Asymmetrical faults ride-through of directly driven wind turbine with permanent magnet synchronous generator

The control strategy for directly driven wind turbine with permanent magnet synchronous generator(D-PMSG)was investigated to enhance its capability of faults ride through(FRT).The positive and negative sequence components were detected by using instantaneous symmetrical components method on grid voltage.Based on the analysis of the effect on D-PMSG of grid asymmetrical faults,the grid positive sequence voltage was introduced to the calculation of gen-side rectifier reference power.The control strategy was proposed to reduce generator power based on the ratio of positive sequence and rate grid voltage.A D-PMSG model connected with grid was established.The current feedforward control was applied to inner loop and the power control was used in outer loop,for gen-side rectifier.For grid-side inverter,the negative sequence current was regulated at zero in inner loop and the DC voltage was stabilized in outer loop.Simulation results showed that during asymmetrical grid faults the proposed strategy could keep power balance of PMSG and the converters,limit the DC-voltage and maintain the inverter current symmetrical.The FRT capability of D-PMSG is improved.