| As an important external insulation equipment in electric power system,silicone rubber composite insulators are widely used in heavily polluted outside areas to ensure the safe and reliable operation of electric power system.However,during the actual operational process,composite insulators not only have to face the contamination problems caused by environmental pollution,but also need to face the impact of corona aging from transmission lines.Contamination problems and corona aging can result in the decrease of insulation properties of composite insulators,they can also lead to more pollution flashover occur.It is urgent to study the corona aging problem of contaminated composite insulators.In this paper,corona aging electrodes and environmental simulation system were used to simulate the actual environmental conditions contaminated silicone insulators may face.Under the condition of different contamination concentration,aging time and environmental humidity,influence of three kinds of influencing factors on the flashover voltage of silicone rubber after corona aging were studied.The interaction between contamination concentration and environmental humidity and hydrophobicity recovery were also studied to investigate the effect of influencing factors on flashover voltage of contaminated silicone rubber after corona aging.The above research work explored the influence of corona aging on the flashover voltage of contaminated silicone rubber,and make a preliminary exploration for the effect of corona aging on contaminated silicone rubber.By referring to national industry standard and operating condition of composite insulators,the types and concentration of contamination and the environmental humidity were determined.According to the preliminary test results of research group,the voltage of corona aging test and aging time were also determined.Secondly,by designing a set of three-factor,three-level orthogonal table,the corona aging test of silicone rubber contaminated by different kinds of contamination was carried out.Then,by measuring the flashover voltage of aged silicone rubber and using intuitive analysis and variance analysis,the effects of various factors on the flashover voltage of aged silicone rubber were studied.The results show that the contamination concentration had no effect on the flashover voltage of silicone rubber contaminated by kaolin(with salt),but had a significant effect on diatomite(with salt)contamination and kaolin(no salt)contamination.It can also been known that aging time and environmental humidity had a significant effect on flashover voltage of silicone rubber contaminated by kaolin(with salt),diatomite(with salt)and kaolin(no salt).Finally,by combining the study of interaction between contamination concentration and environmental humidity and hydrophobicity recovery of aged silicone rubber,the influence of contamination concentration,aging time and humidity on corona aging of contaminated silicone rubber were studied,and the causes of flashover voltage change after corona aging were also investigated.The result show that the interaction between contamination concentration and humidity can cause the contamination layer scattered by electrons produced by corona discharge,and the scattered contamination layer can hinder the movement of electronic resulting in the increase of flashover voltage and hydrophobic recovery angle.It can also be known that the presence of soluble salts in the contamination not only increases the interaction between contamination and humidity,but also obscures the influence of various factors on the flashover voltage after the corona aging of silicone rubber due to its good electrical conductivity.We can also know that with the increase of environmental humidity and aging time,the silicone rubber contaminated by different types of contamination due to the adhesion of aging-generating substances and the further scattered surface contamination layer,The flashover voltage after corona aging can increase at first then decrease in different environmental conditions. |
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