ABSTRACTElectric power system essentially belongs to strongly nonlinear complex dynamic system. It has strong coupling and other various dynamic characteristics. In theory, the nonlinear dynamical model associated with complex power system should exist. In this paper, we have discussed two kinds of nonlinear circuits, nonlinear RLC circuit that can be constructed to be Liénard equation model and Chua's circuit. In our research, the superstable periodic parameters of period doubling bifurcations are solved accurately, and it is also the fault characteristic in nonlinear circuits, which may represent the essential attribute of complex electric power system. The research will contribute to solving the blackout problems in real electrical engineering. It is an inevitable request that applying nonlinear dynamical system theory to the research of complex electric power system, which is not only beneficial to the effective solution of power system's own problems, but realizing new breakthroughs in nonlinear dynamical system theory by finding new problems.