Robust Design of Wide-Area Damping Controllers Against Permanent Communication Failures Using LQR-Based Optimization

Low-frequency oscillation modes (LFOMs) with insufficient damping can compromise power system stability following disturbances. The increasing interconnection of large-scale power systems has resulted in a greater number of poorly damped low-frequency oscillation modes, thereby motivating the development of advanced damping control techniques, such as Wide-Area Damping Controllers (WADCs). Since WADCs rely on remote measurements, communication failures and cyberattacks can impair their operation and adversely affect system stability. This study proposed an optimization framework based on Linear Quadratic Regulator (LQR) theory for the robust design of WADCs, aiming to enhance system resilience against permanent communication failures. The WADC parameters were considered as optimization variables, and the objective function was formulated to maximize the damping ratios of the closed-loop system under both normal WADC operation and permanent communication failure conditions. Unlike conventional LQR-based approaches, the proposed methodology also considered the WADC poles as optimization variables, thereby providing additional degrees of freedom for controller design. Three metaheuristic optimization algorithms, Glider Snake Optimizer, Particle Swarm Optimization, and Sine Cosine Algorithm, were incorporated into the proposed framework, and their performance was comparatively evaluated. The IEEE 68-bus system was adopted as the test system to assess the effectiveness and robustness of the proposed methodology.