A 21 MW Energy Storage System as an Instantaneous Reserve Source. Test Results in Föhren

The German operator Westnetz announced the success of the first test within the “SUREVIVE” project. A large-scale energy storage system with a capacity of 21 MW proved that it can take over the role of conventional power plants in maintaining grid frequency and voltage stability using grid-forming technology. Until now, grid stability relied on so-called inertia generated by the rotating masses of large turbines in coal or gas power plants. As decarbonization progresses, demand is growing for digital equivalents of this function. The test carried out in Föhren shows that energy storage systems are ready to fill this gap.

A grid-forming storage system

The heart of the installation, with parameters of 21 MW / 55 MWh, is an innovative inverter control technology. The system uses grid-forming solutions from SMA, enabling the storage system not only to respond to grid parameters, but to actively shape them.

“The first test was successful. We demonstrated that the installation in the medium-voltage grid reacts in grid-forming mode exactly as we calculated and expected,” comments Ingo Liere‑Netheler, project manager at Westnetz.

The key conclusion from the test is that the storage system was able to provide a system service equivalent to the inertia of conventional generation units. This means it can instantaneously compensate for short-term frequency fluctuations.

Partnerships and technology

The “SUREVIVE” project, developed under the leadership of Schoenergie, integrates technologies from leading suppliers:

Battery system – supplied by Hithium
Charging – the storage system operates in conjunction with a dedicated photovoltaic installation
Research – scientific supervision is provided by the Fraunhofer Institute for Solar Energy Systems (ISE)

“The field test shows that system-stabilizing functions can be assessed not only in simulations and laboratories, but also under real grid conditions,” emphasizes Roland Singer from Fraunhofer ISE.

Implications for the market

Westnetz’s success is a signal to distribution system operators across Europe. Until now, energy storage was mainly associated with price arbitrage or alleviating grid congestion. The “SUREVIVE” project demonstrates that storage systems can play a far more critical role—as guardians of the grid’s physical parameters.

In the next stages of the project, researchers will analyze various test scenarios in order to develop standards for large-scale deployment of grid-forming technology. This is a necessary step to safely phase out further conventional generation units without risking system destabilization.