Study On Wind-induced Response Simulation And Monitoring Methods Of Overhead Transmission Line Tower-line System

With the rapid social and economic development of China in recent years,the pressure of electric power supply has increased dramatically.In order to ensure the transmission of electric power,the scale of overhead transmission line construction has also increased substantially.In the process of further expanding the coverage of power grids,the operation,maintenance and management of overhead transmission lines are becoming more and more difficult,and especially the wind damage and other factors have greatly endangered the security of transmission lines.As the carrier for electric power transmission,the transmission lines constitute the continuous system composed of conductors,tower and foundation,as a complex spatial coupling system.The interaction between wind and iron tower and conductors is a typical issue about fluid(wind)and solid(tower and conductor)coupling.Under the action of fluctuating wind,the vibration of conductors will produce varying tension,and the dynamic tension,when transmitted to the transmission line tower,will generate vibration and displacement and superimpose with the vibration and displacement of the tower under the action of wind load.Furthermore,the movement of the tower will have the suspension point of the conductor displaced and then further change the tension in the conductor.In the current structure design,the conductor,the tower and the foundation are usually taken as independent units for stress analysis,which is different from the actual line stress.Especially for tower multi-circuit lines,long-span lines and UHV lines,the tower line coupling vibration caused by wind load should be quantitatively evaluated to further clarify the influence of tower-line coupling effect.In this thesis,systematic study is conducted based on the numerical simulation and the research and development of the wind-induced vibration characteristic measuring devices in the in-transit lines.The basic principle of numerical simulation of wind-induced vibration response analysis of transmission tower line system is proposed in this thesis.By ignoring the flexural rigidity and torsional rigidity of conductors and ground wires,linear bar elements are used to simulate conductors and ground wires in finite element simulation and complete the form finding of conductors and ground wires under initial tension and dead weight.The time history of velocity for fluctuating wind is generated by using the method of spectrum reproduction,and the target spectrum is Davenport wind spectrum.The expression of fluctuating wind is derived,and the wind load curves applied on conductors,ground wires and towers in the typical section lines are further determined.During the finite element modeling of the tower-line system,the main materials of the tower are simulated by BEAM4 element with the diagonal and auxiliary materials simulated by LINK8 element,and the insulator simulated by LINK8 element.The wind load is applied to the corresponding nodes of the tower,conductors and ground wires through the equivalent concentrated force.The idea of using the Newmark method to solve the dynamic response of the nonlinear finite element numerical model of the tower line system is proposed.Taking a section of 220 k V double-circuit transmission line on the same tower as an example,this thesis establishes a finite element model for 3D tower line system which includes tower,conductors,ground wires and insulator.In the course,the wind-induced action under the design wind velocity is fully considered.The dynamic characteristics and wind-induced vibration response of the coupling system between tower and lines under the conditions of static wind action and the combination of static wind and fluctuating wind are carefully analyzed.The influence of the coupling effect between tower and lines on the load-carrying properties of the tower is studied.It is found that compared with the static wind load in the design code,the amplitude and tension of conductors and ground wires are significantly increased under the action of fluctuating wind.The reason for the difference between the wind-induced dynamic response of transmission tower line system model and the tower stress of single tower model is that when only the wind load of the line is calculated,the centroid heights of the left and right lines are assumed to the same.In the coupling model of tower and lines,the centroid heights of both lateral lines should be considered according to the local situation.According to the analysis result of wind-induced vibration response of transmission tower-line system,the technical scheme of wind-induced response monitoring device for tower line system is proposed,and the parameter requirements of the monitoring device are specified,the design scheme of micro-integrated intelligent monitoring device for vibration,wind velocity and temperature is prepared based on hardware and software,and the prototype development and performance test of the monitoring device are carried out.The results show that the wind-induced vibration monitoring device designed in this thesis has resolved the multi-parameter integrated monitoring technology of environmental wind field,conductor vibration and conductor temperature,featuring ultra-low power consumption,high reliability and edge warning.This will provide an important support for the wind-induced vibration monitoring of transmission lines and the safety of line operation.The research result of this project is of important theoretical value and practical significance for resisting the destructive power of wind load and ensuring the safe and reliable power supply of lines,therefore,it is of profound practicability.