Feed-forward transient compensation control for DFIG wind generators during both balanced and unbalanced grid disturbances

Abstract

A feed-forward transient compensation (FFTC) control scheme with proportional-integral-resonant current regulators is proposed to enhance the low-voltage ride-through (LVRT) capability of doubly-fed induction generators (DFIGs) during both balanced and unbalanced grid faults. FFTC terms are injected into both the inner current control loop and the outer power control loop. The FFTC current controller improves the transient rotor current control capability, and minimizes the DFIG control interruptions during both balanced and unbalanced grid faults. Furthermore, without the need of sequence component decomposition, the torque ripples are reduced by injecting 60 Hz and 120 Hz rotor current components during unbalanced stator voltage conditions. The proposed FFTC control introduces minimal additional complexity to a regular DFIG vector control scheme, and shows promising enhancements in the LVRT capability of DFIGs. A 4 MW DFIG wind turbine system is simulated to demonstrate the proposed FFTC control scheme.