Exploring Inertia and Damping for GFM Converters with Hybrid Synchronization Control

The hybrid synchronization control (HSC) method and active susceptance controller (ASC) have been demonstrated to be effective approaches for addressing the instability of grid-forming inverters under strong grid conditions. In this paper, HSC and ASC are demonstrated to share the same essence—introducing a voltage-based synchronization loop. Furthermore, differing from previous studies that rely on small-signal analysis, this paper establishes a unified large-signal model for both HSC and ASC to characterize the inertia and damping, and to elaborate that how they affect the dynamic responses. Based on the large-signal model, it is revealed that the introduced voltage-based synchronization loop of both HSC and ASC reduces the damping and inertia, thereby resulting in a faster response and higher overshoot. The findings are confirmed by the experimental results.