Unbalanced Voltage Sag Ride-Through of a Doubly Fed Induction Generator Wind Turbine with Series Grid Side Converter

Regulatory standards for grid interconnection require wind generators ride-through disturbances such as faults and support the grid during such events. Conventional accommodations for providing voltage sag ride-through for doubly fed induction generator (DFIG) wind turbines result in compromised control of the turbine shaft and grid current during unbalanced faults. This paper presents analysis and control design of a DFIG wind turbine with series grid side converter for ride through during unbalanced voltage sag events. A dynamic model and control structure is developed for unbalanced operating conditions. Experimental results from 2kW laboratory hardware are used to verify the proposed concepts. Hardware results illustrate excellent ride through response of the DFIG system under various sag conditions.