Identification of the frequency behaviour of a power plant during a load step in a microgrid

Abstract:
After a blackout, critical infrastructures can be resupplied by a microgrid on distribution grid level. This microgrid has to be built up from a black start capable power plant. To avoid high frequency instabilities, the microgrid has to be interconnected step by step, otherwise it might collapse again. Before each switching operation, a precheck has to be executed to ensure that the load, in this case a critical infrastructure, does not lead to uncontrollable instabilities in the microgrid. Otherwise, excessively high frequency fluctuations could lead to a collapse of the system. This paper presents an approach to anticipate the electrical frequency behaviour during a load step in a microgrid. The method is validated against different types of power plants and loads in a microgrid. The evaluated method proves to be very precise, so that the it can be utilised to determine the frequency behaviour in a microgrid.