| The internal transmission temperature of the overhead transmission line will be changed during the operation due to the load flow.At the same time,due to the existence of tension,the fatigue life of the transmission line will be different from the normal temperature.At present,the existing literature generally takes the average stress of the whole wire under normal temperature condition when calculating the fatigue life of the transmission line.However,the material of each layer inside the steel core aluminum strand is different,and the axial tension of the inner layers is also different.Stress changes are more complicated when the temperature is affected by the temperature change.Therefore,it is necessary to calculate the stress of each layer of the transmission wire at the operating temperature to more accurately calculate the fatigue life of the breeze vibration.Aiming at this problem,this paper studies the mechanical properties of the wire under normal temperature and power-on temperature and its influence on fatigue life.The main work is:Firstly,the stress of transmission line at room temperature is studied,and the cross-section stress is obtained by theoretical calculation.The fine solid model of the wire is established by ANSYS Workbench.The simulation results are compared with the calculation results,and the accuracy of the calculation formula is verified.Secondly,according to the characteristics of stratified stress,synergistic deformation and linear expansion deformation of transmission wires,combined with the stratified stress formula of the second section and the basic formula of temperature stress,the layered stress of the transmission line section under temperature is derived.The three-dimensional solid model established in the second chapter is used to simulate the tensile stress and temperature field,and the results are compared with the calculated results.The results show that the calculation formula established in this paper is applicable to the radial temperature difference of the section isothermal section.Finally,the mechanism of the breeze vibration of overhead transmission lines and the method of predicting the fatigue life of the conductors are introduced in detail.Through the Goodman model,the derivation formula is used to solve the equivalent alternating stress,and the fatigue life of the transmission line is evaluated by combining wind speed and wind direction probability distribution,S-N curve and linear fatigue cumulative damage theory. |
