Analysis of Low Voltage Ride through Ability of Variable Speed Constant Frequency Wind Turbine Based on Crowbar Protection

The crowbar circuit installed in the rotor side is frequently adopted by doubly-fed induction generator (DFIG) to implement low voltage ride through (LVRT) ability. Based on DFIG transient characteristic, this paper discusses the principle of choosing crowbar resistance and input lasting time from the view point of converter security, wind turbine security and wind power generation system restoring stability. A simulation model of DFIG was built. The numeric tests studied the impact of different crowbar resistances on LVRT ability of DFIG with grid voltage dip, and crowbar circuit input lasting time impact on LVRT ability with consideration of reactive power compensation ability during grid fault. The results showed that reasonable crowbar resistance and input lasting time can improve LVRT ability of DFIG and is helpful for wind power generation system to restore stability smoothly.