The impacts on short-circuit current and protection in distribution network caused by DFIG-based wind generation

Small scale wind power is usually accessed to distribution network as the distributed generation. This interconnected mode can greatly alleviate the negative impact of wind power and even improve the reliability of grid. However, the access of wind power will make the transient and steady characteristics of distribution network changing. This variation would cause the failure of traditional protection and control, and even affect the safe operation of power grid. In particular, because the operating condition of DFIG depends on the characteristics of grid and its control, the short-circuit current in distribution network will become more complex after the access of DFIG-based wind generation. Consequently, this article has studied on this issue. Firstly, based on the Park model of induction, this paper has analyzed the short circuit current characteristics of interconnected DFIG, and presented the analytical expression of short-circuit current contributed by DFIG. Then, this paper has analyzed the distribution of short-circuit current in distribution network. Through the analysis, the influences caused by the access of DFIG for the steady short-circuit current and the existing protections have been presented. Finally, the simulation shows these influences and also verifies the correctness of the study.