series” by Input side bus bar approximately 0.6 V in the same switching energy E off. Output side Applying the wafer thinning technology generally in- bus bar volves the risk of blocking voltage drop and current and voltage oscillation at the time of turn-off. To solve these problems, we suppressed the blocking voltage drop and oscillation by optimizing the field stop (FS) Outside of output terminal Input terminal layer provided on the back surface, which is the chip (a) Evaluation on actual machine technology of the X Series. 200 Newly developed 175 product (inside of 2.2 Package Technology output terminal) 150ºC To further increase the power output of the X Se- 150 Newly developed product (outside Decrease by 50°C ries IGBT modules, the chip bonding temperature T vjop 125 of output terminal) Conventional at the time of operation is increased from 150 °C of the 100 product 100ºC conventional V Series to 175 °C. However, the increase 75 in the operation guarantee temperature leads to dete- 50 rioration in the strength of the material and increase 25 in thermal stress. Therefore, there is a concern that 0 the aluminum wire bonding parts and the solder bond- 0 500 1,000 1,500 2,000 Temperature of output side bus bar (°C) ing parts on the chip may deteriorate rapidly, shorten- Direct current (A) ing the product lifespan. In addition, silicone gel gen- (b) Evaluation result erally involves a concern that the gel gets torn and the insulation performance deteriorates under in a high Fig.3 ‌Results of heat-run evaluation and terminal temperature temperature environment. In the X Series, we opti- evaluation

196 2019-S06-2 FUJI ELECTRIC REVIEW vol.65 no.3 2019 duced compared with the conventional product, and the X Series can exhibit higher output with this higher Calculation conditions Modulation mode: 3 arms, f O = 50 Hz, V DC = 600 V, current capability. power factor 0.9, control factor 1.0, (°C) V GE = +15 V / −15 V, R G = on 0.22 Ω / off 0.22 Ω

vjmax 200 4. Features of “1,200-V/2,400-A” IGBT Modules 175 X Series As described above, the RC-IGBT has a smaller 150 1,200 V / 1,800 A (conventional product) total area of the semiconductor chip compared with 125 the conventional combination of an IGBT and a FWD. 100 However, when compared to the IGBT chip and FWD 23% chip in the conventional product individually, the RC- 75 X Series RC-IGBT IGBT has a larger chip area. Therefore, the RC-IGBT 50 1,200 V / 2,400 A 1,220 1,500 has lower heat resistance between the chip bonding (newly developed product) 25 parts and the case compared with IGBTs and FWDs, 0 200 400 600 800 1,000 1,200 1,400 1,600 1,800 Output current I out (rms) (A) and therefore, it has excellent heat dissipation capabil- Maximum IGBT bonding temperature T ity. New Products Figure 4 shows the calculation results of power con- Fig.5 ‌Relationship between output current and maximum IGBT sumption during inverter operation. bonding temperature The developed product shows almost the same inverter power consumption as the conventional product. This equivalent power consumption and high heat dissipation capability, which is the feature of the RC- IGBT, reduces T vjmax of the developed product by 31 °C Calculation conditions compared with the conventional product. Modulation mode: 3 arms, f O = 50 Hz, V DC = 600 V, (°C) I C(rms) = 1,200 A, power factor 0.9, control factor 1.0, Next, Fig. 5 shows the calculation results of the V GE = +15 V / −15 V, R G = on 0.22 Ω / off 0.22 Ω

vjmax inverter output current and the maximum IGBT bond- 3,000 200 Decrease 171 ing temperature T vjmax. When the developed product 2,500 by 31°C is adopted, the output current of the power conversion 140 150 2,000 system can increase by 23% compared with the con- 1,531 1,520 ventional product. 1,500 100 1,000 Launch time 50 500 January 2020

Inverter power consumption (W) 0 0 X Series RC-IGBT X Series 1,200 V / 2,400 A 1,200 V / 1,800 A (newly developed product)(conventional product) Product Inquiries Maximum IGBT bonding temperature T FC 3 kHz Sales Department I, Sales Division, Electronic Powering Devices Business Group, Fuji Electric Co., Ltd. Tel: +81-3-5435-7152 Fig.4 ‌Calculation results of power consumption during inverter operation

7th-Generation “X Series” 1,200-V/2,400-A RC-IGBT Modules 197

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2019 Vol.65 No. 3 Energy Solutions Contributing to Stable and Optimal Power Supply

Energy Solutions Contributing to Stable and Optimal Power Supply Vol.65 No.3 2019

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