Determination of power quality disturbances in power systems using skewness and kurtosis coefficients

In this paper; the signals consisting of power quality disturbances is determined by using statistical methods. Five kind of power quality disturbances such as voltage swells, voltage sags, voltage with harmonics, transients and flicker which last duration of 18 periods are constituted by using MATLAB. Sampling frequency is 12.8 kHz. Skewness and kurtosis coefficients of constituted signals are calculated in local frames. Changes of skewness and kurtosis coefficients´ amplitudes determine the moment of occurrences of constituted disturbances. It is observed that only skewness or only kurtosis coefficients are not adequate for distinguishing voltage swells, voltage sags, voltage with harmonics, transients and flicker. It is concluded that in order to distinguish constituted these disturbances both of these coefficients must be taken into consideration at the same time.