Generator Coherency Using the Hilbert–Huang Transform

Coherency between generators is tracked, by examining the instantaneous phase differences among interarea oscillations and swing curves in disturbed multiarea power systems. Huang´s empirical mode decomposition is applied to extract dominant oscillatory modes from interarea oscillations/swing curves. Hilbert transform on these modes yields their instantaneous phase. The coherency is thus revealed by the temporal evolution of the phase difference among interarea oscillations/generator swing curves. The technique is illustrated using simulations on a test system, as well as actual wide-area measurements.