Research On Wind Deflection Characteristics And Structural Optimization Of Y-shaped Insulator Strings In High Voltage Transmission Lines

Insulator strings are one of the important components in high-voltage transmission lines.Insulator strings can experience wind deflection in strong wind weather.When the wind deflection angle of the insulator strings is too large,wind deflection flashover can occur,which is a major safety hazard for the normal operation of transmission lines.There are three types of insulator string structures in transmission lines: I-type string,V-type string,and Y-type string.Under high wind speeds,the wind deflection angle of I-string is too large,the angle between V-string structures is large,the cross arm is long,and the economy is poor.The Y-string combines the advantages of I-string and V-string to reduce the risk of wind deflection on transmission lines,and the economy is better.Studying the wind deflection characteristics of Y-shaped insulator strings is of great significance for the safety and economic construction of transmission lines.Wind load is the main reason that affects the wind deviation of insulator strings.Wind load calculation includes steady-state wind load calculation and pulsating wind load calculation.This article deduces and compares the two wind load calculation methods.The pulsating wind load calculation will be greater than the steady-state wind load,about 1.5 times,indicating that the current wind load design value is low,which is one of the reasons for frequent wind deviation accidents on transmission lines;Divide the Y-shaped insulator string into three parts: left and right legs,and section I for wind deflection theory derivation.Use the unloading angle to describe the stress state and stability of the insulator string.The larger the unloading angle,the easier it is for the insulator string to lose stability.It is recommended that the unloading angle generally not exceed 10 °.The corresponding finite element model is established through finite element software,different working conditions are set and finite Metacomputing is carried out,and the stress on the left and right legs of the insulator string and the angular displacement of section I are obtained;According to the calculation method of fluctuating wind load,the mathematical software is used to simulate the fluctuating wind time history for finite element calculation.Compared with the steady wind results,the fluctuating wind amplification coefficient is about 1.4;The buckling analysis of the leeward limb of composite insulator strings shows that the leeward limb still bears a certain pressure after buckling.Based on this characteristic,Y-shaped insulator strings can have a certain unloading angle,indicating that the current specifications have a relatively conservative design for the included angle of insulator strings.Conduct analysis and research on the current design methods of Y-type insulator strings,optimize the size and structure of Y-type insulator strings,reasonably select the length of section I and the angle between the two legs,shorten the distance between the cross arm hanging points of the insulator string,control the unloading angle of the insulator string,and improve the design economy of transmission line towers.According to the calculation results of the example,the distance between the cross arm hanging points can be reduced by about 30%;The design scheme of pressure bearing insulator string is proposed.The connection form of fittings and insulator string leeward leg is changed from hinged connection to fixed connection,and its pressure bearing capacity is greatly improved.According to the results of finite element calculation,the connection form of fittings and sub strings is better than hinged connection,which is conducive to reducing the occurrence of wind deflection flashover of transmission lines.Conduct simulation experiments on wind deflection of insulator strings by building a real model of Y-shaped insulator strings.The corresponding experimental scheme is designed,and different load conditions are applied to make the insulator string in four states of windage deviation process: catenary state under gravity,straight state under vertical load of conductor,windage deviation state under horizontal wind load,and critical state where leeward leg is not stressed.The coordinates of each point of the insulator string are observed under these four states,and the stress laws of both legs of the insulator string are calculated and compared with the finite element results,Verified the correctness of finite element simulation and proposed design reference suggestions for the application of insulator string engineering.