Frequency Support of an Energy Storage Doubly-fed Condenser Based on Sliding Mode Control

As a new type of synchronous condenser equipment, the energy storage doubly-fed condenser (ESDFC) not only possesses strong voltage support capability of synchronous condenser, but also fully leverages rotor energy storage to improve system frequency response characteristics, thereby meeting system requirements for high-inertia support and frequency. To address the issue of slow dynamic response speed of ESDFC under vector control and the large initial frequency change rate under load disturbances, a sliding-mode control strategy based on super-twisting reaching rate is proposed. The active reference value is incorporated with virtual inertia control in the strategy, enabling the ESDFC to provide frequency support for power system more efficiently under large load disturbances. A new-energy station model incorporating ESDFC is built in MATLAB/Simulink to validate the effectiveness of the proposed control method. Simulation results demonstrate that the proposed control method can effectively suppress the chattering phenomenon of traditional sliding mode control in the steady-state power tracking process, significantly improve the dynamic response speed and frequency support capability of the ESDFC under different load disturbance conditions, and reduce the frequency change rate of the system.