The nowadays control in the European interconnected grid is based on the physical properties of the synchronous generators in large-scale conventional power plants. With their rotating masses, these generators provide the necessary electrical stability for the power supply. Therefore, a sufficiently high proportion of these so-called »must-run units« must be connected to the grid at any time to ensure a stable system operation. In an energy system based on 100 % renewable energy, power converters must assume all necessary system services, for example, in photovoltaic and wind power plants or in large-scale battery storage systems.
Various types of power plants connected by power electronics, such as PV plants, wind turbines, battery storage systems, but also HVDC converters, STATCOMs and electrolyzers, are suitable for grid-forming. However, since these converter-based plants, in contrast to electro-mechanical synchronous generators, do not inherently possess the corresponding electrical behavior, suitable new control structures must be developed, implemented, and tested. This is the only way to ensure stable grid operation at any time in the future, without large synchronous generators. For this purpose, we are developing novel grid-forming control methods for power converters, which can provide the grid with all system services and stabilize it not only during normal operation but also during major disturbances.
Furthermore, the structure of the power grid will change fundamentally due to the decentralized installation of renewable generators. Therefore, we develop methods for the control and stability analysis of such decentralized converter-based grids of the future. In doing so, we investigate interactions between different power converters as well as between power converters and other grid components.
The verification of these new system services and behaviors is central to a stable, reliable, and resilient grid operation. We develop methods for the verification of the grid-forming behavior of power converters as well as new grid control methods. Furthermore, we test the new behavior and grid services as well as the verification methods at the Multi-Megawatt Lab.