Synchronization Stability Enhancement of Virtual Synchronous Generators Based on Transient Switching Control

Ensuring transient synchronization stability in Virtual Synchronous Generators (VSGs) is critical for power grid reliability. While prior studies predominantly optimize active power control loops (APCLs), the role of reactive power control loops (RPCLs) remains relatively underexplored. This work proposes a RPCL switching strategy that activates constant voltage regulation during grid faults, effectively enhancing synchronization stability. The large-signal model under the proposed control is first established. Subsequently, the fundamental stability mechanisms are elucidated through phase portrait analysis. It is demonstrated that maintaining a constant output voltage during the transient process expands the stable operating region as well as mitigating frequency deviation. Finally, hardware-in-the-loop (HIL) experiment are presented for verification.