Study of fault ride-through for DFIG based wind turbines

Wind power generator and total capacity has increased dramatically in the last 10 years. Most generators now being installed use doubly-fed induction machines (DFIGs). These allow active and reactive power control through the rotor side converter. Therefore today´s wind turbines have a significant impact on the power system. To ensure power quality, several utilities have introduced special grid connection codes for wind farm developers. The requirements range from reactive power control, frequency response and, last but not least, fault ride-through. All these requirements, especially fault ride-through, are a challenge for wind turbine producers. New control strategies and hardware are needed which utilize the flexibility provided by the DFIG converters. This paper outlines the proposed grid codes. It then describes a detailed DFIG model and control strategy. The performance of the new control through severe fault conditions is demonstrated.