A Fast IVS Control for Grid-Forming Converters to Enhance Transient Stability and Accelerate PCC Voltage Recovery in Weak Grids

This paper proposes a fast internal voltage source (IVS) controller for grid-forming (GFM) voltage source converter (VSC) to enhance the transient stability. While conventional methods frequently suffer from degraded synchronization performance due to current limitations, the proposed approach significantly reduces the post-fault transient period during which the current limiter remains active. In particular, when a phase jump fault occurs in a weak grid, a GFM-VSC staying in the current-limited state for an extended time exacerbates the recovery of the point of common coupling (PCC) voltage. Therefore, applying the proposed controller to the GFM-VSC can notably improve the PCC voltage recovery speed after a phase jump fault in a weak grid. The effectiveness of the proposed control is demonstrated through down-scaled experiments.