Assessing the Critical Stability Limits of Multi-Infeed Inverter-Based Generator Grid Connections: An Analytical Approach

Abstract

Low short-circuit strength is an increasingly topical issue in power grids, owing to the recent rapid integration of inverter-based renewable energy generators. However, the critical stability limits (i.e., voltage stability and power transfer capability) of such generators' grid connections are rarely assessed when analyzing the effects of varying short-circuit ratios. This paper presents an analytical approach for assessing the critical stability limits of multi-infeed inverter-based generator grid connections. Initially, we formulate analytic expressions for the system's theoretical, critical stability limits as a function of the composite and weighted short-circuit ratios. Numerical studies predicated upon the analytic expressions subsequently explore the critical stability limits of a system comprising three paralleled grid-feeding inverters as part of a case study. Last, we use time-domain simulations to validate the conclusions drawn from the presented theoretical constructs and demonstrate the usefulness of the chosen approach.