Active Damping of Power Control for Grid-Forming Inverters in LC Resonant Grids

This paper derives the small-signal model of grid-forming (GFM) inverters considering the presence of the shunt capacitor in the power grid. It is found that the shunt capacitor introduces two additional resonant peaks in the loop gain of power control loops, in addition to the fundamental-frequency resonant peak that is identified in the prior art. Based on the findings, the active damping control is modified to dampen all three resonant peaks to guarantee the stable operation of GFM inverters. Finally, simulations and experimental tests are carried out to corroborate the theoretical findings.