An Innovative Control Strategy to Improve the Fault Ride-Through Capability of DFIGs Based on Wind Energy Conversion Systems

An innovative control strategy is proposed for enhancing the low voltage ride-through (LVRT) capability of a doubly fed induction generator based on wind energy conversion systems (DFIG-WECS). Within the proposed control method, the current control loops of the rotor side converter (RSC) are developed based on passivity theory. The control scheme for the grid side converter (GSC) is designed based on a two-term approach to keep the DC-link voltage close to a given value. The first term based on the maximal voltage of GSC is introduced in the GSC control loops as a reference reactive current. The second one reflecting the instantaneous unbalanced power flow between the RSC and GSC is also introduced in the GSC control loops as a disturbance considering the instantaneous power of the grid filter to compensate the instantaneous rotor power. The effectiveness of the proposed control strategy is verified via time domain simulation of a 2.0 MW-575 V DFIG-WECS using PSCAD/EMTP. Simulation results show that the control of the DFIG with the proposed approach can improve the LVRT capability better than with the conventional one.