An improved fault current calculation method and protection scheme of Doubly-fed Induction Generator

Existing research on Doubly fed Induction Generator (DFIG) short-circuit current studies are based on hypothesis the rotor current is zero when the Crowbar is input after the fault, which ignores the impact of rotor current attenuation process. It would bring the error to the calculation results. To solve this problem, on the basis of analyzing variation process of DFIG’s transient equivalent potential and the influence of rotor current attenuation process, the flux is calculated accurately. An accurate calculation equivalent model for DFIG short-circuit current is proposed. With the RTDS, an experiment platform with physical controller of converter is founded, the proposed model is validated. The effect of short circuit current to wind farms transmission line is studied, and an improved protection scheme is put forward.