Physical Insight Into Hybrid-Synchronization-Controlled Grid-Forming Inverters Under Large Disturbances

This letter analyzes the impact of hybrid voltage- and power-based synchronization control on the transient stability of grid-forming (GFM) inverters. It is found that the added voltage-based synchronization loop exploits the phase angle difference to resist frequency deviation, whose function is similar to the damper winding of synchronous generators. By resembling the large-signal model of such hybrid synchronization control (HSC) to the power-angle swing equation, it is proved that the HSC brings higher damping to the system and thus, enhances the transient stability of GFM inverters. Further, a comparative study of two active power controllers, i.e., the droop controller with a low-pass filter and the proportional-integral (PI) controller, is given. It is revealed that the HSC with the droop controller equivalently decreases the active power reference, which leads to better transient stability behavior than that of using the PI controller. The theoretical findings are corroborated by experimental tests.

Automated summary

This study analyzes the impact of hybrid voltage- and power-based synchronization control on the transient stability of grid-forming inverters, showing positive effects on enhancing system damping and transient stability. A comparative study of two active power controllers reveals that using the droop controller in the hybrid synchronization control significantly decreases the active power reference, leading to better transient stability behavior compared to using the PI controller. The theoretical findings are supported by experimental tests.