Transient Stability Assessment of Inverter-Based Resource (IBR) Cessation Mode Using Power System Simulator for Engineering (PSS/E)

The integration of inverter-based resources (IBR) in transmission and distribution systems has resulted in several reliability issues, including impacts of its advanced features in the stability of power systems. One of the features of IBR is the so-called momentary cessation (MC) where the inverter temporarily ceases injection of active power during disturbances. In this study, a transient stability assessment of an isolated power system with IBR employing momentary cessation was performed with the aid of a power system simulation program, PSS/E. Power flow and dynamic simulation models of an isolated power distribution system with photovoltaic (PV) IBR units were created. Forty-eight transient stability simulations were performed, and results showed that (a) the isochronous mode of operation (Scenario S2) of generators is preferred from a frequency control standpoint, (b) delayed clearing of faults still preserved the stability of the power system, (c) three- phase faults were proven to be the worst type of fault than the single line-to-ground fault contingencies, and (d) loss of generation contingencies resulted to large frequency deviations. In these simulations, an MC voltage threshold of 0.50 pu was used. Varying the MC voltage threshold were found out to affect the magnitude synchronous machine rotor angles based on the results of 328 sensitivity simulations conducted. Even when the fault is already cleared, the active power output of the PV IBR units showed slow recovery at higher MC voltage thresholds. This PV IBR active power characteristics during the recovery period translate to generation-load imbalance and thus negatively impacts the transient stability of the power system network.