土壤直埋110 kV电缆中间接头稳态载流量仿真研究

Simulation Study on Steady-state Current Carrying Capacity ofIntermediate Joints of Directly Buried 110 kV Cables

针对目前没有成熟的交流电缆中间接头载流量校核方法,搭建了土壤直埋110 kV电缆中间接头和电缆本体稳态载流量三维仿真模型,利用有限元对比研究环境温度、土壤导热系数和敷设深度对电缆中间接头和本体稳态载流量的影响规律。结果表明:在不同环境温度、土壤导热系数和敷设深度下,电缆中间接头载流量始终小于电缆本体载流量,土壤导热系数为0.5 W·(m·K)^(-1)、环境温度为293 K以及敷设深度为1.75 m时的中间接头载流量相较于相同条件下的本体载流量减小了10.8%。因此,如按照电缆本体载流量校核电缆载流能力,将导致中间接头主绝缘处于加速热老化状态。为确保电缆长期稳定运行,建议以本体载流量确定电缆载流时应留有一定裕度。

As there is no mature standard for checking the current carrying capacity of AC cable intermediate joints at present,a three-dimensional simulation model for the steady-state current carrying capacity of directly buried 110 kV cable intermediate joints and the cable body is established,and the influence law of ambient temperature,soil thermal conductivity and buried depth on steady-state current carrying capacity of intermediate joints is studied comparatively by finite elements.The results show that the carrying capacity of intermediate joint under different ambient temperatures,soil thermal conductivities and buried depths is always less than that of the cable body,and the carrying capacity of intermediate joint under the soil thermal conductivity of 0.5 W·(m·K)^(-1),the ambient temperature of 293 K and the buried depth of 1.75 m is 10.8%less than that of the cable body.According to the above research results,if the cable current carrying capacity is determined by that of the cable body,the major insulation of intermediate joints will be in an accelerated thermal aging state.In order to ensure the long-term stable operation of the cable,it is recommended that a certain margin should be left when the current carrying capacity is determined by the cable body.