Large disturbance voltage stability assessment using extended Lyapunov function and considering voltage dependent active loads

The main concern of this paper is the proposal of an extended Lyapunov function (ELF) for a power system model that does not have Lyapunov function in the usual sense. More precisely, an ELF is proposed for a network preserving model where both, the active and reactive load powers depend on voltage. Then the proposed ELF is used for short term stability analysis including voltage and angle instability phenomenon. The results show that the proposed function can be used to obtain good estimates of the critical clearing time.