Resilient Fixed-Order Damping Controller for Low-Frequency Inter-Area Oscillations in Power Systems under Communication Failures

Low-frequency oscillations (LFOs) pose a critical challenge to small-signal stability, affecting the reliable operation of interconnected power systems. These oscillations can reduce tie-line power transfer capability and compromise overall system stability. Inter-area modes can be effectively observed from multiple locations and controlled from a single point, motivating the use of a wide-area damping controller (WADC). This paper proposes a robust, fixed low-order Two Input Single Output (TISO) controller that enhances system resilience by utilizing the two most observable wide-area signals corresponding to critical inter-area modes. Communication failures and time delays are major threats to controller performance; the latter is modeled using the Pade approximation. The controller is designed by optimizing key parameters, including the H ∞ norm, spectral abscissa, and complex stability radius. Kundur’s 11-bus system and the IEEE-39 bus test system are employed to validate the approach. Simulation results demonstrate that the proposed controller significantly improves damping of inter-area oscillations under normal conditions and maintains robust performance under communication failures and feedback delays.