Study On Dynamic Behavior Characteristics Of Particle On Insulator Surface Under Strong Electric Field

Pollution flashover of transmission lines is one of the disastrous accidents that endanger the safety of power system.As an important medium to cause pollution flashover accidents,it is of great significance to study the physical and chemical characteristics of contamination particles deposited on insulators.Especially with the frequent occurrence of haze weather typically represented by small particle size PM2.5 and PM10,whether the particle size distribution characteristics of deposition particles on insulator surface will change accordingly,and the impact on pollution flashover characteristics is worthy of further research.In this paper,several groups of insulator surface contamination samples were obtained by artificial natural contamination test and transportation line contamination test.The micro-morphology and particle size distribution characteristics of insulators were studied by scanning electron microscopy and laser particle size analyzer.The results show that the particle size distribution of the deposition particles on the insulator surface obeys the lognormal distribution approximately,and the particle size distribution mainly concentrates on 20?m while the particles with a particle size of ?5?m or ?50?m have a lower distribution probability.In order to explore the formation mechanism of the particle size distribution characteristics,a collision deposition dynamic model of particulate matter on the insulator surface was established based on computational fluid dynamics,aerodynamics and contact mechanics.The numerical simulation of the particle deposition process was carried out,and the effects of different factors on the particle size distribution of the deposition particles on the surface of ceramic and composite insulators were analyzed.The results show that the relative humidity and air velocity have significant effects on the particle size distribution of the deposition particles on the surface of ceramic insulators,while the electric field type,electric field strength and aerodynamic shape have relatively weak effects on the particle size distribution of the deposition particles,which are mainly reflected in the number of deposition particles.On the surface of composite insulators,relative humidity,air velocity,and charge accumulation have a significant effect on the particle size distribution of the deposition particles.The electric field type and electric field strength have a relatively weak influence on the particle size distribution of the deposition particles.Because of the corrugated groove structure of the ceramic insulator umbrella skirt,the particle size distribution characteristics of the upper and lower surfaces are obviously different,while the composite insulator streamlined umbrella skirt structure,the particle size distribution characteristics of the upper and lower surfaces are similar.In addition,the particles with particle size ?15?m and ?80?m are weakly affected by the correlation parameters,while the particles with the particle size of 20?m~80?m are highly susceptible to the correlation parameters,resulting in significant changes in the particle size distribution structure.Specifically,the greater the relative humidity,the easier the insulator surface to deposit to large particle size,and the more the number of deposition.At low wind speed(v?6m/s),the number of deposition particles and the range of main particle size distribution showed a significant downward trend with the increase of wind speed,while at high wind speed(v?6m/s),the number of deposition particles and the range of main particle size distribution showed a gradual downward trend with the increase of wind speed,and showed saturation.The influence of electric field type and electric field strength on the deposition particles is mainly reflected in the amount of deposition,and has no significant effect on the particle size distribution characteristics,and the peak distribution of the distribution is around 30?m.The influence of aerodynamic shape on the deposition particles is mainly caused by the longitudinal cross-section area and the structure of the lower surface umbrella skirt,which results in the difference of the size distribution characteristics of the lower surface.The charge accumulation causes distortion of the electric field distribution,which in turn promotes deposition of large particle size particles(40?m~90?m).In general,for the typical haze particles(PM2.5 and PM10)in fog and haze weather,the deposition on the insulator surface is weakly affected by the related parameters,and the deposition proportion is relatively small,which cannot have a fundamental impact on the physical and chemical properties of the insulator deposition particles.But the fog,a high humidity condition,will effectively promote the amount of contamination on the surface of insulators.