Some Observations on Definitions of Voltage Unbalance

In this paper an analysis of five different definitions of voltage unbalance developed by various power communities (CIGRE, NEMA, IEEE, and IEC) is presented, in order to understand their performance and difference among them. The purpose of this work is to analyze and quantify the voltage unbalance, so that these results may become useful to minimize the harmful effects of voltage unbalance. To quantify the voltage unbalance, five existing voltage unbalance definitions are calculated and their numerical values are used in analyzing the behavior of these definitions for the unit change in their magnitude and angle of voltage phasors.