Symmetrical and asymmetrical low-voltage ride through of doubly-fed induction generator wind turbines using gate controlled series capacitor

This study proposes a new method to improve low-voltage ride through of the doubly-fed induction generator (DFIG) wind turbines (WTs) using gate-controlled series capacitor (GCSC) in series with the generator rotor. Using GCSC, as soon as a voltage dip occurs at the generator´s terminals, the GCSC inserts its capacitor in series with the rotor, increasing the voltage seen by the rotor winding. Consequently, the rotor over-current is limited and transmission of the inrush energy to the rotor side converter is reduced. Moreover, by this method, the chopper is not required for protecting the DC-link capacitor. Unlike the Crowbar method, which control of the generator is lost during the fault, the proposed method in this study avoids the loss of control during the grid faults. To validate the effectiveness of the proposed method, extensive time-domain simulation is performed using MATLAB/SIMULINK on a 1.5 MW DFIG-based WT.