Abstract
This paper presents a new type Lyapunov function of the synchronous generator with the effects of flux decay and voltage regulator. Lagrange-Charpit method is applied to the construction of the Lyapunov function. Although flux decay causes a product-type nonlinearity in the formulation of the electrical power output, a well-defined form of this nonlinearity is considered and is taken into account in the construction process. It is shown that the positive difiniteness of the obtained Lyapunov function and the negative semidefiniteness of its time derivative can be easily verified by using the nature of this nonlinearity.
The Lyapunov function may then be used to estimate the critical switching time for power-system transient stability. The critical switching times given by this Lyapunov function are compared with those obtained by conventional Lyapunov function, showing the superiority of the estimation.
