A Smith Predictor Based High-Frequency Oscillation Suppression Method for VSC-HVDC System

This article presents a novel method to suppress high-frequency oscillations (HFOs) in voltage-source converters (VSCs) based high-voltage direct current (HVDC) systems. The analysis reveals that the main reason for HFOs is the negative damping of the VSC-HVDC impedance at high frequencies, which results from the time delay of the control system. The proposed method employs a Smith predictor to directly compensate for the time delay of the VSC-HVDC control system and eliminate the HFOs. The article first reviews the instability mechanism of VSC-HVDC systems. Then, it presents the Smith-predictor-based control method for HFO suppression and evaluates its robustness. Finally, the proposed method and theoretical analysis are verified by simulation and hardware-in-the-loop tests results.