Asymmetrical High-Voltage Ride Through of Brushless Doubly Fed Induction Generators for the Wind Power Generation Based on Improved Indirect Power Control

This paper analyzes and deduces the transient currents of the control winding (CW) of the brushless doubly fed induction generator (BDFIG) during an asymmetric voltage rapid-rise fault in the power grid. It indicates that restraining the overcurrent of the CW is not the key solution to the asymmetric high-voltage ride through issue of the BDFIG. Meanwhile, the relationship between the CW flux linkage, active and reactive power of the power winding (PW), and the electromagnetic torque during the fault is analyzed. The analysis results demonstrate that in order to eliminate the second harmonic components in reactive power and electromagnetic torque, negative sequence components need to be injected into the CW flux linkage. An improved indirect power control strategy is proposed, and a system structure diagram is constructed. Simulation results validate the effectiveness of the proposed control strategy, significantly mitigating the second harmonic components in reactive power and torque during asymmetric fault conditions, this reduces the pressure on the drive train and enhances the fault-ride-through capability of the BDFIG.