Enhancement of low voltage ride-through capability for wind turbine driven DFIG with active crowbar and battery energy storage system

This paper proposes a combined protection and control strategy to enhance the low voltage ride-through (LVRT) capability of a wind turbine driven doubly fed induction generator (DFIG). Since the conventional crowbar is activated to protect the rotor side converter during the fault interval, the DFIG will operate in the fix speed mode and absorb large amount of reactive power from the grid. This problem can be improved by using a hysteresis control scheme for the crowbar protection to minimize its operation time. Furthermore, considering the voltage ripple in the DC link side under fault condition, a battery energy storage system (BESS) connected to the DC bus is controlled to attenuate the DC voltage ripple via absorbing the redundant power stored in the DC link capacitor. Simulation results show the effectiveness of this combined protection and control strategy.