Abstract
Anti-pollution flashover of insulator is important for power systems. In recent years, haze-fog weather occurs frequently, which makes discharge occurs easily on the insulator surface and accelerates insulation aging of insulator. In order to study the influence of haze-fog on the surface discharge of room temperature vulcanized silicone rubber, an artificial haze-fog lab was established. Based on four consecutive years of insulator contamination accumulation and atmospheric sampling in haze-fog environment, the contamination configuration appropriate for RTV-coated surface discharge test under simulation environment of haze-fog was put forward. ANSYS Maxwell was used to analyze the influence of room temperature vulcanized silicone rubber surface attachments on electric field distribution. The changes of droplet on the polluted room temperature vulcanized silicone rubber surface and the corresponding surface flashover voltage under alternating current (AC), direct current (DC) positive polar (+), and DC negative polar (−) power source were recorded by a high speed camera. The results are as follows: The main ion components from haze-fog atmospheric particles are NO3−, SO42−, NH4+, and Ca2+. In haze-fog environment, both the equivalent salt deposit density (ESDD) and non-soluble deposit density (NSDD) of insulators are higher than that under general environment. The amount of large particles on the AC transmission line is greater than that of the DC transmission line. The influence of DC polarity power source on the distribution of contamination particle size is not significant. After the deposition of haze-fog, the local conductivity of the room temperature vulcanized silicone rubber surface increased, which caused the flashover voltage reduce. Discharge is liable to occur at the triple junction point of droplet, air, and room temperature vulcanized silicone rubber surface. After the deformation or movement of droplets, a new triple junction point would be formed, which would seriously reduce the dielectric strength of room temperature vulcanized silicone rubber.
Highlights
Insulator flashover accident is one of the important influencing factors to the safety and stability of power grid
By a high speed camera, the changes of the droplet attached on the surface of contaminated silicone rubber and the corresponding flashover voltage were recorded in alternating current (AC) field and positive polarity direct current (DC) field, respectively
The rated and the particles are irregular in shape, in order to better simulate the contamination characteristics capacity, rated current, and output voltage of DC high voltage source is 1.2 kVA, 10 mA, and 0–120 kV, in haze-fog environment, SiO2 is proposed to replace kieselguhr for simulating the non-soluble deposit density (NSDD) with respectively
Summary
Insulator flashover accident is one of the important influencing factors to the safety and stability of power grid. The occurrence of flashover under haze-fog environment is related with insulator pollution degree, haze component, haze particle size, fog-water conductivity, and so on. It is even more complicated than other pollution flashover [4,5,6,7,8]. The flashover performance of silicone rubber surface under haze-fog environment needs to be studied in further. By a high speed camera, the changes of the droplet attached on the surface of contaminated silicone rubber and the corresponding flashover voltage were recorded in AC field and positive (negative) polarity DC field, respectively. The research results may provide a reference for the study of the surface discharge characteristics of silicone rubber in haze-fog environment
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