Modeling of wind power plants for short circuit analysis in the transmission network

This paper presents guidelines for estimating short-circuit contribution from wind power plants to the transmission network. Only squirrel-cage induction generator based turbines have been considered. A commercial software package has been used to model the plant in detail. Transient analysis is performed to explore the nature of the plant short-circuit current. AC symmetrical short-circuit currents are calculated and used through a network reduction technique to obtain the equivalent positive and zero sequence impedances for the wind power plant. Case studies have been performed on a sample 50 MW wind power plant. The plant contribution during the initial cycle of the fault (asymmetrical current) can be as high as 6 or more times the rated turbine current. As the fault persists, the contribution decreases in magnitude. Comparison shows that the equivalent circuit gives identical results to the detailed model. The equivalent circuit can be used to represent the wind power plant in short-circuit analysis at the transmission level.