Dynamic mechanisms of voltage collapse

Abstract

This paper presents the result of a thorough voltage stability analysis of a simple power system. Three mechanisms of dynamic voltage collapse are incorporated: generator excitation limit, load dynamics and on-load tap-changer. The effect of each individual mechanism is analyzed first and then the combined effects are used to reconstruct a voltage collapse. It is observed that the voltage stability region shrinks as the generator operates at the excitation limit. It is also found that the appropriate time to lock the on-load tap-changer is when the system trajectory enters the region where the load voltage increases.