Theoretical Analysis of the Interaction between Power System Stability Modes with the Normal Forms of Vector Fields

Because of the strong nonlinear characteristics appearing in the modern power system, the strong interaction does exist between the angle stability and the voltage stability, which were conventionally studied insularly. However, as power system is a complex unified system, the angle instability always happens together with the voltage instability. The authors propose a novel method to analyze such kind of stability problem. In the proposed method, the theory of normal forms of vector fields used to treat a auxiliary dynamic system according to the power system. By use of this method, the interaction between response modes caused by the nonlinearity of power system can be analyzed. Consequently, the eigenvalue analysis method is extended to cope with performance analysis of power system with heavy nonlinearity. The effectiveness of the proposed methodology is verified on a 4-bus power system, and some conclusions are reached.