System Strength Sensitivity to Power Flow Perturbations in AC Power Systems with Inverter-Based Resources: Preprint

As inverter-based resources (IBRs) contribute larger shares of generation in electrical power grids, their impact on the stability of these systems grows. Quantifying the strength of the system is important for identifying potential stability issues related to IBRs. Recently, new admittance model-based system strength metrics have been proposed to identify stability issues and control interactions in systems with high levels of IBRs; however, these methods depend on the linearization of nonlinear devices in power systems and must be evaluated at many operating points to understand how the state of the system impacts system strength. In this paper, we propose new system strength metrics based on the sensitivity of the small-signal stability of the system to changes in the operating point due to perturbations in power injections. We validate our approach on a 14-bus test system to show how the metrics can be used to find remedial actions for small-signal stability issues.