Estudo de estabilidade transitória de sistemas de potência usando o método direto de lyapunov.

Abstract

The present work aims to apply the Lyapunov Direct Method in the analysis of the transient stability of power systems of multiple machines. With the machines represented by the classical model and the system reduced to the internal bars of the machines, the Lyapunov function (V) is developed and the stable equilibrium point and the unstable equilibrium points for the system in the period of post-defect. After being known the nearest unstable equilibrium point of the stable post-defect equilibrium, the stability region bounded by b min, which is the value of the Lyapunov function at that nearest unstable equilibrium point, is determined. Then, by performing the numerical integration of the differential equations of the system in the defect period and evaluating the Lyapunov function at each integration step, the critical defect elimination time is determined when the value of the function V reaches the limit value b min. Comparisons of the obtained results are made for two systems of three and four machines, with those obtained by the Method of Numerical Integration. Also investigated are eleven Lyapunov functions indicated in the literature, and among these are selected the functions that provide the best critical times. In determining the equilibrium points of the system, the Brown Method is used instead of the Newton-Raphson method. The influence of line transfer conductivities is also observed.