电力电缆温度场仿真及在线监测系统研究

发布时间：2018-01-12 12:24

本文关键词：电力电缆温度场仿真及在线监测系统研究　出处：《重庆大学》2016年硕士论文　论文类型：学位论文

【摘要】：电力电缆的使用寿命主要决定于电缆绝缘材料的老化程度,在绝缘老化过程中,绝缘材料的温度是决定其老化速度的重要因素。载流量是电力电缆的一个基本参数,载流量计算偏高易发生电缆过载现象,造成电缆温度过高,加速老化。电缆温度过高可能提示电缆存在负荷过大或故障状态,因此,实时掌握电缆运行时的温度也将有利于其安全可靠运行。本文首先详细说明了交联聚乙烯电力电缆的结构组成,从电缆的结构上阐明电缆生热的位置及原理,为电缆温度场数值计算提供理论依据。传热有限元计算的基础是热传导、热对流、热辐射三种基本传热原理和热平衡控制方程,在此基础上,结合有限元定解条件求出温度场分布。本文利用COMSOL Multiphysics有限元分析软件建立了10kV单芯电缆四回路规范敷设电缆沟几何模型,以割线法计算稳态载流量,利用温度场计算结果来定位电缆系统的最热点。针对工程中电缆沟不规则敷设情况进行建模仿真,并与规则敷设电缆沟进行结果对比,结果显示,当电缆全部敷设于电缆沟底部时,载流量规范敷设时降幅达22%,表明电缆敷设得越密集,电缆载流量越低。对电缆中间接头的热分析结果表明良好制作的中间接头线芯温度略低于两端,温差很小;当单位长度接头电阻不大于电缆本体电阻时,接头线芯与电缆本体线芯的温差不显著,随着接触电阻的升高,接头线芯温度逐渐升高。这样,通过有限元仿真定位电缆群和电缆接头的过热位置,为温度在线监测传感器布点提供理论支持,同时,仿真计算得到电缆安全运行的表皮温度上限值,解决了无法直接监测线芯温度带来的温度阈值确定难题。建立了一套电缆沟温度在线监测系统,该系统可实时采集电缆沟内温度数据。首先,对温度传感器进行标定校准和测试,利用Zigbee与GPRS相结合的方式无线传输现场数据,通过主控芯片CC2530F256编程控制,实现通过手机接收数据温度数据功能,结合仿真得到的表皮温度上限值实现温度超限预警功能。对协调器节点和终端节点程序进行设计,实现电缆沟内以及电缆沟向远端手机的通信。设备软硬件开发完成后,对设备进行了详细的实验室模拟试验和封装论证。最终,将设备安装于重庆市子山线电缆沟,持续获得现场回传温度,表明系统工作状态良好,可以有效地监测电缆的运行状态。
[Abstract]:The service life of power cable is mainly determined by the aging degree of cable insulation material, in the process of insulation aging. The temperature of insulation material is an important factor to determine its aging speed. The carrier current is a basic parameter of power cable. The overload of cable is easy to occur when the calculation of load current is on the high side, which causes the cable temperature to be too high. Accelerated aging. Excessive cable temperature may indicate excessive load or malfunction of the cable, therefore. In this paper, the structure composition of the XLPE power cable is explained in detail, and the position and principle of the heat generation of the cable are explained from the structure of the cable. The finite element calculation of heat transfer is based on three basic heat transfer principles of heat conduction, thermal convection and thermal radiation, and the control equation of heat balance. The temperature field distribution is obtained by using finite element solution condition. In this paper, COMSOL is used to calculate the temperature distribution. Multiphysics finite element analysis software has established the geometric model of cable canonical laying of 10kV single core cable. The steady load current is calculated by Secant method, and the hot spot of cable system is located by using the temperature field calculation results. The modeling and simulation of irregular laying of cable trench in engineering is carried out. The results are compared with the results of regular cable laying. The results show that when the cable is laid at the bottom of the cable ditch, the drop of the load current standard is 22%, which indicates that the more dense the cable is. The results of thermal analysis show that the temperature of the wire core is slightly lower than that of the two ends, and the temperature difference is very small. When the resistance of unit length joint is not greater than that of cable body, the temperature difference between connector core and cable core is not significant. With the increase of contact resistance, the temperature of connector core increases gradually. Finite element simulation is used to locate the overheating position of cable group and cable connector, which provides theoretical support for temperature on-line monitoring sensor placement. At the same time, the upper limit value of skin temperature for safe operation of cable is obtained by simulation. It solves the problem of determining the temperature threshold which can not be directly monitored. A cable channel temperature on-line monitoring system is established. The system can collect the temperature data in the cable ditch in real time. First of all. The temperature sensor is calibrated and calibrated, and the field data is transmitted wirelessly by combining Zigbee and GPRS, and the control is controlled by the main control chip CC2530F256. Realize the function of receiving data temperature data through mobile phone, and realize the temperature over-limit warning function with the upper limit value of skin temperature obtained by simulation. The program of coordinator node and terminal node is designed. After the development of the hardware and software of the equipment, the detailed laboratory simulation test and packaging demonstration of the equipment are carried out. Finally, the communication between the cable ditch and the remote mobile phone is realized. The installation of the equipment in the cable trench of Zishan Line in Chongqing City shows that the system is in good working condition and can effectively monitor the running state of the cable.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TM75

【相似文献】