Low Voltage Ride-Through protection techniques for DFIG wind generator

Due to the rapid increase of penetration level of wind generation connected directly to the bulk power system grid, a new grid codes have been issued that require Low-Voltage Ride-Through (LVRT) capability for wind turbines so they can remain online and support the electric grid post fault events instead of instantaneous tripping. This capability will increase the stability of the network and reduce generation shortage after the fault clearance. Each utility has its own grid codes for this LVRT. There are many types of wind generators, and currently the Doubly Fed Induction Generator (DFIG) is the most popular type among the leading wind turbine (WT) manufacturers. In this paper five LVRT methods for protection of DFIG during LV events are implemented and compared. The five methods are Crowbar, DC Chopper, series dynamic resistances, and two hybrid methods that combine DC chopper with Crowbar and DC chopper with series dynamic resistances respectively. These methods were tested under different types of fault including symmetrical and unsymmetrical faults and their performances were compared.