基于序分量耦合分析的双馈风电机组不对称故障穿越增强方法

According to emerging asymmetrical fault ride-through (AFRT) grid codes, doubly-fed induction generator (DFIG)-based wind turbines (WTs) should inject positive sequence and negative sequence currents into the grid to attenuate the voltage unbalance. However, neglecting the dual-sequence coupling effect may result in severe AFRT performance degradation, manifesting as ineffective voltage unbalance attenuation (VUA), overcurrent, overmodulation, and loss of synchronization. This article establishes the optimal VUA model for DFIG-based WTs based on sequence coupling analysis. With the reconstruction of dual-sequence synchronous coordinate systems, as well as the introduction of auxiliary variables and constraints, the nonconvexity can be eliminated with guaranteed global optimality. Subsequently, the impact of sequence coupling on feasible domain and VUA capacity is analyzed. Finally, the experimental results demonstrate that the proposed method effectively enhances VUA while ensuring the grid-connected stability of WTs.