Research on fault ride-through capacity of direct driven wind turbine with permanent magnet synchronous generator under grid asymmetric faults.

The problem that negative sequence component of dc-link voltage will produce second oscillation under grid asymmetric faults for direct driven wind turbine with permanent magnet synchronous generator (D-PMSG) has been paid more attentions in recent years. In this paper, a new control strategy to eliminate the influence of negative sequence component to dc-link voltage is proposed by delaying 60° for the single-phase voltage to construct balanced three-phase voltage. The current feed forward is applied to inner loop, while the voltage control is used to outer loop for grid-side converter, where the dc-link voltage is stabilized. The power congestion on dc side of D-PMSG under grid asymmetric faults is solved by using the energy discharge circuit. Besides, the improved minimum energy compensation strategy is embed into the dynamic voltage restorer, which can provide the maximum reactive power support for system and compensate the faulty line voltage. The effectiveness of the proposed control method is verified by simulation results. [ABSTRACT FROM AUTHOR]