架空导线径向温差对弧垂计算的影响

Effect of Radial Temperature Difference on Sag Calculation for Overhead Conductors

建立了钢芯铝绞线径向温度场分布热路模型,利用有限元分析软件对不同载流值下导线截面的温度场进行计算,并分析了径向温差产生的原因,同时设计钢芯层和表层温度分布式实验进行验证.以实验结果为依据,讨论了不同的温差造成的弧垂计算误差,以及不同档距时的弧垂计算误差.研究结果表明:架空线径向温差随着载流量的提高呈增大趋势,自然对流情况下,表面温度70℃时,钢芯温度达到73.5℃,导致弧垂的计算误差逐渐扩大;在钢芯层和表层温差一定时,档距越大,计算误差越大,而相对误差越小.

In this paper, firstly, a thermal circuit model of ACSR （Aluminium Cable with Steel Reinforcement） was established to analyze the radial temperature field distribution. Secondly, the temperature field of conductor section in different loading conditions was calculated via a finite element analysis. Th en , the causes for radial temperature gra-dient were analyzed through the simulation and were verified by the experiments of temperature distribution on the steel-reinforced layer and the surface. Finally, on the basis of experimental results, the calculation errors of different sags caused respectively by temperature difference and span difference were discussed. It is found tha t, with the im-provement of current canying capacity, the radial temperature difference increases, leading to the gradual expansion of sag ,s calculation error. For example, when the outer temperature achieves 70°C , the steel core temperature under natural convection is 73. 5°C. Moreover, it is found tha t, at a certain radial temperature difference between the steel- reinforced layer and the surface, greater span may result in larger calculation error and smaller relative error.