TOKYO – Hitachi Industrial Equipment Systems Co., Ltd. (HIES) has begun operating a next-generation power conditioner(1) called a Grid Forming Inverter (GFM), at its Narashino Works facility in Chiba Prefecture. This cutting-edge system helps stabilize electric power systems as global transition to renewable energy, by simulating the stabilizing effects once provided by large power plants.
As renewable energy becomes a bigger part of the power mix, older systems that relied on heavy rotating generators are retiring, but they also provided valuable “inertia” that kept the grid stable during power fluctuation between demand and supply. GFM technology helps recreate inertia, supporting a reliable power supply for the future.
Why This Matters
Electricity must be supplied at a stable frequency to keep our power systems running smoothly -typically at 50 Hz or 60 Hz. Traditionally, large power plants helped maintain that frequency because their heavy turbines had “inertia,” a natural resistance to sudden changes.
As more renewable energy sources like solar and wind replace thermal power plants using fossil fuels, that inertia in power system is decreasing. These newer systems can’t stabilize frequency in the same way, increasing the risk of frequency fluctuations or even blackouts.
This is where GFMs come in. They simulate this lost inertia, helping to balance the grid and maintain a stable supply of electricity – even when demand suddenly changes, or renewable output fluctuates.
About Grid Forming Inverters (GFM)
Unlike conventional inverters that simply follow the power grid, GFMs can create and stabilize their own grid, working together with other units to form self-sustaining microgrids(2). This makes them important for supporting local energy systems, improving grid resilience and enabling carbon neutrality.
Powering Narashino Works
Narashino Works now runs on a system that combines solar energy, battery storage and inverter technology to reduce CO₂ emissions and keep operations required in the emergency event– even during blackouts of utility grid.
81.9 kW of solar power (54 kW new and 27.9 kW existing) is used for the system, expected to reduce greenhouse gas emissions by 39.2 tons of CO2 annually.
A newly built AC microgrid, powered by paralleled three GFMs, keeps systems like water pumps (also made by HIES) and internal announce equipment running smoothly, even when solar power fluctuates.A DC microgrid uses solar energy more efficiently, stores surplus power in batteries and feeds it back into the plant, helping reduce conversion losses and saving energy.The system can operate independently during emergencies, strengthening Narashino Works’ disaster resilience.
Since DC power supply has an advantage in environmental performance, this system was selected for a carbon reduction subsidy from Japan’s Ministry of the Environment.(3)
(1) A device that converts DC power supplied from solar power generation systems, storage batteries, etc., into AC power that can be used in buildings, etc.
(2) A system to develop small-scale power generation facilities within a facility or region and become self-sufficient in electricity
(3) Ministry of the Environment: Selected for a subsidy for carbon dioxide emission control measures in fiscal 2024
