Time-Scale Separation in Power System Swing Dynamics: Singular Perturbations and Coherency

Abstract

Large power systems often exhibit slow and fast electromechanical oscillations between interconnected synchronous machines. The slow interarea oscillations involve coherent groups of machines swinging together. This coherency phenomenon can be attributed to the coherent areas of machines being weakly coupled, either because of higher impedance transmission lines, heavily loaded transmission lines, or fewer connections between the coherent areas compared to the connections within a coherent area. Singular perturbations can be used to display the time-scale separation of the slow interarea modes and the faster local modes.