Simulation research for LVRT of DFIG with active IGBT Crowbar

The LVRT control strategy and protection schemes of DFIG are discussed in condition of large external voltage dip.On the basis of analyzing active IGBT Crowbar circuit topology as well as the effect of the Crowbar circuit to the fault during grid voltage dip,the DFIG mathematical model with considering the changed grid voltage is adopted and the control model of LVRT is established.The switching strategy of Crowbar is researched in detail during simulation.The simulation results verify that Crowbar circuit and the control strategy are active and prove that Crowbar control strategy could limit the over current in the rotor and the over voltage of the DC bus as well as the transient oscillation of the electromagnetic torque efficiently.Moreover,a reactive current is injected into the grid to assist the recovery of the grid voltage,which is in favor of achieving the LVRT of DFIG.