Capability of asymmetrical grid faults ride-through for DFIG-based Wind turbines

In order to meet the grid codes and ensure safe operation of doubly-fed induction generator (DFIG) based wind energy conversion system (WECS) during asymmetrical grid faults, firstly, this paper designs low voltage ride-through (LVRT) control schemes for the back-to-back converters of DFIG-based WECS. Then, due to the converter capacity constraint, the controllable regions of DFIG during asymmetrical grid faults are analyzed by optimal method while the asymmetrical LVRT limitation of DFIG is given, which points out that DFIG-based WECS can achieve LVRT only under mild asymmetrical fault situations. At the last, a typical simulated system of a 9 MW DFIG-based wind farm connected into power system is used for case study. The simulation results validate the accuracy of the analysis for the asymmetrical LVRT capability of DFIG-based WECS.