Simulation Study On Contamination Depositing Characteristics Of Electrified Railway Catenary Insulators

In electrified railway catenary,catenary wrist arm supporting insulator is one of the most widely used high voltage insulation device,under the working condition,both ends of catenary insulator is withstanding 27.5 KV single-phase alternating current(ac),and also bear the tension of catenary suspension mechanical load,so the reliability of the insulator of the electrified railway traction power supply system has a vital role.In recent years,with the rapid increase of industry level,air pollution is increasingly serious,fog particle concentration in the air is also on the rise.Under the natural wind,dust particles will gradually accumulated in the insulator surface,when the insulator’s environment is humid,insulation performance of insulators will decrease,it will cause partial discharge of insulators,serious insulator pollution flashover event happens,it will do great harm to the normal work of the whole electrification railway.When the insulator pollution flashover occurs,equivalent to a short circuit.Substation tripping caused power outages,affect the normal operation of railway transportation system.Therefore,the research of catenary insulator pollution characteristics,master the law of pollution accumulation in natural conditions,can provide theoretical guidance for cleaning of catenary insulator,so that it can be less catenary insulator pollution flashover accidents,to ensure normal power of catenary and normal operation of railway transportation system.In this paper,COMSOL Multiphysics multi-physical field simulation software is used to simulate the natural contamination of catenary insulators.Firstly,the force of dust particles in contact with the surface of catenary insulators is analyzed.Based on the principles of mechanical balance and energy conservation,the theoretical criteria for the adhesion of dust particles to the surface of insulators are given.Then,based on the criterion of energy conservation,it is used as a program input simulation software to analyze the contact insulators in AC and non-electrified systems.Under the circumstances,with the change of wind speed and particle size,change of contamination depositing Characteristics of Insulators.The research results show that in a certain range of dust particle size,with the increase of dust particle size,the influence of wind speed on insulator fouling gradually weakens,and the amount of surface contamination on insulator no longer increases with the increase of wind speed,and finally tends to saturation;when the particle size is larger,the amount of surface contamination on insulator is no longer increasing with the increase of wind speed,But when the wind speed is in a certain range,the amount of contamination on insulators decreases firstly,and then increases with the increase of wind speed;when the particles are not charged,the amount of contamination on insulators has the same trend with the change of wind speed under AC electric field,and the curves of the two changes coincide basically,and the amount of contamination on insulators surface varies little;the amount of contamination on insulators surface varies largely with the particle size of dust particles.When the wind speed is small,the amount of contamination on the insulator surface increases rapidly with the increase of particle size.When the wind speed is large,the growth rate becomes gentler.When the wind speed is larger,the amount of contamination on the insulator surface will decrease locally with the increase of particle size.Trend.At low wind speed,the contamination of umbrella skirts at both ends of insulators is higher.The contamination of high-voltage insulators is more serious than that of low-voltage insulators.The contamination of umbrella skirts in the middle of insulators is smaller.The contamination distribution of umbrella skirts of insulators is generally U-shaped.When the wind speed increases,the contamination of insulators at highvoltage ends will gradually decrease,and the contamination accumulation of insulators at high-voltage terminals will eventually be lower than that of insulators at low-voltage terminals.The contamination of the insulator at the pressure end is serious;moreover,with the increase of dust particle size,this "U" type distribution will become no longer significant,and the volume of each umbrella skirt of insulator will become average;in the case of low wind speed,the contamination on the upper surface of No.1 umbrella skirt near the low voltage end is the largest,and the contamination on the upper surface of other umbrella skirts is quite different from that of No.1 umbrella skirt.With the increase of wind speed,the amount of contamination on the top surface of No.1 umbrella skirt decreased,and the difference between the amounts of contamination on the top surface of other umbrella skirts decreased gradually.Finally,the amount of contamination on the top surface of each umbrella skirt became average.The amount of contamination on the surface of insulator umbrella skirt No.9 near the high voltage end does not change much under different wind speed conditions,and the amount of contamination on the surface of insulator umbrella skirt No.5 at the middle position increases with the wind speed.Under this condition,the amount of pollution accumulated on the upper surface of the umbrella skirt is slightly larger than that on other umbrella skirts.Under the action of AC,the distribution of pollution accumulated on the lower surface of the umbrella skirt is no longer U-shaped.With the increase of wind speed,the regularity of contamination on the undersurface of each umbrella skirt of insulators is very similar,and the contamination on the undersurface of No.9 umbrella skirt is the highest at the high voltage end;when the wind speed is less than 6m/s,the contamination on the undersurface of No.9 umbrella skirt will increase with the increase of wind speed,but after the increase of wind speed to 8m/s,the contamination on the undersurface of No.9 umbrella skirt will decrease again,so we can Small wind speed is more conducive to the deposition of particles on the lower surface of insulators under the action of AC electric field;when the particle size is 10μm,it can be seen that the amount of contamination on the upper surface of catenary insulator umbrella skirt is 2-6 times that on the lower surface,and the amount of contamination on the upper surface of umbrella skirt decreases with the increase of wind speed,while the amount of contamination on the lower surface of umbrella skirt remains basically unchanged with the increase of wind speed.When the particle size of dust is 20μm,the amount of contamination on the upper and lower surfaces of catenary insulator umbrella skirt decreases with the increase of wind speed,and the difference between the amount of contamination on the upper and lower surfaces of umbrella skirt is very small.In the case of small wind speed,the amount of contamination on the lower surface of umbrella skirt is obviously larger than that on the upper surface,but with the increase of wind speed,the amount of contamination on the upper surface of umbrella skirt will exceed that on the When the size of dust particles is 30μm,the amount of fouling on the lower surface of umbrella skirt is larger than that on the upper surface of umbrella skirt,and the difference between them continues to increase with the increase of wind speed.The amount of fouling on the lower surface of umbrella skirt increases with the increase of wind speed,but the amount of fouling on the upper surface of umbrella skirt first increases and then decreases with the increase of wind speed.Under the action of AC electric field,the smaller particles are more favorable to deposit on the surface of umbrella skirt under the condition of small wind speed,while the larger particles are more favorable to deposit on the surface of umbrella skirt under the condition of large wind speed.