【作者】 杨帆；

【导师】 朱宁西； 刘刚；

【作者基本信息】 华南理工大学 ， 电工理论与新技术， 2019， 硕士

【摘要】 随着高压电缆在城市电网中的广泛应用,以及电力相关部门对已存在的电力电缆资产利用率和可靠性重视程度提高,如何更加准确地确定电缆线路的温度场分布和载流量,成为了近十年来高压电缆领域的热点,本文针对电缆线路载流量中尚未解决的关键研究点展开深入研究与分析,主要研究如下:1)建立三维热网络和三维有限元实时动态载流量稳态与暂态评估模型,考虑电缆本体轴向传热与皱纹铝护套轧纹结构,确定绕包与皱纹铝护套间的辐射热流量,搭建110kV高压电缆升流平台,并将四种方法(IEC标准、二维热路、三维热网络与三维有限元)获取的结果与实验结果进行对比,结果显示三维模型在计算精度上具有较大优势。2)研究高压电缆表皮温度分布规律,提出电缆表皮基于状态方程形式的轴向热路模型,建立电缆表皮三维有限元模型(ANSYS),研究电缆表皮在稳态与暂态情况下轴向路径、切面圆周路径与面区域的温度分布规律(温度范围、最大温度、温度极值等参数),并基于获取的规律提出合理的测温方案。3)确定电缆护套环流更为精确的计算模型,在感应电流的基础上考虑泄漏电流的作用,分析不同敷设环境下,正常载流与金属护套多点接地下的环流模型及其参数计算方法,运用ATP-EMTP中带集中电阻的分布参数线路模型验证了理论模型的准确性。4)提出电缆接头内压接式连接器连接电阻的数值计算模型,按标准制作五种不同截面的压接式连接器(120/150/240/500和630mm~2),利用四种不同的电接触模型结合有限元法分别建立数值计算方案(经验公式/Hertz/Greenwood/Bahrami),借助交流电阻测试平台开展上述数值模型的验证性实验,结果表明基于不规则粗糙表面弹塑性接触模型(Bahrami)的数值计算方案具有较高精度(相对误差小于3.95%)。5)搭建110kV插拔式GIS终端升流实验平台,实验发现GIS终端轴向传热明显,且温度至高点位置为弹簧顶推径向截面处的电缆导体,当加载负荷1200A时(环境29℃),GIS终端内导体最高温度为93.0℃,比电缆本体平均温度高15.4℃,已超过电缆线路的额定载流量。更多还原

【Abstract】 With the wide application of high-voltage cables in urban power grids and the increasing emphasis on the utilization and reliability of existing power cable assets by power-related departments,how to more accurately determine the temperature field distribution and ampacity of cable lines has become a hotspot in the field of cables in the past decade.This paper aims to solve some unresolved key technologies for 110 kV cable line ampacity.The main research is as follows:1)Establish a 3D(three-dimensional)thermal network and 3D finite element dynamic ampacity model,consider the axial heat transfer of the cable and the corrugated aluminum sheath structure,determine the radiant heat between the wrapped and the sheath,build 110 kV cable upflow experimental platform,and use the four methods(IEC standard,2D(twodimensional)thermal circuit,3D thermal network and 3D finite element)to obtain the results and the experimental results,the results show that the 3D model has a better accuracy.2)Research the temperature distribution law of the cable skin,propose the axial thermal circuit model of cable skin based on state equation,establish its 3D finite element model(by ANSYS),study the axial path of cable skin in steady and transient state.The axial path of the cable skin,the circumferential path of the section and the temperature distribution of the surface area(temperature range,maximum temperature,temperature extreme value,etc.)are studied,and a reasonable temperature measurement scheme is proposed based on the acquired laws.3)Determine the more accurate calculation model of the cable sheath’s current,consider the effect of leakage current on the basis of induced current,propose the current model and its parameter calculation method under normal and sheath multipoint grounding.The accuracy of the theoretical model is verified by the distributed parameter line model with concentrated resistance in ATP-EMTP.4)A numerical calculation model for the connection resistance of the compression connector in cable joint is proposed.Five different compression connectors(120/150/240/500 and 630mm2)are fabricated according to the standard,and four different electrical contact models are combined.The finite element method is used to establish a numerical calculation scheme(empirical formula/Hertz/Greenwood/Bahrami).The verification experiment of the above numerical model is carried out by the AC(alternating current)resistance test platform.The results show that the numerical calculation model based on the elastoplastic contact model of irregular rough surface(Bahrami)has a better accuracy(relative error less than 3.95%).5)Set up a 110 kV plug-in GIS terminal up-flow experimental platform.The experiment found that the axial heat transfer of the GIS terminal is obvious,and the temperature to the high point is the cable conductor at the radial pushing section of the spring.When the load is 1200A(environment 29°C)The maximum temperature of the inner conductor of the GIS terminal is 93.0°C,which is 15.4°C higher than the average temperature of the cable,and has exceeded the ampacity of the cable line.更多还原