Grid-connected wind power generators in wind farms require low voltage ride-through functions to meet grid failures, especially uninterrupted operation under grid voltage sag failures. Therefore, aiming at the shortcomings of conventional Crowbar, this article designs a protection scheme based on the combination of Crowbar and DC-Chopper. A wind farm simulation model was established, and the short-circuit current output characteristics of a wind turbine with low voltage ride through capability (LVRT) under asymmetric fault and symmetric fault conditions were simulated. And verified its optimized performance.

DFIG; Crowbar protection; DC-Chopper circuit; Symmetrical short circuit fault; Asymmetric short circuit fault;