Mitigating Sub-Synchronous Resonance with Adaptive Phase-Dependent Switching in Static Sub Synchronous Series Compensator

Sub-synchronous resonance (SSR) is a critical challenge in power systems, particularly in series-compensated transmission lines, where interactions between electrical and mechanical components can lead to damaging oscillations. The Static Synchronous Series Compensator (SSSC), a FACTS device, has proven effective in mitigating SSR by injecting controllable series voltage to modify line impedance dynamically. However, conventional SSSC control strategies, often based on proportional-integral (PI) controllers, can exhibit limited responsiveness during transient disturbances. This paper explores the enhancement of SSSC performance through Phase-Dependent Switching (PDS), an adaptive technique that modifies switching behavior based on real-time phase conditions. Using detailed time-domain simulations, we demonstrate that the PDS-enhanced SSSC achieves faster transient response, better damping of oscillations, and improved stability margins compared to traditional methods. The results also highlight challenges such as increased switching losses and computational demands, necessitating further research into optimized algorithms and hardware solutions. These findings underscore the potential of PDS in improving SSR damping, ensuring more reliable and efficient power system operation.