A study on fluctuations in electromechanical oscillation frequencies of power systems

This paper investigates the fluctuation phenomenon in the electromechanical oscillation frequency of a power system. Analysis on the power system swing equation explains that the oscillation frequency fluctuates around a central frequency due to the nonlinear system nature of a power system. A Phase-Plane Trajectory based method and the Prony method are used to track the real-time frequency fluctuation, based on which a realtime angular stability margin index is proposed for early warning of angular stability issues. That index is tested by case studies on a two-generator system and a 179-bus power system.