Application of DC Chopper to Augment Fault Ride Through of DFIG Based Wind Turbine

Transient analysis is an important feature of doubly fed induction generator (DFIG). In this paper, for enhancing fault ride through (FRT) capability of DFIG based wind turbine a DC chopper is used which is connected across the DC-link capacitor. Two schemes were observed; the first scheme uses one insulated-gate bipolar transistor (IGBT) switch in series with a resistor to show the effect of the DC chopper magnitude. In this scheme, the best DC chopper resistor was obtained. The second scheme uses a circuit breaker to determine the best insertion time and duration of operation of the DC chopper. Proposed schemes were applied to a DFIG to investigate the transient analysis. Simulations were done by using PSCAD/EMTDC software. Simulation results show the DC chopper can adequately improve the FRT capability of the DFIG and also show the DC chopper resistor should be chosen carefully, because during a grid fault the large value may affect the system performance.