Sliding-Mode Control for DFIG Rotor- and Grid-Side Converters Under Unbalanced and Harmonically Distorted Grid Voltage

Regarding doubly fed induction generator (DFIG) operation, unbalanced and harmonically distorted grid voltage conditions have been treated as two separate control problems. This paper reports a solution for the rotor- and grid-side power converters, which allows one to keep the DFIG successfully in operation under both grid voltage conditions. The proposed solution is based on sliding-mode control (SMC). The rotor-side converter is commanded so that the electromagnetic torque and the stator reactive power remain free of fluctuations that arise during grid voltage disturbances. Meanwhile, the grid-side converter ensures both constant DC-link voltage and steady active power output from the overall system. The developed algorithms turn out being robust against parameter variations and of fast dynamic response. In addition, none of the converters need either voltage or current positive and negative sequences extraction. The simulation results presented demonstrate the appropriateness of SMC to face such disturbed scenarios. Finally, the stability proof of both converters´ control algorithms is provided in the appendices.