(1. State Key Laboratory of Power Transmission Equipment & System Security and New Technology(Chongqing University), Chongqing 400044, China; 2. Dongfang Electric Machinery Co. Ltd., Deyang 618000, China)

Aiming at enhancing the capability of the network frequency modulation supported by the doubly fed pumped storage unit(DFPSU), a kind of improved proportional-differential(PD)loop virtual inertia control strategy of DFPSU is proposed. First, based on the operation characteristics of DFPSU, the models of reversible pump turbine, doubly fed induction machine and control system of DFPSU are established. Then, according to the relationship between the virtual inertia, the rotational speed adjustment and the network frequency variation, a kind of improved PD loop virtual inertial control strategy of DFPSU is proposed. In addition, a control parameter calculating method in the improved PD virtual inertia control is also provided. Finally, a three-machine system with DFPSU is used to validate the proposed control strategy. The simulation results show that the proposed control strategy could effectively improve the frequency response ability of DFPSU in both the generator and motor mode and the frequency stability of the power system at the same time. This work is supported by National Natural Science Foundation of China(No. 51377184)and Fundamental Research Funds for the Central Universities(No. 106112016CDJZR158802).