Complex Impedance-Based Frequency Coupling Characteristics Analysis of DFIG-Based WT During Asymmetric Grid Faults

In this article, the frequency coupling of weak grid-connected doubly fed induction generator (DFIG) based wind turbines (WT) during asymmetric faults have received little attention. To analyze the frequency coupling phenomenon of the system during asymmetric faults, this article established the complex transfer function model in αβ frame based on the transformation relationship between complex transfer function and transfer matrix. According to the complex transfer function, the frequency coupling mechanism of the DFIG system during asymmetric faults is revealed, and the transfer evolution law of coupling frequencies is described in detail. Finally, the correction of theoretical analysis and the validity of proposed complex transfer models are verified by the simulation and experiment.