“…Nonlinear phenomena in power systems like voltage collapse or interarea oscillations have been investigated by many researchers (Ajjarapu et al, 1992;Budd et al, 2002;Chiang et al, 1990;Chiang et al, 1993;Dobson et al, 1989;Seydel, 2001). Understanding these phenomena is crucial because they can cause critical situations up to blackouts.…”