基于内电压矢量的双馈感应风力发电机故障穿越不对称电网形成控制

Grid-forming (GFM) controls exhibit robust frequency and voltage support capabilities for inverter-based resources (IBRs). This also shows promise for doubly fed induction generator-based wind turbine generators (DFIG-based WTGs). However, during asymmetrical faults, the DFIG-based WTG that employs GFM controls (GFM-DFIG) might suffer from overcurrent and overmodulation of the rotor-side converter (RSC). Therefore, from the perspective of positive-sequence, negative-sequence, and transient components, this paper proposes asymmetrical fault ride-through (FRT) controls for the GFM-DFIG based on the mechanism for forming the grid voltage. Firstly, internal voltage vectors are designed for the assessment of asymmetrical FRT capabilities. Then a positive- and negative-sequence control (PNSC) is proposed to support the sequence components of internal voltage vectors for the GFM-DFIG. On this basis, an asymmetrical FRT control structure is proposed, incorporating negative-sequence reactive current injection and two types of positive-sequence control schemes: the current saturation-based method and virtual impedance-based method. Additionally, a simplified calculation method for transient voltages is utilized to eliminate the impacts of transient flux leakage. Finally, the proposed FRT controls for the GFM-DFIG are validated by using the EPRI benchmark system. The results indicate that, with the proposed control, GFM-DFIG can maintain stable voltages and achieve required negative-sequence behaviors.