Study On Thermal Stress And Efficiency Of Pulse Laser Cleaning Porcelain Insulator

Transmission lines are exposed to the nature for a long time.Under the humid weather conditions such as fog and rain,the pollution layer on the insulator surface is wetted,and the insulation performance is decreased.Pollution flashover may occur,which brings great hidden danger to the operation safety of power grid.At present,there are some disadvantages in the common cleaning methods of power system,such as:manual power failure cleaning will lead to power failure,charged water flushing will have a greater risk of adjacent flashover,etc.The advantages of laser cleaning,such as no grinding,non-contact,green and environmental protection,are gradually emerging in the power system.An important standard of laser cleaning is its cleaning efficiency.In this paper,the temperature stress coupling model of porcelain insulator contamination is established to analyze the change of thermal stress on porcelain surface during cleaning.Based on the thermal tensile and compressive stability of porcelain surface,the influence of laser power,scanning speed,contamination water content and other factors on cleaning efficiency is explored.The cleaning efficiency is calculated by image recognition technology and verified by pulsed laser cleaning experiment.The final conclusions are as follows:The thermal stress is analyzed by the first principal stress.The distribution of the first principal stress changes from tensile stress to compressive stress,and reaches the maximum at the center of the spot.When the power is 25W,it can ensure the gentle cleaning under most working conditions.Through screening and comparison of the heat resistance and tensile compressive threshold under different pollution conditions,it is concluded that the high efficiency scanning speed of Si O₂ is 2000-2500mm/s,Na Cl is 2500-3000mm/s,and the pollution type C is about 3000mm/s,which provides the basis for the selection of laser experimental parameters.The temperature rise is proportional to the water content,and the appropriate amount of water can improve the cleaning efficiency.The laser experiment shows that the cleaning efficiency reaches the highest when the water content is 0.115g,which is98.2%.If the water content continues to increase,the increased adhesion will reduce the cleaning efficiency,and excessive water is not conducive to cleaning.When the pollution is Si O₂,the power is 27W,and the cleaning efficiency can reach87.4%.If the power continues to increase,the efficiency improvement is not obvious,but there is a risk of damage to the glaze surface.When the pollution is C,the lower laser power can produce high temperature,and the cleaning efficiency can reach more than 90%at 25W?30W.The scanning speed affects the cleaning efficiency in the form of build-up rate,and the appropriate build-up rate of more than 50%can ensure the speed of heat accumulation.In the cleaning of different pollutants,the temperature rise is the highest when C is attached to the surface,followed by Na Cl,and the lowest is Si O₂.Laser experiments show that the highest cleaning efficiency is 96.3%when the pollution is Si O₂ and the scanning speed is 2000mm/s;When the pollution is C,the cleaning efficiency can reach 96.4%when the scanning speed reaches 3000mm/s.