Coordinated Control of Guide Vane Opening and Rotor Speed in Variable Speed Pumped Storage for Grid Frequency Support

This paper proposes a new control method in variable speed pumped storage (VSPS) for grid frequency support, which integrates the complementary characteristics of guide vane opening (GVO) and rotor speed in frequency response (FR) with respect to the speed and range. First, the detailed operation principle of water energy conversion in VSPS is analyzed. Subsequently, auxiliary variables are introduced to achieve decoupling control of hydraulic and electrical subsystems. Furthermore, a second-order sliding mode controller is developed to improve the GVO regulation speed. On this basis, a coordinated control strategy of GVO and rotor speed for frequency support is designed. Specifically, the activation of GVO control occurs only when the FR power demand observed by the centralized disturbance observer exceeds the existing rotor kinetic energy. So as to achieve that small and high-frequency power disturbances are absorbed by rotor speed adjustments. Besides, the Lyapunov method is employed to show the convergence and stability of the proposed method. Finally, hardware-in-the-loop test results are presented to verify the effectiveness of the proposed control strategy in improving the system's stability, increasing the VSPS's frequency support capability, and alleviating frequent surge impacts caused by the frequent regulation of guide vanes.