Finding and ranking load bus voltage stability severity indexes due to load reactive power changing using user-defined and modified voltage stability indices

Abstract

Recently the utility is facing severe voltage stability problems so that to satisfy end users exponential growth of energy demands. As a solution, considering high operational cost of constructing new power generation, transmission and distribution system the utility is connecting more loads on existing load buses up to their thermal limits. But in power system increasing inductive load brings voltage stability problem due to an armature reaction. Thus, if we connect an additional inductive load, the armature reaction is subtractive to the main field, resulting in voltages fall-down and hence yields further voltage collapses. In addition, since under heavy load the line absorbs more reactive power than it generates, leads to transmission line stresses and its fall down when it exceeds maximum thermal limits. Therefore, this article targets finding voltage stability margins of load buses and ranking them based on their severity indexes for reactive load power changing using user modified voltage stability indices and recommending further solutions