The global energy sector is currently experiencing significant changes, with the power grid being a critical component of this transition. Japan’s approach to building a smart grid system is based on the Power Sector Reform initiated by the Ministry of Economy, Trade, and Industry (METI) following the 2011 earthquake in Eastern Japan. The reform aimed to establish a more stable electricity supply system, reduce costs, and make more rational choices for retail electricity providers.
The Japanese electricity sector is also undergoing significant changes due to low demand growth, increasing installed capacity of renewable energy sources (RES), and the development of the Reform. The integration of RES into the electricity grid is currently reducing energy prices in the wholesale electricity market, capacity factors of power plants, and their revenues due to marginal cost approaching zero. This has led to a decrease in predictability of cost recovery and a decline in investments in power plant construction by generation companies.
To encourage investment in electricity generation and ensure predictability and efficiency of reserves/capacity in the short and long term, a market mechanism for fair compensation of electricity sources has been established, segmented into kWh, kW, ΔkW, and environmental values. Negawatt trading (DR: Demand Response) is promoted from the perspective of ΔkW value, which is beneficial for diversifying energy sources and ensuring capacity/reserve security.
Japan’s goal of 53 GW of PV capacity ensures approximately 33% of the peak demand, but there are critical issues such as fluctuating frequency, excess power generation, inadequate transmission capacity, and insufficient rotational inertia in the transmission network. To address these issues and increase the installation capacity of RES, various coping measures have been explored, including the efficient use of Battery Energy Storage Systems (BESS), electric vehicles (EVs), and Heat Pump Water Heaters (HPWH).
In recent years, Japan’s electricity system has been repeatedly disrupted due to natural disasters such as earthquakes, typhoons, and heavy rainfall. To recover from large-scale natural disasters, it is necessary to establish an electricity system capable of recovering through technical measures, continuous operational support, and business management.
Japan’s “3E + S” plan aims to achieve non-intermittent, smart, and flexible electricity systems with significant integration of renewable energy to meet the “3E + S” criteria.
Japan’s smart grid implementation progress has been significant, with the Institute of Electrical Engineers of Japan (IEE) stating that a smart grid is an electricity system that integrates control technologies, information exchange, distributed computing, sensors, and transmission equipment to achieve sustainable efficiency, economically viable electricity supply, and safety through the integration of renewable energy sources (RES). To avoid PV curtailment, a feasible solution is to efficiently use controllable devices on the demand side to balance supply and demand.
Several national projects related to smart grids have received government support since 2010. Notable projects include the R&D Project for Optimal Control of the Next-Generation Distribution and Transmission Grid, which focused on demonstrating next-generation control of the transmission and distribution grid, emphasizing a new control method for demand-responsive devices to balance supply and demand. The project involved major utilities, large manufacturers, and universities in Japan over a span of six years.
The demonstration project on Nii-Jima Island, which has a renewable energy generation capacity of approximately 1,000 kW, has been conducting on-site testing of distribution and coordination Energy Management Systems (EMS) since 2014. The decentralized and coordinated EMS, including a regional central control system operated by the network operator and an integrated distributed energy source control system, work in conjunction with the current demand forecasting system and control system for diesel engine generators.
This project on Nii-Jima Island demonstrates advanced technologies to mitigate the variability of renewable energy sources and optimize their integration into the grid while ensuring a reliable and cost-effective power supply.
In conclusion, Japan’s commitment to advancing smart grid technology and optimizing the integration of renewable energy sources into the grid has led to significant progress in the implementation of smart grids. By incorporating renewable energy sources into the grid, Japan can ensure a reliable and cost-effective power supply while mitigating the variability of renewable energy sources.
The Virtual Power Plant (VPP) is a system that manages supply-demand combinations through IoT integration, enabling customers to balance and control their devices. This integrated system functions like a power plant, providing balancing capabilities such as Replacement Reserve (RR) and RR for Feed-in Tariff (RR-FIT). If the VPP response rate is fast, it corresponds to Frequency Containment Reserve (FCR), Synchronized Frequency Containment Reserve (S-FRR), and Frequency Restoration Reserve (FRR).
Japan’s power system has faced disruptions due to natural disasters and the massive integration of Renewable Energy Sources (RES) from an operational perspective. To ensure the resilience of the power system, Japan has been researching and developing concepts such as Virtual Power Plants (VPPs), Smart Grids, and Super Microgrids. A Super Microgrid is defined as a group of interconnected loads and Distributed Energy Resources (DERs) within clearly defined electrical boundaries, operating as a controllable entity.
In Japan, the fundamental concept of a Super Microgrid is similar to that in the United States, with the additional notion that it should not adversely affect the main grid’s operations, such as frequency control under normal conditions. Super Microgrids have gained attention for their ability to maintain business continuity and enhance resilience during natural disasters, although they come with higher costs compared to conventional grids.
Some notable Super Microgrid projects in Japan include the Hachinohe City project, which includes biomass cogeneration, batteries, Photovoltaics (PV), small wind power generation, and loads from the Hachinohe City Hall and some schools. This project is connected to the Tohoku EPCO grid at two common connection points and has successfully islanded operation using actual loads during emergency states and economically interconnected operation with minimal CO2 emissions under normal conditions.
The Tohoku Fukushi University Super Microgrid project in Sendai City, also supported by NEDO, features six levels of power quality: Normal, High A, B1, B2, B3, and DC supplied on different circuits. The system also includes Molten Carbonate Fuel Cells (MCFC) and PV to provide backup power in addition to gas engine generators.
Despite some upgrades, the Super Microgrid continues to operate, providing electricity and heat to Tohoku Fukushi University for two days during a power outage in 2011.
Source: Khac Nam – Specialist of Energy Vietnam Magazine