Perturbation Observer-Based Frequency Support Control Strategy of VSC- HVDC System

Aiming at the problem that the voltage source converter based high voltage direct current (VSC- HVDC) transmission system cannot respond to frequency change of the receiving-end AC grid under traditional control strategy, this paper proposes a perturbation observer-based frequency support control strategy (POFSCS) to improve the active and rapid support capability of the VSC-HVDC system for grid frequency regulation. Firstly, a two-region VSC-HVDC system model is constructed. Then, the frequency-supported control strategy is designed using perturbation observer and feedback linearization control method. The strategy utilizes the maximum available energy of the DC capacitor to regulate grid frequency deviation, thereby improving the response speed and output depth of the frequency regulation controller. Finally, the effectiveness of POF-SCS is verified in MATLAB/Simulink platform. The simulation results demonstrate the effectiveness of POFSCS in effectively suppressing significant frequency deviations and contributing to the enhancement of frequency stability in the receiving-end grid.