High-Frequency Resonance Suppression of MMC-HVDC Based on the Coordination of Voltage Feedforward Filtering and Passive Damping

The interaction between the negative damping inductive characteristics of MMC-based converter station in the high-frequency band and the capacitive characteristics of the AC system is the reason for the high-frequency resonances (HFRs). Existing damping controls and voltage feedforward filtering methods cannot suppress the HFRs completely because the negative damping of MMC in the high frequency range cannot be eliminated, resulting in the persistent HFR risk. To address this problem, the requirements of voltage feedforward loop for shifting the mentioned negative damping frequency range is revealed based on the simplified MMC impedance. A voltage feedforward filter composed of a notch filter and a first-order low-pass filter is presented accompanied by the parameters calculated and optimized. Furthermore, a coordinated suppression strategy integrating voltage feedforward filtering with a passive damping filter is proposed based on the principle of impedance reshaping. This strategy can eliminate the negative damping of the HVDC station completely in the high-frequency range while simultaneously reducing the parameters of passive damping filter. By doing so, the comprehensive performance of the coordinated suppression scheme is significantly improved. Time-domain simulations validate the effectiveness and robustness of the proposed method under various operating conditions.