Investigation and modeling of transient voltage stability problems in wind farms with DFIG and crowbar system

The behavior of wind farms with doubly fed induction generators (DFIGs) in fault ride through (FRT) conditions is investigated in the first part of this article. The requirements mandated by grid-codes to contribute to the voltage stability are introduced. Afterwards, the problems associated with applying the crowbar system in FRT conditions are discussed. In the next part, modeling of this problem in huge wind farms is presented. For this purpose, an equivalent model for a group of DFIGs is developed. The proposed equivalent model is based on the concurrency of the active-crowbar spans of the individual DFIGs. The comparison between simulation results with the detailed model proves the validity of the proposed equivalent model.