A Novel LVRT Control Strategy of DFIG based Rotor Active Crowbar

The fast development of wind power generation brings new necessary requirement for wind turbine to provide Low Voltage Ride-Through (LVRT) capability. The paper introduces the models of Doubly Fed Induction Generator (DFIG), converter and rotor active crowbar, and analyses characteristics of DFIG system with rotor active crowbar during grid voltage dip. A novel turn-on and turn-off control method of crowbar is presented. The turn-on of crowbar depends on the dc-link voltage, and the turn-off of crowbar depends on the time constant for the damping of the dc components in stator. The proper control of crowbar can protect rotor converter, limit dc-link overvoltage, and provide reactive power to grid via both stator and grid-side converter during the grid voltage dip. The proposed control strategy of rotor active crowbar helps DFIG system successfully achieve low voltage ride-through. The results of simulations and experiments validate the feasibility of this control strategy.