Abstract
Melnikov function techniques are applied to simple power system models in which salient poles and nonlinear damping effects are considered. It will be shown that if the salient poles effect dominates the electric power output, the dynamical behaviors can be represented as a random superposition of the deterministic structure: the time-domain behaviors of trajectories are totally different even their initial conditions are close to each other while their power spectra are almost the same. Numerical experiments are performed to justify our theoretical predictions.