Coordinated Control of Doubly Fed Variable Speed Pumped Storage and Flywheel Energy Storage Participating in Frequency Regulation

The combination of doubly fed variable speed pumped storage (DFVSPS) and flywheel energy storage (FES) can make full use of different technical advantages of different types of energy storage, and participate in frequency regulation in the whole stage of grid frequency fluctuation. Based on the frequency fluctuation characteristic of power grid, a coordinated control method of DFVSPS and FES participating in frequency regulation is proposed in this paper. With the FES adopting virtual inertia control and droop control, and the DFVSPS adopting droop control, the frequency fluctuation is suppressed during the inertial response period. Moreover, by reducing the power of the FES, and increasing the power of the DFVSPS to compensate the reduced output of the FES, the energy storage system can provide persistent energy to support the power grid during the frequency recovery period and improve the ability of the FES continuously participating in frequency regulation. Simulations are performed to verify the effectiveness of the proposed method.