DFIG Band-Specific Impedance Reshaping and Wide-Band Oscillation Suppression Based on an Impedance-Decoupling Model

The increasing integration of large-scale doubly fed induction generators (DFIGs) into power grids has led to frequent oscillation incidents, necessitating urgent research on oscillation mechanisms to ensure grid stability. This paper proposes a frequency-band-segmented impedance reshaping strategy based on an impedance decoupling model to address wideband oscillations caused by DFIG grid-connection. First, a small-signal decoupled equivalent DFIG model is established, incorporating control-loop coupling effects between machine-side and grid-side converters along with power outer-loop dynamics, enabling independent impedance analysis for both rotor-side control (RSC) and grid-side control (GSC). Subsequently, the wideband oscillations are partitioned into three bands according to DFIG's impedance characteristics, with corresponding control methods implemented: RSC alternating current (AC) current control with outer-loop parameter optimization and virtual damping for sub/super-synchronous bands; DC voltage and GSC AC current control parameter optimization for mediumfrequency band; and active damping with filtered capacitor current feedforward for high-frequency band. Simulation results validate the strategy's effectiveness in enhancing frequencydomain damping performance, improving DFIG impedance characteristics, and suppressing wideband oscillations, providing both theoretical foundations and technical solutions for oscillation mitigation in large-scale DFIG integrated power systems.