Improved Control Strategy for Low Voltage Ride Through Capability of DFIG with Grid Code Requirements

This paper deals with a protection and control strategy to enhance the low voltage ride through capability of a wind turbine driven doubly fed induction generator (DFIG). As the wind power penetration continues to increase, wind turbines are required to provide Low Voltage Ride-Through (LVRT) capability. Crowbars are commonly used to protect the power converters during voltage dips and their main drawback is that the DFIG absorbs reactive power from the grid during grid faults. According to emergency grid code requirements, wind farms should have the ability to stay connected and continue generation under external voltage failure conditions, that is, wind turbines have to keep in connection with grid and own continue reactive power supply. This paper proposes a hysteresis current control strategy for the crowbar protection and a reactive power control to satisfy the grid code requirements. Consequently, the dynamic model of double fed wind turbines is established to study the transient behavior of DFIG. Simulation results are presented to show the effectiveness of the proposed control scheme.