| Insulator in power system transmission lines play a mechanical support and electrical insulation.The insulation performance of insulator has relation to the safe operation of the power system.The fast development of DC/ AC high voltage and EHV and UHV Transformer lines has put forward higher requirements for the external insulation of power systems.The porcelain insulator is widely used in this kind of transmission line because of its special merit.However,the flashover accidents were caused by the strong winds and dust weather,environmental pollution,fog and haze now and then,that cause immeasurable losses in the electric power system.Therefore,to effectively reduce the occurrence of pollution-induced flashover accidents,and ensure the safe operation of power system and electrical equipment,it is important to investigate the pollution accumulation characteristics of the porcelain suspension disc insulator and master the natural contamination law.In this paper,the numerical simulation method was used to study the pollution accumulation characteristics of the porcelain three umbrella insulator.Based on mechanics theories,the mechanical characteristics and the motion behavior of pollution particles near the insulator were analyzed,and the dynamic deposition condition for particles on the insulator surface based on the mechanical equilibrium and moment equilibrium were also proposed,which including the conditions of the deposited particles removed by wind.The wind tunnel test at North China Electric Power University were briefly introduced.In order to reduce the error between the simulation results and the test results in wind tunnel conditions,from the three aspects of the positive and negative charge proportion,the surface energy and the particle size distribution,the numerical simulation optimization study with a progressive form on the model of the particle deposition criterion based on energy was carried out,which called three aspects of progressive optimization research(TAPOR).The optimization model was obtained and its rationality was verified.According to these results,a surface energy optimization model was used and a study was conducted on the pollution accumulation characteristics of the three umbrella porcelain insulator under strong wind environment,to analyze the effects in 110 kV HVAC and HVDC transmission lines of individual factors and multi factors such as wind speed,particle size,and voltage type on the natural contamination characteristics of insulators.The results show that: the deposition criterion optimization model based on the energy was obtained in the TAPOR.Compared with the Wind-tunnel test results,the average relative error of the simulation results on the basis of the previous step continuous decreases(6.6%,21.5%,6.4%),respectively.And they display a more consistent changing pattern along with the change of the applied DC voltage,which confirms the rationality of the optimization model.Application of the optimization model of three umbrella porcelain insulator in strong wind,as the particle size increases,the overall surface deposit amount of pollution particles(NSDD)on the insulator surface increases under 110 kV DC voltage and 110 kV AC voltage.With the increase of wind speed,the contamination of the former decrease gradually and at a very slow rate,the latter in different particle sizes show different variation rule.However,the difference of the NSDD between the NSDD of DC voltage and AC voltage decrease gradually,and tend to be consistent.When(u,dp)? [(7)13m/s,15m/s),(20?m,30?m)],the overall surface deposit amount display a U-shaped distribution along the umbrella skirt,and the effect of DC voltage is greater than the role of the AC voltage.Otherwise,the "U-shaped" distribution disappeared gradually.The proportion of NSDDDC to NSDDAC display a trend of gradual decrease and the rate become gentle with increasing wind speed.The proportion of NSDDDC to NSDDAC increases with increasing particle size at a small wind speed of 9 m/s,but increases first and then tends to be constant when wind speed at 11 m/s,and increases first and then decreases straight when wind speed at 13 m/s,15 m/s,17 m/s,and 19m/s.In addition,the accumulation characteristics of pollution particles on the upper and lower surfaces of the insulator were also obtained. |
