Evaluating Grid Strength with Rising Penetration of Inverter Based Resources

Abstract

Over the years, Dominion Energy Virginia (DEV) has experienced recurring power quality disturbances, including voltage and power oscillations, particularly in areas with significant inverter-based generation. While these phenomena suggest a potential relationship to system strength, no definitive correlation has yet been established. This paper presents methodologies for assessing system strength across the DEV network and identifying regions that may be vulnerable to such disturbances. To this end, three grid-strength metrics are evaluated: the Simple Short-Circuit Ratio (SSCR), the Weighted Short-Circuit Ratio (WSCR), and the Composite Short-Circuit Ratio (CSCR). Historical event data will be analyzed using steady-state snapshots from DEV's proprietary Analysis on Demand (ANODE) platform, which provides 10-minute interval load-flow data. These snapshots will be processed using a developed software tool to compute system strength metrics. The analysis will investigate potential correlations between system strength and observed disturbances. Where such correlations are identified, the study will further evaluate the impact of deploying synchronous condensers (SynCons) as a mitigation strategy.