A new procedure for determination of insulators contamination in electrical distribution networks

This paper presents a novel method for determination of insulator contamination (IC) level. ICs caused some problems in electric networks. Some faults occur in electric system due to ICs. These faults sometimes log to a sudden and serious damages to the systems. So ICs reduce power quality and reliability indexes. Usually insulator washing is a solution for this problem and its events. Insulators washing have a heavy cost and if a time table for their washing time can be planned, both time and cost will be saved. In this paper average insulators contamination calculated using line current. Leakage current on insulators surface are coming together with small arcs. These arcs have high frequency component. Proposed method extracts some features from these components using Discrete Wavelet Transform (DWT) and principal component analysis (PCA). Line current data gathered for six month on a 20 kV distribution feeder with 6.4 kHz sampling rate. Results show high accuracy of this method for determining of insulators contamination.