On the basis of eletromechanical dynamics and electrical theory, we established a uniform mathematic model for a generator set power network. This model was a nonlinear differential dynamic system that had 27 dimensions. It consisted of the following 5 parts: the mechanical torsional equations, the synchro generator transient process equations, the prime motor torsion allocating and speed modulation control equations, and the field excitation modulation control equations. We used the series capacitor Xc and the resistance R of the transportation line as the bifurcation parameters and derived the area figure of destabilizing parameters from computing. At the point where two pairs of pure imaginary eigenvalues occured, we reduced the dimensions of the system through central manifold theory. Then, using the multiparameter stability theory and unification technique, we solved the reduced equation and obtained the bifurcation equations and their solution. Finally, we obtained the diagram of bifurction parameters, dynamic characters in four parametric areas, and the result was verified by numerical calculation.