Demonstration Project utilizing Hybrid Storage Battery System in the Oki-islands Subsidized project of Ministry of the Environment

June 16, 2016 Power System Division The Chugoku Electric Power Co., Inc. 1

１．Overview of the Oki-Islands Overview of the Oki-islands 2  The Oki-islands are located in the Sea of , about 50km to the north of Shimane Peninsula.  Composed of the “Dozen” and “Dogo” and about 180 small islands.  The total area is about 350km2. A population is about 21,100 (Dozen: about 6,100, Dogo: about 15,000).  Fisheries, agriculture and forestry, tourism are their major industries.

【Dozen】 【Dogo】 Oki-Islands UNESCO Global Geopark （Nishinoshima） September 2013 Certified as Global Geoparks November 2015 Global Geoparks confirmed as （Ama） Dogo （Chibu） （Okinoshima） UNESCO Global Geoparks

The Oki-Islands

(Source: Wikipedia, Japan natural location map with side map of the Ryukyu Islands.jpg) Matengai（Nishinoshima） Rousokuiwa（Dogo） Electrical power supply facilities 3 and demand in the Oki-Islands (Before start of project)

 2 internal combustion power plants(heavy oil diesel) “Saigo” and “Kuroki”, supply almost all the electricity with 22kV tie line.  Maximum Power demand is about 24ＭＷ，minimum is about 10ＭＷ. Prefectural Ohmineyama Plant (wind) Dozen (Three 600-kW towers for 1.8 MW total) Total capacity: 7.38 MW Minamitani Plant Maximum demand (hydroelectric run-of-river) during 2012: 7.3 MW (0.1MW)

Yui Plant Kuroki Plant (hydroelectric dam) Dogo (internal combustion) (0.2 MW) Dogo (7.38 MW) Total capacity: 25.32 Saigo-Kuroki submarine MW power cable (22kV,18km) + Wind, Hydro Maximum demand during 2012: 16.8 MW

Dozen Saigo Plant (internal combustion) (25.32 MW) Total capacity: 32.70MW + wind, hydro maximum demand during 2012: 24.1 MW Renewable energy in the Oki-Islands 4 （Before start of the project） wind power plant hydroelectric plant residential PV （1.8 ＭＷ） Shimane Prefectural （0.3 ＭＷ） （about 0.8 MW) Bureau of Enterprise The Chugoku Electric Power (As of Jan. 2014）

Large fluctuations between seasons Large-scale Demand introduction of Characteristic （Surplus power generation will renewable energy occur during light-load seasons） used to be difficult Seasonal typical demand-curves in 2012 22.0 Spring(May)春（５月） 20.0 Summer(August)夏（８月） Autumn(October)秋（１０月） 18.0 Winter(January)冬（１月） （MW） 16.0

14.0

12.0

10.0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 (Hours) 5

２．Overview of demonstration Project utilizing Hybrid Storage Battery System Challenges for large renewable energy 6 penetration in the Oki-Islands Short term fluctuation Long term fluctuation Output fluctuation of RE Output fluctuation of RE due to such as a change in the due to such as transit of cloud position of the sun

Lack of frequency regulation Surplus power generated capacity

Renewable energy 〔MW〕 Increase of Renewable energy output fluctuation Photovoltaic Use of surplus power at night time demand

Base-load generation

3 6 9 12 15 18 21 24 〔Hours〕 Concept of Hybrid Storage Battery System 7

Countermeasure of short Countermeasure of long term fluctuation Problem term fluctuation

Simultaneous solution

Hybrid Storage Battery System Lithium ion battery(Li-ion) Sodium-sulfur battery(NAS)

Output Increase of Fast and small fluctuation Renewable energy ↓ Small capacity and high-output [Fast and small fluctuation] Demand ex.)Fluctuation Lithium ion battery（Li-ion) curve by passing cloud

Renewable energy (existing) Coordination Base-load generation Time Slow and large fluctuation ↓ Large capacity [Slow and large fluctuation] → use PV output at night ex.)Fluctuation by locating sun Sodium-sulfur battery（NAS) Outline of the Demonstration Project 8

 Period : From September 2015 to March 2019 （3.5 years）  Items: ① Coordinated control between storage battery and diesel generation ② Charge/discharge control technology in order to take full advantage of the storage battery capacity ③ Output allocation of the lithium-ion and the NAS batteries

Hybrid Storage Battery System Prefectural Ohmineyama Plant (wind) (Three 600-kW towers for 1.8 MW total) Type Output Capacity NEW NAS 4,200kW 25,200kWh 西ノ島変電所西ノ島変電所 residential Li-ion PV Minamintani Plant 2,000kW 700kWh (hydroelectric run-of-river) 500kW (0.1MW) NEW Yui Plant (hydroelectric dam) Nishinoshima Kuroki Plant (0.2 MW) (internal combustion) substation (7.38 MW) Hybrid Storage Dogo Battery System 6,200kW

Saigo-Kuroki submarine power cable (22kV,18km)

Saigo Plant (internal combustion) NEW (25.32 MW) Dozen Large-scale NEW NEW PV Plants Large-scale 3,000kW PV Plant Ama 2,000kW Plant(wind) 2,000kW Renewable energy introduction plan 9

 Aiming at 11MW of total renewable, by newly introducing 8.0MW in addition to the existing 3.0MW, by utilizing the storage battery system.

