Torque ripple suppression of DFIG under unbalanced grid voltage conditions using reduced-order generalized integrators

The voltage unbalance can introduce the torque ripples for a doubly fed induction generator (DFIG), which may bring the stress on the drive train. Thus, this paper proposes a direct power control (DPC) strategy of a DFIG for torque ripples suppression under unbalanced grid voltage conditions. Under the unbalanced grid voltage conditions, the stator reactive power pulsations are proportional to the torque ripples, the torque ripples can be suppressed by smoothing the reactive power. Then, a reduced-order generalized integrator (ROGI) for the negative-sequence components was added to the reactive power control loop, thereby constructing a proportional-integral (PI) plus a ROGI (PI+ROGI) regulator. Finally, the simulation results were provided to validate the satisfactory steady-state performance and the fast dynamic responses of the proposed DPC scheme.