Optimizing Method for Key Parameters of Under-frequency Load Shedding for Power System Penetrated with Hydropower

Under-frequency load shedding is an important part of the last defense line for power grid. However, the under-frequency load shedding device is prone to overcutting when large power shortage disturbance occurs in the grid system with high penetration of hydropower. Based on an analysis of the frequency variation characteristics following power shortage fault of power system penetrated with hydropower, an optimization method is proposed with appropriate step size for the key parameters of under-frequency load shedding, according to the water hammer effect principle and with consideration of the frequency characteristics of the power grid after disturbance and the water hammer effect. The simulation test has proved that the method can be effectively applied to the power grid with high penetration of hydropower to reduce the overcutting problem following the extreme power shortage disturbance.