Damping Method for Multiple Small-Signal Oscillation Modes in the DC-Link Voltage of GFM VSCs With Matching Control

Small-signal oscillations in the DC-link voltage significantly limit the widespread application of grid-forming (GFM) voltage source converters with matching control (MC-VSCs). While some damping methods have been proposed, their effectiveness under practical conditions has not been systematically evaluated, making it impossible to guarantee the mitigation of all oscillation risks. To fill this gap, this article first identifies all potential oscillation modes utilizing the small-signal model of the MC-VSC. Then, the damping effects of existing methods for the MC-VSC are quantitatively evaluated. Results indicate that existing oscillation-damping methods are similar in structure and fail to dampen all oscillation modes. To holistically dampen all identified oscillation modes, this article first proposes a simple and equivalent proportional integral derivative (PID)-based matching control strategy; then, a Biquad filter (BF)-based enhancement method is proposed specifically to dampen oscillation modes that existing methods fail to suppress effectively. The proposed method, combining the PID-based matching control with the BF-based method, demonstrates great potential for practical application. Simulations and experiments verify the accuracy of theoretical analysis results and the superiority of the proposed stability enhancement method.