Impact of Crowbar Resistances on Low Voltage Ride Through of Doubly Fed Induction Wind Turbine Generation System

Abstract

The impact of crowbar resistance on low voltage ride through (LVRT) of doubly-Fed induction generator (DFIG) is researched. The relationship between the crowbar resistance and the rotor transient current and the attenuation rate of stator rotor transient flux is derived. It is proposed to add series dynamic capacitor in crowbar circuit to decrease the absorbed reactive power. Results show that, either too large or too small crowbar resistance may weaken the ability of DFIG LVRT, the optimal crowbar resistance should be selected and the additional dynamic capacitor makes the rotor overcurrent has a smaller transient time constant and a faster recovery speed for the grid fault.