Combination of super capacitor-switch type fault current limiter for LVRT enhancement of DFIG wind turbines

An enhanced low voltage ride through (LVRT) control strategy for a doubly fed induction generator based wind energy conversion system (WECS) is presented in this paper. The control for the rotor side and grid side converter is simple compared to the other methods. And pitch control will enable when the rotor speed increase beyond the rated value to protect WECS. Grid side converter (GSC) control reduce the DC link fluctuation and rotor side converter (RSC) control decreases the transient current during the period of fault. The advantages of energy storage to improve the LVRT is also utilized. The Switch type fault current limiter (STFCL) effectively reduce the over current in the rotor side during the fault. Fault current limiting inductors are placed in series with the stator to limit the rotor over current during the fault. SFCL absorbs the excessive energy stored in the stator during the LVRT, for the protection of converters. The feasibility of the proposed method is validated by MATLAB/SIMULINK studies on a 1.5 MW DFIG system.