Modified DPC for DFIG based Wind Power Generation under Unbalanced Grid-Voltage

This paper presents a modified direct power control (DPC) strategy for a doubly fed induction generator (DFIG) based wind power generation system under unbalanced grid-voltage conditions. The strategy is based on the investigation of the mathematic model and the composition of the instantaneous active and reactive power outputted by DFIG. It is found that, by applying a notch filter of two times of the grid frequency, the proposed DPC strategy is capable of the unbalanced fault ride through operation. By compensating the errors caused by DFIG parameter mismatch, the control robustness of the proposed DPC scheme has been further enhanced. Simulation results verified that the proposed strategy is simple in control structure and have excellent dynamic performance for the reason of avoiding the computation of the negative sequence component current, and therefore, the corresponding current control loops are unnecessary.