Fraunhofer ISE Testlab sets standard for inverters
Stable system operation is essential for the success of the energy transition. In the future, renewable power sources and storage systems will have to take on grid-forming properties. Fraunhofer ISE's new test procedure provides clarity in the market and accelerates the development of tried-and-tested devices and standards.
With the increasing expansion of renewable energies, the rotating masses of conventional power plants, which previously ensured a stable voltage and frequency, are no longer present in the grid. Grid-forming inverters must take over this task and reliably stabilize the grid even in critical situations such as frequency changes or short circuits. Until now, however, there has been a lack of a uniform definition and standardized verification procedures for these systems.
GFM Benchmark test procedure
In the GFM Benchmark project, Fraunhofer ISE invited leading manufacturers to test their devices in the laboratory. Seven companies provided inverters with different outputs and development statuses. The test procedure was developed together with German transmission grid operators and simulates various grid situations. In addition to normal operation, it also includes extreme situations such as phase jumps and short circuits in the grid.
While many devices react similarly under clearly defined requirements, there are still clear differences under more complex conditions. The ISE team was therefore able to provide manufacturers with valuable tips for optimization and highlighted the need for further development.
Paving the way for standardization and market integration
The project results have been directly incorporated into European standardization work and the VDE FNN note “Grid-forming properties”. For the first time, the new test guideline provides a recognized framework for the practical testing and certification of grid-forming systems. This is particularly relevant as a new market for instantaneous reserve will be launched in Germany from 2026, in which battery storage systems with suitable certification, for example, will receive additional revenue opportunities.
Market maturity, best practice and industry dialog
The market analysis and test data provide a solid basis for decision-making for manufacturers, grid operators, investors and standards bodies. The certification measurements that are now possible will accelerate the market entry of new, stabilizing inverters. In addition, Fraunhofer ISE supports the transfer of European requirements into national regulations and supports the industry with best practice guidelines.
Fraunhofer ISE has set a milestone with the test procedure for grid-forming inverters. This will not only make the energy transition in Europe safer, but also measurably faster.