1 The Standardization of Distribution Grid Communication Networks Zhao Li, Member IEEE, Fang Yang, Member IEEE, Dmitry Ishchenko, Member IEEE meters, sensors, and intelligent electronic device (IED)) and Abstract--This paper reviews the recent development in the system control through sending control commands to distribution utility communication networks including the controllable equipment. As transported messages carry advanced metering infrastructure (AMI) and the supervisory information of system status and/or control that are important control and data acquisition (SCADA) system. The to maintain the normal operation of the system, particularly standardizations of application level communication protocols in when the grid is hit by a large disturbance, the communication both AMI and SCADA systems are the major focus of this paper. network should ensure the instantaneous deliverability of In addition, some smart grid applications facilitated by the advances in the distribution communication networks are also important messages. If a control center fails to deliver or discussed. allows the delay of delivering such a message, it may lose the opportunity to govern a disturbance and potentially render the Index Terms-- Smart Grid, AMI, SCADA, Communication grid system unstable and unreliable. Hence, building a large Protocol. scale real-time communication network becomes one of important pre-requests for Smart Grid [4]. I. INTRODUCTION Nowadays, distribution utilities mainly adopt two types of communication networks: the supervisory control and data Promising solution for challenges presented by the acquisition (SCADA) system [5], [6] and the advanced globally rising energy demand, aging power system A metering infrastructure (AMI) [7]. In the past several decades, infrastructures, increasing fuel costs, and emerging renewable SCADA has played a key role in the online monitoring and resource portfolios is the smart grid [1]. Technically, smart control of the grid system. However, constrained by high costs grid applies the advanced monitoring and control technologies on constructing a real time communication system, SCADA to the electric grid, which enables sustainable options to has been mainly deployed in transmission system and a small customers and improves security, reliability, and efficiency for part of distribution system (e.g., distribution substations) for utility grid operation [2], [3]. real-time monitoring and control. In contrast, because of Since one primary goal of the smart grid is to improve relatively low cost on building a non-real-time communication energy efficiency, it is often referred to as the “green grid”. system and the stimulus from US government, AMI has been Two green features of the smart grid are that it maximizes the widely deployed in the distribution system recently, reaching utilization of renewable resources (e.g., solar and wind) and the feeder and residential levels. Rather than functioning as a improves the efficiency of system operation through loss monitoring and control network, AMI implements an reduction, dynamic pricing, and other applications. On the infrastructure to automatically collect energy usages from other hand, different from a traditional system in which power residential smart meters and transports them back to the generation and consumption can be well planned and control center on a monthly basis. It improves the efficiency estimated, in smart grid, the power generation and of the process of collecting residential energy usages and the consumption become more dynamic and unpredictable due to quality of collected measurements, and eventually enhances the intermittence of renewable resources and dynamic price the quality of customer service. driven power consumption. The unpredictable power In the past several years, efforts have been invested into building the large scale smart grid communication networks production and consumption complicates the grid reaching the feeder level or the residential level. These efforts management. To efficiently manage a grid system with these include extending the scope of SCADA and/or enhancing the dynamic features, utility control centers should be able to real-time capability of AMI. With the scope of the monitored monitor and control the grid in real-time. network reaching the feeder and residential level, the number Utility control centers implement system monitoring by of monitored data points is significantly increased, reaching collecting measurements from field devices (e.g., smart millions. Hence, improving efficiency and quality of the smart grid communication network and increasing interoperability Financial support from the ABB Corp. Research Center is gratefully between devices produced by various vendors become acknowledged. The authors appreciate the discussions and help from important topics and lead to the standardization of the colleagues Zhenyuan Wang and Xiaoming Feng. The authors are with the ABB US Corp. Research Center communication protocols and information models. 940 Main Campus Dr. Suite 200, Raleigh NC, 27606, United States This paper primarily reviews the efforts on standardization Email: {zhao.li, fang.yang, Dmitry.ishchenko} @us.abb.com of application level communication protocols in both SCADA 978-1-4673-2729-9/12/$31.00 ©2012 IEEE 2 [9] and AMI [10] recently. The rest of this paper is structured support new requirements (i.e., demands responses) from the as follows: focusing on AMI infrastructure, the second section smart grid [11]. first introduces its components, and then discusses the The standardization of the AMI infrastructure includes the standardization of the AMI protocols. Similarly, the third standardization of both AMI communication protocols and section discusses SCADA and recent standardization efforts. AMI information models. Section four discusses some potential advanced smart grid Table 1 Communication modules supported by AMI vendors applications triggered by real-time and/or near real-time smart-grid communication networks. Section five concludes AMI Vendors Communication Modules this paper. Landis + Gyr Unlicensed RF, PLC Zigbee, unlicensed RF, Public Itron II. ADVANCED METERING INFRASTRUCTURE carrier network (OpenWay) Unlicensed RF, public carrier Elster network A. Background Echelon PLC, RF, Ethernet AMI consists of metering, communication, and data GE PLC, public carrier network, RF management functions, offering the two-way transportation of Sensus Licensed RF (FlexNet) customer energy usage data and meter control signals between Eka Unlicensed RF (EkaNet) customers and utility control centers. The AMI was originally developed from advanced meter reading (AMR) [12], [13], SmartSynch Public carrier network [14], [15], and [16], a one-way communication infrastructure Tantalus RF(TUNet) that implements automatic collection of meter measurements Triiliant ZigBee, public wireless network from residential smart meters to utility control centers for calculating monthly bills and fulfilling other related activities. Partially as the next generation of “AMR”, AMI not only The Standardization of AMI Communication Protocols enhances the traditional data collection functionality (i.e., In the past two years, the focus of the standardization of improving monthly meter data collection to real time or near AMI communication protocols has gradually shifted from the real-time meter data collection) but also develops the remote physical level (e.g., ANSI C12.18 [18]) and the device level control capability from the control center to smart meters. (e.g., ANSI C12.21 [20]) to the application level (e.g., ANSI Motivated by the economic stimulus plan of the U.S. C12.22 [21]) because application level communication government, most U.S. states have begun the process of protocols effectively isolate the details of underlying physical deploying smart meters within AMI infrastructures. At the network configurations and implementation. This section beginning of 2009, for example, Texas initiated a project of introduces two application level communication protocols that deploying six million smart meters and expected to complete are popular in both the United States (i.e., C12.19 and C12.22) it by 2012; and California plans to install 10 million smart and European markets (i.e., IEC 62056-53 and IEC 62056- meters by the end of 2012. The deployment of smart meters is 62). taking place not only in the United States but throughout the world. Based on current estimates, by 2015, smart meter ANSI C12.22 installations are expected to reach 250 million worldwide [17]. Hence, for most utilities, AMI will be a well-deployed Historically, after a set of standard table contents and feeder or residential level communication network, delivering formats were defined in ANSI C12.19, a point-to-point a large amount of data in real time or near real time (e.g., standard protocol (ANSI C12.18) that transported the table every 15 minutes). data over an optical connection was developed. Afterwards, the “Protocol Specification for Telephone Modem B. The Standardization of the AMI Infrastructure Communication” (ANSI C12.21), which allowed devices to transport tables over telephone modems was defined. The In the current market, smart meters from different vendors C12.22 standard, expanding on the concepts of both the ANSI are using proprietary communication protocols that are C12.18, and C12.21 standards, allows the transport of table generally non-interoperable (Table 1). For utilities, deploying data over any reliable