| Rod type suspension composite insulators have many advantages,such as light,small volume,easy installation,pollution flashover resistance and so on.It has been widely used in transmission lines.However,the material of sheds and sheath of rod type suspension composite insulators easily damaged by bird pecking,especially in recent years,the number of birds multiplied and the range of activities increased.The bird pecking caused the damage to the rod type suspension composite insulators'sheds,which seriously threatened the safety of the power grid.In order to investigate the effect of sheds damage on the electric field distribution and pollution flashover characteristics of rod type suspension composite insulators,this paper investigated the damage of rod type suspension composite insulators on the AC/DC transmission lines of five provinces,such as Henan,Hubei,Shandong,Zhejiang and Hebei.Artificial damage simulation was carried out for 35kV,110kV and 220kV rod type suspension composite insulators in the laboratory.The influence of parachute sheds damage on the AC electric field distribution and pollution flashover characteristics of rod type suspension composite insulators was studied.The main achievements of this paper are as follows:(1)The damage of sheds has a certain effect on the surface electric field distribution of rod type suspension composite insulators,and the maximum electric field intensity of insulators will increase.With the increase of damage degree,the amplitude of the maximum value of the electric field strength increasing along the surface of the insulator increases.Under the same damage area,as the number of damage increases,the amplitude of the maximum intensity along the surface electric field decreases.In addition,as the voltage level of insulator increases and the height of structure increases,the influence of sheds damage on the maximum electric field intensity of rod type suspension composite insulators decreases.The maximum electric field intensity of35kV,110kV and 220kV rod type suspension composite insulators increased by 4.19%,3.27%and 2.83%respectively,when damaged to the root.(2)The damage of sheds has great influence on the electric field distribution at the notch of rod type suspension composite insulator,which will result in the maximum electric field intensity at the notch.With the increase of damage degree,the maximum distortion amplitude of the electric field strength at the damage notch increases,and the number of damage increases under the same damage area,and the amplitude of the maximum distortion of the electric field intensity at the damage notch decreases.The maximum electric field strength of 35kV,110kV and 220kV rod type suspension composite insulators increased by 62.68%,74.27%and 68.74%respectively in the damage to the root.In addition,the maximum electric field strength at the damage notch of 35kV,110kV and 220kV rod type suspension composite insulators appeared in the tip of the damage notch in the damage area of 12%(corresponding to damage radius of28.0mm,39.2mm,50.0mm respectively).The maximum electric field intensity at the notch of the sheds is found at the damage root sheath when the damage to the root.(3)The damage of sheds leads to the decrease of pollution flashover voltage of rod type suspension composite insulators,and the amplitude of AC flashover voltage drop increases with the increase of damage degree.Under the same damage area,the amplitude of AC flashover voltage dropment decreases with the increase of damage number.In addition,with the increase of insulator voltage level and the increase of structure height,the influence of damage degree and number of damage on AC flashover voltage of rod type suspension composite insulators gradually weaken.The contamination degree of ESDD is 0.1~0.3mg/cm~2,and the maximum pollution flashover voltage of 35kV,110kV and 220kV rod type suspension composite insulators decreases by 35.92%,15.03%and 9.11%respectively in the condition of damage to the root.(4)The damage of sheds will reduce the creepage distance flashover voltage gradient E_L and the dry arc distance flashover voltage gradient E_H of rod type suspension composite insulators.With the increase of the damage degree,the amplitude of the E_L and E_H increases.Under the same damage area,as the number of damage increases,the E_L and the E_H is reduced.In addition,with the increase of insulator voltage level and structure height,the influence of damage degree and damage amount on the creepage distance flashover voltage gradient E_L and the dry arc distance flashover voltage gradient E_H gradually weaken.The contamination degree of ESDD is0.1~0.3mg/cm~2,the creepage distance flashover voltage gradient E_L of 35kV,110kV and 220kV rod type suspension composite insulators is decreased by 19.15%,6.05%,1.34%,respectively,and the dry arc distance flashover voltage gradient E_H is decreased by 35.92%,15.03%and 9.11%,respectively in the condition of damage to the root. |
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