Small-Signal Stability Enhancement of Grid-Side Converters for Permanent-Magnet Wind Turbines via Adaptive Leaky Impedance-Reshaping Compensation

Abstract

Grid-following grid-side converters (GSCs) in permanent-magnet wind turbines may lose small-signal stability in weak grids because the synchronous reference frame phase-locked loop (SRF-PLL) interacts with grid impedance. For a regulated direct-current (dc) side, this paper proposes power-scheduled leaky impedance-reshaping compensation while retaining the original SRF-PLL and vector current control (VCC) structure. A bounded angle-reconstruction path and power-scheduled current-reference term suppress destabilizing admittance. Small-signal analysis predicts that the stable power boundary increases from 0.609 to approximately 1.00 p.u. Hardware-in-the-loop (HIL) tests on a 1 MW, 690 V GSC model show increasingly pronounced oscillations with conventional VCC at 750 kW (0.75 p.u.), whereas the proposed method stabilizes active power, point-of-common-coupling voltage, and synchronization frequency.