The Impact of Inverter-Based Resources (IBRs) on Cascading Failures in Power Systems

In this study, we evaluate the impact of frequency control and the penetration of inverter-based resources (IBRs) on cascading failures in power systems. The modeling of controllers for IBRs requires obtaining realistic state information during cascading failure processes. However, cascading failure events can alter system topologies and the power flow Jacobian, leading to unsolvable power flow even when an equilibrium point exists. To address this, we propose a model that tracks the steady-state voltage profiles across successive cascade generations. This model enables the incorporation of droop controllers for IBRs into the cascading failure model. Additionally, it allows for capturing the effects of the interaction between local primary frequency control and system-level frequency control on cascading failures. Numerical experiments conducted on the IEEE 118- and 300-bus systems demonstrate the effectiveness of increasing primary frequency control reserve in mitigating power outages. However, increasing the droop control coefficients, which aim to enhance system robustness, results in larger power outage sizes.