Record Supply and demand image Renewable energy Plan 〔MW〕 at the time of the facilities 〔MW〕 As of March 31, ） 2016 minimum demand

MW Wind power 1.8 1.8 （

About About Before the start Residential PV of the 0.8 0.8 Storage battery absorb the surplus demonstration power generated by Renewable project Hydroelectric power 0.3 0.3 renewable energy energy About About Subtotal 11 3.0 3.0 About Large scale PV 3.0 Minimum 5.0 demand After the start Wind power plant 2.0 0.0 10 of the Operational demonstration About About0. Residential PV required minimum project 0.5 3 output of the internal-combustion About About power Subtotal 8.0 3.3 About About Total Demand Power supply 11.0 6.3 Installed facilities and equipments 10 Designed as compact as possible, considering safety measures for NAS characteristics and noise mitigation for neighbor residences.

The Nishinoshima substation

PCS for NaS batteries NaS batteries Control NaS batteries room NAS batteries NaS batteries Lithium-ion 4,200kW NaS batteries batteries 25,200kWh PCS for Lithium-ion batteries Grid- Lithium-ion batteries Grid-connection connection 2,000kW equipment equipment Transformers 700kWh 7,500kVA

Site area：about 2,400㎡ Benefits of hybrid scheme for storage battery system 11

Combination of different types of storage battery system

Improvement of Improvement of charge/discharge management Initial cost of NAS batteries reduction system efficiency

■In hybrid storage battery ■Combination of Li-ion system, the frequency of SOC ■Reduction of auxiliary and NAS battery can reset can be increased by sharing power consumption can decrease construction the absorbing capacity for RE be achieved by reducing cost, because ¥/kW of Li- output fluctuation between NAS the capacity of NAS ion and ¥/kWh of NAS are and Li-ion battery, and SOC battery, that improves economical. operational range is possible to the system efficiency of expand. storage battery system. Cost reduction

SOC Operational range (NAS only : SOC reset once a week) Expandable Expandable

SOC Operational range (Hybrid storage battery system: SOC reset twice a week)

Discharge end Charge end about 30% 12 Optimal combination of the storage battery capacity

 Amount of acceptable renewable energy and the required power output and capacity of storage battery system have been determined by simulation.  Alternative No. 2 in following table was selected.

Output [MW] Simulation result Alternatives Cost Li-ion NAS Capacity Charging/Discharging Frequency Battery Battery of tie-line fluctuation deviation

Battery Capacity No. 1 1.5 4.8 within the range

Battery Capacity No. 2 2.0 4.2 within the range

NAS Battery Capacity over the No. 3 2.5 3.6 range Hybrid system configuration diagram 13

 Li-ion (2,000kW) batteries are composed of 500kW unit × 5 set.  NAS (4,200kW) batteries are composed of 1,200kW unit × 2 set and 1,800kW unit 1 set.

DC/AC The PCS converts between Inverter(PCS) DC and AC as well as DC/AC protects the facilities from Inverter(PCS) possible malfunctions of the power system. AC Boost transformer DC Lithium-ion 300V batteries

Main transformer Switch gear

transmission 290V lines Breaker

NaS batteries 14

３．Balancing operation utilizing hybrid Storage Battery System Demand and supply control system 15 - ＥＭＳ(Energy Management System) Network -  EMS equipped in “Nishinoshima substation” performs centralized control through the telecommunication network. - Main function - ・Forecast of renewable generation and demand ・Charge/discharge control ・Mitigation control of short and long term fluctuation ・Diesel power generation control ：Tie line Wind power Legend ：EMS information generation ：Control system information Storage (new) Batteries Photo voltaic generation (new)

Prefectural EMS Ohmineyama (main) wind power generation Nishinoshima substation Kuroki power station EMS (terminal)

Saigo power station

Network

EMS EMS (terminal) (terminal) Control system

Power Management office Control Center EMS operation control mechanism 16

 By means of unmanned automatic operation, coordinated control between storage battery and internal-combustion power is executed. Short term control Long term control

Internal ・Weather Forecast Data combustion output Frequency ・Historical Data EMS Renewable generation Demand ⊿P+⊿f Control forecasting forecast

Feedback control

Supply and demand plan（long-term control）

The short-term control demand Supply and demand control（middle-term control）

Command the number of Economical load dispatching operating units and the output or Priority List Method Allocation of control demand

Internal Li-ion battery NAS Battery combustion 17 Operational performance of the storage battery

 Currently, coordinated control performance is generally satisfactory.

Example of Coordinated control performance (April 26, 2016)

Total demand

(MW) Total output of Internal-combustion

Lithium ion battery Total output of Renewable energy Absorb small fluctuation NAS battery output Lithium ion battery output

0 NAS battery Discharge the surplus power during the daytime to peak load

Frequency management value (upper limit) Frequency

(Hz) 60

Frequency management value (lower limit) 18

４．Effect and future prospects by the demonstration project 19 Expected benefits

①Improvement of the ②Reduction of power supply stability environmental impact Introduction of renewable By reducing fossil fuel diesel energy and storage battery power generation consumption, system improves the stability We can reduce CO2 emissions of power supply in isolated power system About 10 thousand tons CO2 reduction per year ④Development and ③Activation of the local application of new community technology

Hybrid storage battery is the Accumulate technical first challenge in Japan. knowledge such as the EMS Expect an increase of visitors control logic Contribute to the solution of global challenges

Verification being continued aiming further penetration of renewables 20 Acknowledgements

This project was realized with great support of the Ministry of the Environment, through the adoption of the “Storage battery demonstration project for promoting the introduction of renewable energy for remote islands“, subsidized by the ministry.

Also, we have received great cooperation from each municipals of Nishinoshima Town, Oki-Islands, and , in the process of the construction of the substation, and the introduction of renewable energy.

We would like to express our sincere appreciation for the efforts of those concerned. 21

(Nishinoshima) Nishinoshima Nakanoshima (Ama)

chiburijima (Chibu) Dogo (Okinoshima)

＜Demonstration project website (Oki hybrid Daisakusen )＞ http://www.energia.co.jp/okihybrid/index.html