MMC-HVDC System High Frequency Resonance Suppression Method Based on Capacitive Filter

The impedance characteristics of the MMC HVDC converter and the connected AC line are analyzed. The impedance amplitude-frequency and phase-frequency characteristics of the converter and the AC power grid are obtained by impedance frequency scanning method. Then the mathematical expression of the impedance is obtained by mathematical fitting method. The Nyquist stability criterion is applied to the stability analysis of the high frequency resonance generated by the MMC HVDC connected into the power grid. On this basis, a MMC HVDC high-frequency resonance suppression method based on capacitor filtering is proposed. Taking Chongqing and Hubei back-to-back MMC HVDC inter connection network project as an example, MATLAB mathematical model and PSCAD simulation model are established, and the correctness of the proposed method for suppressing MMC HVDC high-frequency oscillation is verified by MATLAB mathematical calculation and PSCAD electromagnetic transient simulation.