By using Hopf bifurcation theory to analyze the stability operation of electric power systems, the nonlinear characteristics of nonlinear systems can be totally involved and the instability reasons for systems be revealed further. While to calculate the Hopf bifurcation points, the previous methods involve a great deal of computation of the eigenvalues of system's Jacobian matrix and decision whether the real parts of the eigenvalues were zero when there exist any change of the parameters in the system. In...