High-Frequency Oscillation Suppression in a PMSG-Based Grid-Connected System via a Current-Feedback Active Damping Strategy with Coordinated Multi-Index Tuning

Abstract

This paper proposes a current-feedback active damping strategy to address the high-frequency oscillations in permanent-magnet synchronous generator (PMSG)-based grid-connected systems. The core idea is an active damping controller with coordinated multi-index tuning that jointly considers the impedance–intersection margin, dominant-resonance suppression depth, sideband component increment, and total harmonic distortion. First, positive- and negative-sequence GSC output impedance models are established by incorporating the inner current loop, phase-locked loop, sampling delay, and filter dynamics, and their accuracy is verified through frequency sweep tests. Based on these models, the high-frequency stability mechanism is analyzed using an impedance-based criterion, and parameter sweep studies identify the key control and delay parameters affecting the high-frequency impedance characteristics. Subsequently, a current-feedback active damping controller is designed to reshape the GSC output impedance while minimizing its influence on non-target frequency components. Finally, case studies demonstrate that the proposed strategy eliminates adverse high-frequency impedance intersections and suppresses the target oscillation. Comparison with a virtual-admittance method further confirms a more favorable balance between stability enhancement and power-quality preservation under the investigated operating condition.