Research On Flashover Characteristics Of Bird Droppings On Composite Insulators And Optimum Design Of Bird Shield

According to statistics,bird damage fault ranks third among transmission line faults,second only to lightning flashover fault and unidentified cause flashover fault.Insulator flashover caused by bird droppings is the main cause of bird damage faults.There are many large wading birds distributed in northern China.They have a large amount of defecation and a high viscosity of bird dung,which can easily form a long passage of bird dung in the process of falling,thus triggering the flashover of bird dung.Due to the insulation distance,bird droppings flashover mostly occurs in 110 kV and 220 kV transmission lines.On the one hand,the development process of bird droppings flashover is complex and there are many influencing factors.On the other hand,the protective effect of bird droppings and other protective measures commonly used in transmission lines is limited.Therefore,it is necessary to study the relevant mechanism of bird droppings flashover,find out the critical conditions of bird droppings flashover,and optimize the structure and size of common bird protection measures accordingly,and propose new combined bird protection measures.This paper carries out flashover test of 110 kV transmission line composite insulators based on bird dropping path and carries out relevant simulation,optimizes the structure size of the existing bird shield,puts forward the optimization scheme of protection measures of bird shield matching with snap-on insulating sheath,and provides technical support for bird protection of 110 kV transmission line.The main work of this paper is as follows:Firstly,in view of a northern area where bird droppings flashover faults frequently occur,the bird activities near transmission line corridors in this area are counted,and the living habits of common large wading birds are analyzed.At the same time,the related characteristics of bird droppings flashover faults are analyzed in terms of time and line structure characteristics at fault points.Secondly,The flashover test of 110 kV transmission line composite insulators based on dropping path of bird droppings was carried out by setting up a test platform for simulating bird droppings flashover of 110 kV transmission line composite insulators.The effects of dropping path,viscosity and conductivity of bird droppings,and the presence or absence of pressure-sharing rings on the flashover of bird droppings were studied,and the critical distances of flashover of bird droppings under various conditions were obtained.Thirdly,According to the structure size of bird droppings flashover test platform,the simulation model was built.The influence of bird droppings on the spatial electric field near the insulator was calculated by finite element software.The relationship between the length of bird droppings,the spatial position of the insulator,the change rule of the spatial electric field around the bird droppings and the effect of flashover were analyzed.Finally,Based on the test data in Chapter 3,the optimization and improvement scheme of the structure size of bird shield commonly used in 110 kV transmission lines is proposed,and the protection effect of the new type bird shield is verified.At the same time,the combined protection measures of the clip-on insulating sheath and bird shield are put forward,and the protection effect is verified by the test.