ABSTRACT Low voltage disturbances may cause large transient angle excursions in grid‐forming converters (GFCs), posing a challenge to their secure operation in low‐inertia power systems. Although existing studies have primarily focused on the active power control loop (APCL), the contribution of the reactive power control loop (RPCL) to transient angle dynamics remains insufficiently explored. To address this issue, this paper proposes an adaptive RPCL strategy in which the voltage reference is regulated according to the severity of the voltage sag. A nonlinear large‐signal model is established to characterize the converter dynamics, and the stability boundary is investigated through the Lyapunov's direct method and phase portrait. The results demonstrate that the proposed strategy enlarges the admissible operating region during voltage sags, mitigates power angle oscillations, strengthens reactive power support, and enhances transient synchronization stability. Experimental results validate the effectiveness of the proposed strategy in improving the transient performance of GFCs.
Xie et al. (Sun,) studied this question.