Transient Stability Region of Power Systems Using Series Expansion of Lyapunov Function

Abstract

In this paper, a method is proposed for improving the accuracy of the stability criterion by enlarging the estimation of the stability region determined by means of Lyapunov's direct method using the.series expansion, and by putting it closer to the actual stability region. The Lyapunov function by the energy integration is used as the first estimation. The method is applied to a single-machine infinite bus power system, and the stability domain in the δ―ω plane is shown together with the actual stability domain obtained by numerical integration. It is shown that the application of the proposed method results in a considerable improvement of the stability boundary estimation over that given by the original Lyapunov function. Zubov's method, which obtains an accurate stability boundary using the series expansion, is related to the method proposed in this paper. The last section is, therefore, devoted to comparing the two methods and examining the possibility of their application to multi-machine power systems.