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

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 droopbased 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. ... mehrFor the considered setups and used tuning procedures, virtual-admittance yields larger maximum currents than proportionalintegral/resonant voltage control, and rotating-frame proportional-integral voltage control shows improved
damping compared to the stationary-frame alternative