Detection and processing for ±660 composite insulator abnormal discharge

Composite insulators are used greatly in±660kV DC transmission line, which influenced by external factors such as strong electric field, acid rain or mist, wire load and temperature shock, leading to the degradation of insulator, hydrophobic performance decline and mechanical strength reduction, and furthermore insulator abnormal discharge and other issues are also increasing year by year. In this paper, multi-spectral detection technology is presented firstly, containing visible light, infrared and ultraviolet detection technology. Visible light, infrared and ultraviolet detection technology each has its advantages and disadvantages, and multi-spectral method combine the three effectively, to improve the detection accuracy of composite insulator abnormal discharge obviously through the horizontal and vertical contrast. Discussions from detection principle to conditions are continued. Detecting instrument selection and configuration should be based on unit, equipment, management scope, voltage level and other actual situation, to meet the requirements of accurate detecting. Ideal detection should be carried on at clear night, while the wind speed is 0.5 m/s or less and humidity 85% or less, without electromagnetic interference or background radiation interference, focusing on the umbrella and sheath of composite insulator close to wire. Practice shows that the method can detect abnormal discharge effectively, which are more accurate than signal detection technology. For actual abnormal insulator detected, characteristics of visible image, infrared imaging and UV imaging are described, which are closely interrelated from each other. Composition analysis of surface contamination indicates the presence of water soluble ions in high concentration is primary factor in abnormal discharge. For abnormal discharge problem of composite insulators, the paper also presents a new type of DC composite insulator that uses large-floral-umbrella type, which improves electri- field distribution of insulator surface, but also improves the creepage distance. Actual operation shows that such insulators operate in good condition, without abnormal discharge situation.