Modal Analysis of Strong Resonance in Multi-Machine System with Power System Stabilizer

When two or more control parameters of a power system are altered concurrently, their improper settings may lead to strong resonance due to a modal interaction. The research focuses on the design of a Power System Stabilizer (PSS) to address this instability in multi-machine power systems. To investigate the phenomenon of strong resonance, a test system of a 3-machine, 10-bus power system with a single PSS is utilized. Both full-order and reduced-order mathematical models of the system are employed for analysis. The full-order model is leveraged for eigenvalue and participation factor analyses, aiding in PSS performance evaluation and root locus visualization. Meanwhile, the reduced-order model, obtained through multi-modal decomposition, allows for examining strong resonance characteristics using the perturbation method. The findings indicate that simultaneous alterations of PSS parameters can cause critical modes to become unstable, corresponding to strong resonance conditions.