对流条件下架空导线载流-温度分布热路模型构建

Construction of thermal conduction model for overhead conductor ampacity-temperature distribution under convection conditions

由于架空导线径向温差的存在,仅仅以监测得到的架空线路表层温度表征导线温度,为线路安全运行埋下隐患。为此,本文根据架空导线内部导体结构特征,借鉴热电比拟思想,提出了导线内部温度分布热路模型,并确定了分布接触热阻和分布内热源的计算方法;为验证模型精度,设计并搭建升流实验系统和风洞测温实验平台,以LGJ240/30mm^2导线为例,对自然对流条件和强制对流条件下的模型计算结果进行实验验证和分析。验证结果表明:自然对流条件下,各层导体温度的平均相对误差为4.6%,强制对流条件下各层导体温度的平均相对误差仅为1.54%;径向温差的计算精度高于IEEE标准模型。

Due to the radial temperature difference of overhead conductors, the surface temperature of the overhead lines is only used to characterize the temperature of the conductors, thus laying a hidden danger for the safe operation of the lines. For this reason, according to the characteristics of the internal conductors of overhead conductors and the idea of thermoelectricity, this paper proposes a thermal circuit model of the internal temperature distribution of the conductors, and determines the distribution contact thermal resistance and the calculation method of the internal heat sources. In order to verify the accuracy of the model, this paper designs and builds a boosting current experimental system and a wind tunnel temperature measurement experiment platform. Taking the LGJ240/30mm2 wire as an example, this paper carries out experimental verification and analysis of the model calculation results under natural convection conditions and forced convection conditions. The verification results show that under natural convection conditions, the average relative error of conductor temperature in each layer is 4. 6%, and the average relative error of conductor temperature in each layer under forced conditions is only 1. 54%; the calculation accuracy of radial temperature difference is higher than the IEEE standard model.