Three-stage Evolution Mechanism of Multiple Stability Problems and Control Strategies of AC/DC Power System with Large-scale Wind Turbine Generators

There exists interactive evolution process of multiple stability problems of AC/DC power system with large-scale HVDC and wind power, such as voltage or frequency fluctuation and power oscillation, which can be caused by HVDC commutation failure. Further research is required on the evolution mechanism and control strategies of this kind of power system. In this paper, firstly three-stage evolution mechanism is proposed, including large-scale wind turbine generators tripping off caused by transient overvoltage, transient angle instability caused by power flow transferring in weak transmission section, and out-of-step separation caused by cross-regional power oscillation. Secondly, evolution processes and typical models of different stability problems are studied deeply. The prevention and control strategies are proposed. Finally, simulation results and analysis based on real-sized power grid in China prove the rationality and effectiveness of the proposed three-stage evolution mechanism and control strategies.