Mitigation of Sustained Oscillations Caused by IBR Controller in Weak Grid Interconnection

Sustained oscillations in power systems are serious threats to grid stability, potentially leading to cascading failures, accelerated equipment degradation, and significant safety risks. Rapid identification and mitigation of these oscillations are crucial to prevent extensive outages and infrastructure damage. The increasing penetration of inverter-based resources in modern power systems has introduced new stability challenges, particularly in weak grid conditions characterized by a low short circuit ratio. One of the major causes of sustained oscillations in such systems is improper controller tuning, which can lead to resonance and system instability. This paper identifies the specific controllers contributing to these oscillations and analyzes their impact on system dynamics. A systematic approach is proposed to detect and mitigate the instability by optimizing controller parameters, ensuring stable operation under weak grid conditions. The effectiveness of the proposed tuning methodology is validated through a single machine connected to an infinite grid simulation system, demonstrating significant improvements in system stability and dynamic performance.