The integration of a high proportion of renewable energy sources via power electronic devices poses significant challenges to power systems. Their grid-connection characteristics differ considerably from those of synchronous generators, leading to a reduction in system inertia. Furthermore, the complex interactions between renewable energy units and the power grid substantially impact the transient stability of the system. Based on the virtual synchronous control characteristics of grid-forming wind turbines (GWT), this paper proposes an adaptive control method to enhance system transient stability. Firstly, a transient stability model for integrating GWT into conventional power systems is established, considering their control structure and typical control strategies. Subsequently, the power interaction mechanism between GWT and synchronous generators is analyzed, revealing the relationship between system stability and the active power control loop of GWT. An improved transient stability assessment index is introduced to quantify the influence of this control loop on system transient stability. Based on this, using the rate of change of virtual rotor speed and the depth of voltage dip as criteria, a flexible inertia control method for grid-forming wind turbines based on adaptive switching of virtual synchronous control is designed, achieving an enhancement in the power system’s transient stability. Finally, a simulation model is built on the DIgSILENT/PowerFactory platform. The simulation results demonstrate that the proposed control method effectively suppresses rotor angle instability in synchronous generators and significantly improves the system’s transient stability.
Luo et al. (Thu,) studied this question.