Impact of Control Architecture on Grid-Forming Inverters Under Grid Disturbances

Abstract

In inverter-dominant power systems where grid-forming inverters maintain system voltage and frequency, understanding the impact of fast-timescale responses of inverter-based resources to grid disturbances is critical. This paper investigates how the cascaded control architecture and implementation of grid-forming inverter controls impact their response to such disturbances. Focusing on fast-timescale behavior, the study evaluates the influence of inner control loops, comparing virtual admittance and proportional-integral/resonant voltage control, as well as the selected control reference frame (i.e., rotating or stationary). To examine the role of primary control on transient performance, we consider droop-based and virtual synchronous machine-based grid-forming control. Through detailed simulation studies and hardware experiments of grid-forming inverters under grid disturbances, including voltage sags, phase-angle jumps, and rapid frequency changes, this paper examines how control architecture choices shape the fast-timescale response of grid-forming inverters during transients. The results show that voltage control architecture and reference frame significantly affect transient response. For the considered setups and used tuning procedures, virtual-admittance yields larger maximum currents than proportional-integral/resonant voltage control, and rotating-frame proportional-integral voltage control shows improved damping compared to the stationary-frame alternative.