2022年4月6日

　The New Energy and Industrial Technology Development Organization (“NEDO”) and Sumitomo Electric Industries, Ltd. (“Sumitomo Electric”) have completed a demonstration project in the U.S. State of California to improve the power quality of the grid, and have successfully achieved the major deliverables such as establishment of a microgrid on a commercial power distribution network inclusive of 66 customers, operation of a large-scale stationary storage battery, the Redox Flow Battery (RF Battery), and multi-use operation in both normal and emergency situations.

　The system makes it possible to earn revenue through electricity market transactions during normal operations, in addition to providing power to blackout areas or the areas that outages are assumed, as an independent power source, during an emergency such as natural disasters and planned outages. It is the first time in the U.S. and Japan that a microgrid has been operated on a commercial distribution network with the storage batteries as the main power source, bracing for a power outage.

　The results of this demonstration project could be applicable to the cases with high potential demand both in Japan and abroad in the future, such as microgrids with solar and wind power facilities constructed for off-grid areas and 100% renewable energy supply is required for the islands where the transportation cost of power generator fuels is expensive.

1．概述
　The U.S. state of California has enacted Senate Bill 100, aiming to use only clean greenhouse gas-free energy sources by 2045, and is promoting the introduction of energy storage facilities as a solution to the problem of deteriorating electricity quality due to the mass introduction of renewable energy. In addition, California has been increasingly experiencing emergency planned and rotating power outages recently as a countermeasure to wildfires and rapid increase of air conditioning load during extremely hot weather, which is becoming a social issue. Thus, in the event of a power outage, the consumers like data centers supply electric power from storage batteries only to the circuits connected to specific distribution boards (critical load distribution boards) as power outage countermeasures. But countermeasures against power outages to cover wider areas and strengthening the power system resilience are also requested.
　With this background, NEDO commissioned Sumitomo Electric in September 2015 and proceeded with the demonstration project^＊1在圣地亚哥，利用氧化还原液流电池(射频电池)^＊2，属于固定式蓄电池，使用寿命长，适合大规模使用。
　RF batteries have an advantage in that they do not experience degradation due to factors like charging/discharging nor by the number of cycles and makes it easier to measure the remaining energy in batteries in real time. The project has been developing bidding strategies and conducted a demonstration which could increase profits in both the energy market (electricity trading market) and the ancillary services^＊3市场，还使选择高度灵活的电力交易招标模式成为可能，该模式已于2018年12月与当地电网运营商(独立系统运营商)启动^＊4。
　In 2021, NEDO and Sumitomo Electric decided to additionally demonstrate the operation^＊5在配电网上的微电网，利用射频电池设施作为对抗计划和旋转停电的对策，这正在成为国家的一个问题，并于10月开始成功运行。在美国和日本，以蓄电池为主要电源的商业配电网运行微电网，以应对停电情况尚属首次^＊6。
　NEDO and Sumitomo joined GO-Biz and SDG&E to issue an additional joint press release which can be accessed at :<https://www.sdgenews.com/article/sdge-and-sumitomo-electric-complete-zero-emissions-microgrid-pilot-project-helping-advance>

2．我们的成就
　(1) Enhancement of grid resiliency by microgrid operation with VRF battery has been validated Microgrid with VRF battery (8MWh) has successfully provided electricity to 66 real residential customers, as stand-alone power source, through distribution network on the assumption that they are disconnected from the grid during power outages because of natural disasters etc.
　Although both electricity demand and power output of solar systems in the microgrid are always fluctuating, the VRF battery could stabilize the voltage and frequency of the distribution lines by charging/discharging the power required to sustain supply-demand balance.
　We have confirmed that it is possible to stably shift from a grid-connected state to a microgrid^＊7无论是黑启动过渡，即在停电期间启动蓄电池，还是无缝过渡，即用户不会注意到停电。
　The above-mentioned demonstration results validated that we could supply power to　 foreseeable blackout areas as a stand-alone power source within a microgrid in times of an emergency such as planned outages and natural disasters, while earning profits through power transactions with a grid operator during normal times.

