PARALLEL INTERLEAVED CONVERTERS AND DYNAMIC RESISTOR IN A DFIG WIND TURBINE DURING THREE PHASE FAULT

Abstract: The fast development of wind power generation brings new requirements for wind turbine integration into the network. After clearance of an external short-circuit fault, grid-connected wind turbines should restore their normal operation without power loss caused by disconnections.During the fault by flowing the high current for a several micro seconds transient operations are very crucial for high power insulated-gate bipolar transistor modules. Therefore, the ability for doubly fed induction generator (DFIG) variable speed wind turbine power converters to withstand abnormal conditions is strictly imperative in order to achieve its lifetime specifications and also fulfil the grid codes. In this paper presents a new control scheme for DFIG wind turbine having parallel interleaved converters (PIC) configuration and a series dynamic braking resistor (SDBR) connected at its stator side.Interleaving the wind turbine converters in parallel configuration could help to increase the current capability, while the SDBR helps in post fault recovery of the wind turbine and also used for used to improve the FRT of large wind farms composed of induction generators. The shorter duration of operation of the SDBR gives a better response of the DFIG system during a grid fault. The coordinated control analysis of the scheme was implemented in power system computer aided design and electromagnetic transient including DC simulation environment for a severe three-phase to ground fault. A better performance of the wind turbine variables were achieved using the proposed control scheme of the PIC and SDBR because the space vector modulation of the PIC results in maximum value of the change in common mode voltage, leading to improved switched output voltage of the voltage source converter leg.Simulation results were obtained compared with the conventional DC chopper and crowbar rotor circuit protection scheme for the wind turbine and also demonstrate that in uncritical post-fault situations the control schemes are able to restore the wind turbine's normal operation without disconnections.