10 kV配网电缆温度场和载流量计算分析

Calculation an Anlysisi of Temperature Field and Current Carrying Capacity of Cables in 10 kV Distribution Network

为确保电缆能安全、正常工作,又充分发挥电缆的输送能力,采用精确方法预计地下电缆的载流量具有重要意义。针对10kV配网常用三芯电力电缆,结合传热知识对10kV配网直埋电缆温度场进行分析,构造出载流量和热流密度间的换算关系和边界条件,建立直埋三芯电力电缆的温度场模型,对电缆温度场和载流量进行仿真计算。在此基础上,基于IEC60857给出的解析计算式进行验证分析,误差不超过0.6%,且与Q/GDW512—2010《电力电缆线路运行规程》中规定的载流量值相差不大,误差不超过4%。最后,利用建立的地下直埋电缆温度场模型,分析了影响土壤直埋电缆载流量的影响因素及各因素对载流量的影响规律,为工程实际提供参考依据。

In order to ensure the safe and normal operation of the cables and give full play to the cable transmission capacity, it is important to predict the current carrying capacity of the underground cable by using an accurate method. For the three-core cables commonly used in 10 kV distribution network, combined with the heat transfer knowledge, the temperature field of the direct-buried cables in 10 kV distribution network is analyzed, so as to construct the conversion relationship and boundary conditions between the current carrying capacity and the heat-flow density. Then the temperature field model of the direct buried three-core power cable is established, moreover the temperature field and current carrying capacity of cables are simulated. On this basis, the verification and analysisi are carried out based on the analytical calculation formula given by IEC 60857. The error does not exceed 0.6%, and it is not much different from the current-carrying value specified in Q/GDW 512-2010 "Code of Operation for Power Cable Line", with the error not exceeding 4%. Finally, using the established temperature field model of underground buried cable, the influencing factors affecting the current carrying capacity of direct buried cable and the influence law of each factor on the current carrying capacity are analyzed, which provides a reference for engineering practice.