DFIG Under Unbalanced Grid Voltage

This chapter discusses the influence of unbalanced grid voltage on the performance of the doubly fed induction generator (DFIG) system, including the impacts on the grid‐side converter (GSC), rotor‐side converter (RSC), and the DFIG. It analyzes the limitations of the conventional control methods under unbalanced grid voltage. According to the analysis, the DFIG system under unbalanced grid condition suffers from the second‐order fluctuation in the electromagnetic torque, second‐order harmonic current in DC‐bus capacitor, second‐order fluctuation in DC‐bus voltage, and third‐order harmonics in the grid current. These negative effects may cause significant lifetime reduction of mechanical components and the DC‐bus capacitor, as well as deterioration of the power quality. The compatibility of the DFIG system to the unbalanced grid condition does not meet the requirements if the conventional current control scheme is applied.