Frequency stability analysis for inverter dominated grids during system split

In the past few years, the electrical power system in Continental Europe has gone through a radical change with a subsequent increase in the share of inverter based generation. The increase of inverter based generation in the power system and the planned disconnection of conventional power plants are raising a crucial challenge due to the reduction of power system inertia. From past studies, it has been observed that the CE system has shown acceptable frequency behavior even with a significant reduction in power system inertia. However, in the case of a system split, the resulting power imbalance together with low inertia could lead to power system instability. The main focus of this paper is to analyze frequency stability during system split situation within an exemplary test system with the help of two modeling approaches: firstly, with a load frequency control model and secondly, with a more detailed dynamic grid model. An extended load frequency control model has been further developed considering load shedding, limited frequency sensitive mode of inverter based generation and contribution of inverters to power system inertia. The results obtained from the different modeling approaches are compared. Finally, advantages and limitations from both investigation approaches are discussed.