This letter revisits vector voltage control (VVC) and finds that by introducing a P-E-q droop into the q-axis voltage reference, a conventional phase-locked loop (PLL) can effectively substitute the power synchronization control for replicating the power-frequency (angle) dynamics of grid-forming (GFM) inverters. Consequently, a simple GFM control strategy that retains the traditional PLL and VVC is proposed. In contrast to recently reported PLL-based GFM approaches, the method eliminates the need for virtual admittance control and offers higher stability robustness across a wide range of grid short-circuit ratios.

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.