Feature extraction and classification of surface discharges on an ice-covered insulator string during AC flashover using gray-level co-occurrence matrix

Abstract

This study focuses on the feature extraction and classification of surface discharges of ice-covered insulator strings during process of alternating current flashover. The test specimen was the five units suspension ceramic insulators, which was artificially accreted with wet-grown ice in the cold-climate room of CIGELE. Based on the IEEE Standard 1783/2009, flashover experiments were conducted on iced insulators to measure the minimum flashover voltage (VMF) and record the propagating process of surface discharges to flashover by using a high-speed video camera. The gray-level co-occurrence matrix (GLCM) method has been used to extract four parameters of arc discharge images features that characterize different stages of flashover process. The parameters are angular second moment (ASM), contrast (CON), inverse difference moment (IDM) and entropy (ENT). These statistical parameters of GLCM can be extracted to reveal the underlying properties of ice flashover on the insulator surface from the quantitative perspective. The different values of these indicators are representative of the different stages in the process of arc discharge. Once the value of quantitative indicators (ASM, CON, IDM, ENT) of surface discharges exceeds the threshold value, the higher flashover risk of iced insulators will appear. Hence, the proposed methods are helpful to understand and monitor surface discharge on iced outdoor insulator strings for preventing flashover accidents.

Leakage current characteristics in estimating insulator reliability: experimental investigation and analysis

“…Accordingly, it is important to observe different environmental factors, including the type of materials, dampness, and pollutants, that have a considerable influence on the efficiency and health of the high voltage transmission lines insulators that can directly affect the performance of the transmission systems. For example, pollution deposition on the surface of the insulators results in the insulators being subject to a leakage current (LC) flux which leads to extensive discharge activity on the insulators' surface [1][2][3][4][5][6] . As a result, these discharge activities can escalate and generate a flashover occurrence, which might cause an electrical grid outage or even breakdown [7][8][9] .…”

“…It should be noted that testing the insulators in actual sites differs from typical experimental test setups. Recent studies [43][44][45] show that synthetic accelerated tests are used in experimental settings to study flashover states of contaminated insulators. It should www.nature.com/scientificreports/ be highlighted that all these studies are based on the standard process for insulator tests 35 .…”

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“…Contrast was directly proportional to texture grooves; the larger the value of the groove, the clearer the image. On the contrary, the smaller the value of the groove, the smaller the image contrast and the more blurred the image [ 22 ]. GLN measured the similarity of the gray-level intensity values in the ROI.…”