An Equivalent Method for the Fault Circuit Current Analysis of DFIG Wind Farm

For the doubly fed induction generator (DFIG) wind farms, the fault characteristics are complex, transient characteristics of fault and short-circuit current simulation analysis is crucial, so it's important to set a new model which is applicable to the equivalence of the transient fault. In this paper, a novel fault transient equivalence method for wind farm based on rotor current peak cloud model is proposed. The numerical characteristics of cloud droplet sample are calculated through the improved backward cloud generator. The cloud droplet sample of rotor current peak value can be obtained under random wind speed and terminal voltage drop. The wind turbine generators can be clustered by the feature indices through the k-means cluster algorithm. A multi-machine equivalent model is established. Based on power loss method and weighted voltage difference method, the network transformation method is proposed, which can realize the transformation of different circuit structure, and is suitable for the aggregation of unit at any position. Reliability and effectiveness of the proposed scheme are verified by simulation results. It also provide the support for analyzing and calculating the short-circuit current and relay protection of wind farm.