　(2) Performance of the VRF battery through the demonstration project has been validated The results of the performance validation through the demonstration project are as follows:
　●　We verified that the profitability in electricity market transactions could be improved by applying the highly flexible bidding algorithm as well as by taking advantage of the feature of RF battery that neither of the charge/discharge pattern, the number of cycles, nor the operational range of SOC (State of Charge) could become the factor to accelerate battery degradation.
　●　The decrease in the energy capacity of RF battery in about four years’ time is very small, even when the battery is charged and discharged in the range from SOC 0% to 100% continuously with steep power changes in such an operation like the California Independent System Operator (CAISO). The expected capacity even after 20 years, based on the demonstration results, indicates it is expected to keep the rated energy capacity (8MWh).
　●　We have verified not only the absence of significant battery degradation, but also the high reliability of the system. During the four years of demonstration operations, there were no major system failures and the high availability rate (99%)^＊8系统被确认。

　The results of this demonstration project could be applicable to the cases with high potential demand both in Japan and abroad in the future, like when microgrids with solar and wind power facilities are constructed for off-grid areas or 100% renewable energy supply is required for the islands as the transportation cost of power generator fuels is expensive.
　By disseminating the technology developed in the project, NEDO and Sumitomo Electric will contribute to enhancements of grid resiliency, and realizing the carbon neutral society by both increasing the renewable energy and decreasing greenhouse gas emission.

(笔记)
* 1项目
　 Project title: International Demonstration Project to Prove Japanese Technology for Improved Energy Consumption Efficiency/Demonstration Project Testing Storage Battery Operation for Both Electricity Transmission and Distribution in California, USA
　 Project period: FY2015 to FY2021
　Link:https://www.nedo.go.jp/english/news/AA5en_100015.html

*2氧化还原液流电池(RF电池)
　A RF battery system consists of cells for battery reaction, tanks for storing active material, pumps, and pipes for circulating the active material. In RF Battery, the output (kW) and capacity (kWh) parts are independent of each other, allowing for appropriate output power and energy capacity design according to application.
　The charging and discharging reaction cause a change only in the valence of the ions in electrolytes, which prevents degradation of the electrodes and the active material, making it suitable as a long-life large storage battery. In addition, because it can operate under normal temperatures and is composed of non-combustible or flame-retardant materials, the possibility of a fire with the batteries is extremely low.
　 As the state of charge is monitored accurately, the batteries ensure maximum safety in system operations.

*3辅助服务
　 Technical and operational schemes to maintain power quality. They include power balance monitoring, operating grids, and voltage/frequency regulation. In the past, utility companies were in charge of ancillary services. But in recent years, some functions of ancillary services have been identified, monetized, and built into the markets.

*4已于2018年12月与当地电网运营商(独立系统运营商)启动
　 Reference：NEDO news release, December 18, 2018 “Initiating Redox Flow Batteries into the U.S. Wholesale Power Market―Demonstrating the economic potential of storage batteries―”
　 Link:https://www.nedo.go.jp/english/news/AA5en_100399.html

*5决定额外核查该行动
　 Reference: NEDO news release, January 22, 2021 " NEDO Extends Redox Flow Battery System Project to Conduct an Additional Demonstration of a Microgrid as a Solution to Power Outages in California”
　 Link:https://www.nedo.go.jp/english/news/AA5en_100433.html

*6这是美国和日本首次在商业配电网络上运行以蓄电池为主要电源的微电网，为停电做好准备
　 Researched by Sumitomo Electric

*7稳定地从并网状态转变为微电网
　 As an example of microgrid operation, the waveforms of the microgrid frequency and the output of the storage batteries (following the load) during microgrid operation with black start (starting the microgrid from a power outage, disconnected from the grid) are shown below. It was confirmed that the RF battery became a stand-alone power source and maintained a stable frequency by balancing supply and demand of the load in the microgrid.

*8可用率
　 Operating rate during the CAISO operational trial period, excluding periods of the outages due to the problems other than the battery equipment.