Improvement of the Consideration of Short-Circuit Current Contributions from Doubly-Fed Induction Generator Based Wind Turbines For Short-Circuit Current Calculation According to IEC 60909

In this paper an improved approach to consider the contribution of wind turbines based on doubly fed induction generators (DFIGs) for short-circuit current calculation according to IEC 60909 for a three-phase short-circuit is presented. The calculation with the equivalent voltage source at the fault location requires a simplified modelling of short-circuit contributions through impedances or current sources, whereas specific control algorithms cannot be considered. Additionally these impedances or current sources must be calculated with basic and publicly available machine parameters. The improved approach is based on equivalent circuit elements, derived from eigenvalue analyses meets the aforementioned requirements and is compared to a detailed numerical simulation model, which shows the influence of the dynamic control structure. The improved approach delivers a good estimation for the calculation of the maximum initial short-circuit current in each case. Finally, a suggestion for the consideration of DFIG, based on the improved approach is made.