不对称弱电网下，双馈风机与电网阻抗之间存在正序、负序间的耦合通路，交互作用复杂。由于并网导则要求风机需向电网提供正、负序动态无功支撑，若正、负序电流设置不合理，系统将有失稳振荡风险。对此，本文首先采用谐波线性化方法建立了双馈风机并网系统的序阻抗模型，阐释了正序有功、正序无功、负序无功电流对系统稳定性的影响规律，并对序间耦合致稳机理进行了分析。进一步地，计及稳定性约束、并网导则约束与变换器容量约束，对双馈风机的运行域进行了刻画。针对双馈风机稳定运行域不足的问题，提出了一种振荡自适应抑制锁相方法，实现了对锁相环输入振荡分量的自适应抑制，进而扩展了双馈风机的稳定运行域。最后，仿真算例验证了理论分析的正确性及所提控制方法的有效性。

When an asymmetric fault occurs in the weak grid, there are coupling paths of the positive- and negative-sequences between the doubly-fed wind turbine (DFIG) and the grid impedance. And the interaction is very complicated. Considering that the grid codes require the wind turbines to provide positive- and negative-sequence dynamic reactive currents to the faulty grid, if the currents are not set reasonably, the system will have the risk of instability. In this paper, the harmonic linearization method is used to establish the sequence-impedance model of the grid-connected DFIG system, and the influence law of the positive-sequence active and reactive current, and the negative-sequence reactive current on system stability is explained. And the inter-sequence coupling stabilization mechanism is analyzed as well. Furthermore, considering the stability constraints, the grid codes constraints and converters’ capacity constraints, the operation domain of DFIG is characterized. To solve the problem of insufficient stable operation domain of DFIG under weak grid, an adaptive phase-locked method is proposed to realize the suppression of the oscillation component, which in turn extends the stable operation domain of the system. Finally, the simulation examples verify the correctness of the theoretical analysis and the effectiveness of the proposed control method.