基于有限元仿真的土壤直埋电缆中间接头稳态载流量计算

Calculation on Steady⁃state Current Carrying Capacity of Intermediate Joint of Direct Buried Cable Based on the Finite Element Simulation

在运行过程中,电力电缆中间接头的温度通常会比电缆本体高,基于电缆本体温升不超过90℃而计算得到的稳态载流量会造成中间接头的损坏。对于土壤直埋直流电缆接头,利用有限元仿真软件构建三维模型对温度和载流量计算准确度较高,同时为简化计算过程,利用二维轴对称模块建立了接头的平面结构,并旋转形成中间接头的三维模型。对土壤中电缆接头和本体的温度和稳态载流量进行仿真计算,由本体确定的载流量会使接头导体温度高于最大长期允许温度值,不利于电缆长期稳定运行。水分迁移使接头周围土壤热阻增大,采用回填沙土可在一定程度上提高中间接头的稳态载流量。

In the process of operation,the temperature of intermediate joint of power cable is usually higher than that of the cable body,and the steady⁃state current carrying capacity,which is calculated on such basis that the tempera⁃ture rise of the cable body is no more than 90℃,will cause damage to the intermediate joint.For the direct buried DC cable joint,the accuracy of temperature and current carrying capacity calculation is high by using a three⁃dimen⁃sional model which is constructed by finite element simulation software.In order to simplify the calculation process at the same time,the plane structure of the joint is set up by using the two⁃dimensional axis symmetric module,which is rotated to form a three⁃dimensional model of the intermediate joint.The temperature and steady⁃state current carry⁃ing capacity of cable joints and cable body in soil are simulated and calculated.The current carrying capacity,deter⁃mined by the cable body,will make the conductor temperature of the joints higher than the maximum long⁃term al⁃lowable temperature,which is not favourable to long⁃term and stable operation of cables.The heat resistance of the soil around the joint is increased by water migration,and the steady⁃state carrying capacity of the intermediate joint can be increased,to a certain extent,by back⁃filling sand.