Simulation and Analysis on Low Voltage Ride through of Doubly-Fed Induction Generator

In case of three-phase short circuit fault occurring at the terminal of a doubly-fed induction generator (DFIG), the rotor current characters of DFIG are analyzed from the viewpoint of the flux linkage, and the expression of the rotor current is deduced together with the estimated expression of the maximum rotor current. Based on above analysis, the max rotor currents and their appearing times with different Crowbar resistances are found, and the appropriate Crowbar resistance value is set for the 1.5 MW DFIG. The low voltage ride through (LVRT) effects of DFIG with different Crowbar resistances and drop out times are analyzed and compared by simulations, and simulation results show that: the deduced expression of the rotor current and estimated expression of the maximum rotor current can accurately represent the rotor current characters when three-phase short circuit fault happens at the terminal of a DFIG; Under the condition that the grid-side PWM equipment is not over voltage, if the Crowbar resistance is reasonable large in the value range and the Crowbar drops out before the grid fault being cleaned up, the LVRT effect will be better.