Dynamic compensation for a wind farm based on the critical slip and critical voltage

This paper, discusses about a systematic approach to calculate the dynamic compensation for a wind farm to enhance Fault Ride Through (FRT) Capability. In this approach the generator parameters like critical slip and critical voltage are probed and the size of the dynamic compensation is calculated. This method is applied to Squirrel Cage and Wound Rotor induction generators (SCIG & WRIG). The critical slip of the induction machine is calculated by using torque-speed characteristics and equivalent circuit model. The variation of real and reactive power of the SCIG or WRIG from rated slip to the critical slip is analyzed and the critical voltage is computed. The practical wind farm considered in the study has fixed speed induction generators. The capacity and location of dynamic VAR compensation is determined based on the critical voltage of the induction generators. The detailed wind farm and the grid are modeled in MiPower™ simulation environment. The improvement in fault ride through capability is analyzed for different case studies.