Leakage Current Based Contamination Level Monitoring of High Voltage Insulators

Long-distance transfer of electrical energy can be affected by flashover of high voltage insulators in transmission system and stations, and is considered to be a significant problem. The main cause of these flashovers is the contamination in the areas such as industrial, agricultural, desert, and coastal, under non-favourable climatic conditions like dew, fog or rain. In Saudi Arabia, most of the transmission lines were built in coastal areas, which make the insulator contamination a main concern that dictates the proper design of high-voltage transmission lines. Reliability of a power system is jeopardized by flashovers due to consequent prolonged service outage. In the past, various methods were utilized to enhance the efficiency of high-voltage insulators working in polluted environments. Some of these approaches are creepage extender, increasing the number of insulator string, and regular washing of insulator; washing is being widely used, whereby the power system utilities invest significant resources. A problem that still persists in this case is the selection of optimal time span of insulator washing due to its dependence on the contamination level. Various methods were devised to observe and evaluate the extent of contamination on the insulators, such as leakage current, corona current, voltage distribution, ultrasound and ultraviolet methods. The objective of this research work is to develop a means for observing and measuring the contamination level on high-voltage insulators. A leakage current data acquisition system will be used to acquire the instantaneous leakage current signal at scheduled intervals. Signal processing and pattern recognition will be used to extract required features form the collected signals to evaluate the contamination level that would cause a flashover. This contamination level monitoring tool will provide essential information for maintenance departments in the electric utility companies to properly schedule the expensive and extensive high-pressure water live line and substation insulator washing. This will result in huge savings in maintenance costs and improves the electrical system reliability.