Impacts of Grid-Forming IBRs with Time-Duration Ratings on Quadrilateral Ground Protection

Power engineers have been challenged to design grid-forming (GFM) control strategies for inverter-based resources (IBRs) so that they can ride through faults without impacting classical line protections. This paper analyzes whether the GFM IBRs equipped with two-axis anti-windup proportional-integral regulators embedding circular limiters can: (i) Ride through faults without violating time-duration ratings which is critical to ascertain semiconductor thermal stress. (ii) Inject asymmetrical currents without overly distorting current waveforms to not impact the computation of phasors for protection purposes. These findings are deduced from key formulations and PSCAD simulations of a modified version of the WSCC 9-bus grid that is only powered by wind and photovoltaic IBRs.