Analysis of power system frequency responses with hydro turbines incorporating load shedding

As shown in many recent works, the load-frequency behavior can be represented by system frequency response models especially for an islanding process. In this paper, a frequency response model incorporating an under-frequency load-shedding scheme is presented for islanding power system simulations. The model was applied for a practical power system with both hydro and fossil-fired power generators. The governing system models are involved in the model, which have great impact on the system dynamics. Parameter identification method is used to find and verify the model parameters. Similar responses were observed between the simulations and the accident records. The simulation results showed disadvantages of the primary frequency control systems of hydro power generators at the beginning of the load disturbances. An closed fossil fired power plant is proposed to serve against the load disturbances and improved stability was observed according to the system simulation results.