Performance Analysis of Skewness Methods for Asymmetry Detection in High Impedance Faults

Skewness can be used to identify the asymmetry introduced into a current stream by a High Impedance Fault (HIF). This letter introduces relative skewness as a superior computational approach for detecting HIF induced asymmetry changes in the feeder current. Relative skewness is defined as a measure of asymmetry in the stream with respect to the stream itself. The key highlight is the analysis of four different methods for detecting HIF induced asymmetry changes for HIF currents as low as 0.5 Amps. The work confirms Pearson's moment coefficient of skewness as the most efficient method in producing the highest asymmetry separability in the post fault average skewness. The letter concludes by proposing a technique in discriminating HIF induced skewness changes from those by other likely disturbances.