Research on frequency simulation model and control strategy of hydropower islands

When send end hydropower islands isolated from interconnected grid in large disturbance, frequency of the island will fluctuate markedly. Regular prime mover and governor transient models are not accurate enough in simulating the frequency performance. In this paper, considering the nonlinear character of hydraulic turbine and the influence of no-load gate opening, hydraulic turbine and governor models feasible for long term frequency simulation involving large variation are established. The feasibility and accuracy of the models are verified by the load rejection test data of hydropower plant in Sichuan. Further simulations and analyses of hydropower islands with the above models are performed. For the over frequency problem of the islands, generator tripping scheme and its evaluated index are proposed which will be updated along with the changing of system operation points. The advantages of proposed methods are proved by simulations on hydropower islands in Sichuan.