Sensitivity Analysis of Resonant Stability in Low-Voltage Distribution Systems with Inverter-Based Resources and Capacitor Banks

Recent growth in distributed energy resources (DERs) integration into power grids via power electronics has introduced challenges, including negative resistance behavior that reduces damping of electrical resonances. This study assesses the risk of unstable resonances in low voltage distribution systems due to interactions between inverter-based resources (IBRs) and shunt capacitor banks. A simplified LV feeder is modeled in state-space, and eigenvalue sensitivity analysis is performed by varying reactive compensation and IBR penetration levels. No instability was identified, but the risk increases especially for capacitor banks below approximately 7% of transformer power. Furthermore, the participation factors assessment indicate that the primary contributors to the region of greatest instability risk are the capacitive bank and the transformer’s inductance. Within the IBRs, the LCL filters and the controller’s digital delay also play a significant role.