Study On Deformation Characteristics And Outer Insulation Discharge Characteristics Of Roof Composite Insulators In Strong Wind And Dust Environment

At present,the roof composite insulator has the advantages of good pollution resistance,strong anti-aging ability and light weight,so it is widely used in railway's power distribution systems.However,insulating skirts made of silicone rubber are soft and prone to breaking when bombarded by high-speed wind.At the same time,the roof silicone rubber composite insulator of high-speed trains are easily worn down under the action of high-speed wind and sand,so that the roughness of the surface material changes,causing the hydrophobicity to decrease.Roof insulators often suffer from electrical insulation performance degradation or even flashover faults,which affect the safe and stable operation of railway's power distribution systems.In this paper,the wind pressure distribution and deformation characteristics of the composite insulators in the strong wind and dust environment,and the electric field distribution of the insulators in the complex environment are simulated and analyzed.The hydrophobicity and flashover characteristics of the silicone rubber materials under different roughness are investigated through experiments.The research results provide reference value for the optimal design of the roof insulator and improve the operation reliability of motor vehicles.The main contents of the paper are as follows:(1)Aiming at the stress and deformation characteristics of roof insulator umbrella skirt under strong wind and dust conditions,the fluid-structure interaction(FSI)method is used to calculate the wind pressure distribution on the surface of roof insulator,and the effects of wind speed and inflow angle on the stress and deformation characteristics of roof insulator are discussed.Results show the wind pressure difference between the positive and negative wind pressure zone produces a larger resultant force acting on the umbrella skirt,resulting in deformation of the umbrella skirt.The greater the wind pressure difference on the skirt surface,the greater the deformation of the umbrella skirt.The stress concentration phenomenon appears at the root of umbrella skirt.The life at the root of the umbrella skirt is obviously lower than that of the other part of the umbrella skirt under the action of repeated external force.Under different wind angles,the shape variables of umbrella skirt edges are obviously different.At the same time,the structure,angel of sheds and diameter of the umbrella skirt significantly affect the wind-resistant performance of the insulators at the same time.(2)The model of roof composite insulator is established to study the electric field distribution of insulators under three conditions: internal gap,skirt icing and cumulative rain.The simulation results show that the spatial electric field distortion of insulators is obvious when there is a internal gap at the junction of the sheath and the mandrel.With the increase of gap thickness,the maximum electric field intensity of the internal gap increases,and the larger the gap length,the smaller the distortion degree of the internal gap field strength.Under the conditions of rain and ice,the electric field distortion of insulators is obvious.(3)To study how the flashover voltage of silicone rubber depends on surface roughness,samples of silicone rubber of varying surface roughness were prepared to explore the relationship between surface roughness and the hydrophobicity of silicone rubber.In addition,we investigate the surface-flashover voltage of these samples as a function of surface roughness.The results show that an increase in surface roughness leads to a decrease in the hydrophobicity of silicone rubber.The dry-flashover voltage for samples with high surface roughness increases with increasing surface roughness,and the wetflashover voltage decreases with increasing surface roughness.In addition,with a single water droplet attached to the surface,the flashover voltage of silicone rubber increases as the surface roughness increases.Numerical simulations show that the electric field becomes more distorted with increasing surface roughness.Furthermore,the dryflashover voltage depends on the surface roughness and electric-field distortion,and the flashover characteristics of silicone rubber attached a single water droplet depend mainly on the length of the water droplet prior to flashover.