Study of Frequency Stability Control Strategy for Islanding VSC-HVDC Power System

The HVDC power transmission system will fall into islanding operation mode under fault conditions, bringing sever frequency stability problems to the islanding system. The regulation performance of the DC system and the generators both affect the frequency stability of the islanding system. This paper proposes a coordinated frequency control strategy, combining the regulation performance of both the flexible DC system and the generators, for the islanding VSC-HVDC power system. Taking advantage of the fast modulation characteristics of the DC system, DC power support strategy is put forward, with the impact of control parameters as well as the DC power level and generating schemes in consideration. Besides, Governor Power System Stabilizer (GPSS) is designed, and the PSS parameters are optimized, together forming the joint control strategy. The simulation results verify the effectiveness of the proposed control strategy, which may provide valuable reference for islanding system operation.