A Grid Fault Tolerant Doubly Fed Induction Generator Wind Turbine via Series Connected Grid Side Converter

With steadily increasing wind turbine penetration, regulatory standards for grid interconnection are evolving to require that wind generation systems ride-through disturbances such as faults and support the grid during such events. Conventional modifications to the doubly fed induction generation (DFIG) architecture for providing ride-through result in limited control of the turbine shaft and grid current during fault events. A DFIG architecture in which the grid side converter is connected in series as opposed to parallel with the grid connection has shown improved low voltage ride through but poor power processing capabilities. In this paper a unified DFIG wind turbine architecture which employs a parallel grid side rectifier and series grid side converter is presented. The combination of these two converters enables unencumbered power processing and improved voltage disturbance ride through. A dynamic model and control structure for this unified architecture is developed. The operation of the system is illustrated using computer simulations.