%0 Journal Article %T Probability Density Functions of Voltage Sags Measured Indices %A Zvonimir Klai %A Damir ljivac %A Zoran Baus %J Journal of Electrical Engineering %D 2011 %I %R 10.2478/v10187-011-0053-8 %X Voltage sags can cause interruptions of industrial processes, which could result as a malfunction of equipment and considerable economic losses. Thus, it is very useful to see certain rules of voltage sags occurrence due to duration and depth. This paper presents statistical analyses of voltage sags in several domestic and industrial transformer stations. Voltage sag probability functions are calculated from actual measurement data, by means of a hill climbing algorithm. Lognormal and Weibull frequency distribution functions are used to describe distribution of measured voltage dips. %K power quality %K voltage sag %K probability functions %K chi squared criterion %K hill climbing algorithm %U http://versita.metapress.com/content/x7110847315q5426/?p=bbff6612542b46139c48c8c77dd66ecf&pi=2