Methodology for quantification of equipment trips due to voltage sags

Abstract

This paper discusses universal methodology for quantification of equipment trips due to voltage sags. Every sensitive equipment is described by the voltage-tolerance curve with specific limit values. Generally, one type of the sensitive equipment can be described by different characteristics that create an area of uncertainty, which influences the behavior of these devices. For calculation of expected number of equipment trips due to voltage sags are using various types of sensitivity equipment (e.g. personal computer, adjustable speed drive and programmable logic controller). The first general probability approach used probability density functions for bivariate random variable (magnitude and duration of the voltage sag) and the second cumulative probability approach used probability distribution functions for bivariate random variable. Moreover, the estimation of equipment trips is complemented with determining various levels of sensitivity, which is dependent on operating conditions.