Improved Transient Voltage Support Strategy for Grid-Forming PMSG Based on DC Capacitor Voltage Synchronization

Grid-forming converters, with their voltage-source characteristics, can independently provide voltage support and thus have become a critical supporting technology for new-type power systems. However, they suffer from overcurrent risks and insufficient voltage support capability during grid faults. To overcome these shortcomings, this paper proposes an adaptive transient-voltage support strategy for grid-forming PMSG wind turbines based on DC capacitor-voltage synchronization. First, the inertia synchronization and autonomous-voltage support mechanisms of such grid-forming wind turbines are analyzed. Second, based on power-flow equations and the grid-forming topology, key factors affecting the grid-connected voltage during faults are identified, and an adaptive voltage-support strategy using fuzzy control is developed. Finally, a grid-forming wind power system is modeled on the PSCAD/EMTDC platform, where the proposed strategy raises the minimum PCC voltage to 0.62 p.u. and increases reactive power injection by 0.13 p.u. under a 70% deep sag, successfully fulfilling low-voltage ride-through requirements.