Generators, storage facilities and loads are increasingly being connected to the grid via inverters. Power electronic devices will thus become the key component in future power grids. As a result, the transformation of the energy system is characterized by the transformation from an electromechanical to a power electronics based electrical energy system.
In today's power supply system, inverters are not only feeding power into the grid or are using the power from the grid. Modern inverters in photovoltaic, wind energy or storage systems can provide important system services. This includes, for example, the provision of reactive power for local voltage regulation or the contribution to frequency maintenance by throttling or increasing the active power supplied. In addition, converter-based generation plants participate in the dynamic grid support in the event of a fault through active fault current feed-in, for example through the so-called fault ride through capability (FRT).
As the energy revolution progresses, conventional power plants are increasingly being pushed out of the grid. Fraunhofer ISE is working on control engineering processes to keep the power grid stable even if there is little or no feed-in from conventional power plants. This concerns for example the voltage and frequency formation (grid-forming), as well as the provision of instantaneous reserve or control energy from battery storage. Using the example of so-called microgrids, new processes are being tested in reality.
Fraunhofer ISE is developing new analytical methods for the assessment of interactions between power electronic devices and the power grid, which enable targeted damping of resonance and harmonic effects. The temporal and spatial changes in the energy flows in the network pose new challenges that require new modelling strategies and corresponding dynamic network simulation methods. Fraunhofer ISE is investigating how the contribution of renewable power plants to grid stability can be optimized by making the best possible use of the flexibility of power electronic components.
With these activities, Fraunhofer ISE is making an important contribution to clarifying the question of how electricity from renewable sources can be optimally fed into the power grid and how grid stability can be guaranteed and even improved.