New differential busbar characteristic based on high frequencies extracted from faulted signal during current transformer saturation

Abstract

Most given techniques tend to block the differential measurement during that portion of the cycle when a current transformer (CT) is saturated. Some other techniques bring more meaning to the breakpoint settings of the operating characteristic. The time and frequency localisation properties of continuous wavelet transform (WT) offer a viable and improved option for analysing the transient characteristics of defect signals. WT depends on high frequencies of the faulted signal produced due to CT saturation. The proposed technique is based on the windowed WT of fault-generated transients to distinguish between faults in a busbar protection zone from those outside the zone, particularly in case of an early and severe CT saturation. New differential busbar characteristic with values depending on the windowed WT of fault-generated transients has also been described. © The Institution of Engineering and Technology 2014.