Comparison of short-circuit current contribution of Doubly-Fed induction generator based wind turbines and synchronous generator

The IEC-60909 is based on assumptions that may not be valid for Wind Turbines (WT) with Doubly-Fed Induction Generator (DFIG-WT), since the DFIG has a different short-circuit response compared to the synchronous generator (SG). This paper presents a comparison of short-circuit behaviors of DFIG and SG based on IEC-60909 definitions, in order to assess the differences between the two generators, as a first step for establishing a mathematical model to predict DFIG-WT short-circuit current and evaluating the suitability of IEC-60909 for DFIG-WT. A nonlinear optimization was used to extract the different components of the fault current by fitting a model based on the IEC-60909 short-circuit definition to the simulated short-circuit current. The results show that the DFIG has a different short-circuit response compared to the SG; also that the IEC-60909 short-circuit definitions are not suitable to the DFIG.