计及护套环流和电流分布的多回电缆线路温度场及载流量研究

发布时间：2018-05-04 07:40

本文选题：多回电缆线路 + 同相多根并联　；参考：《重庆大学》2014年硕士论文

【摘要】：受到城市地形、地下空间限制，，为了满足大中城市电力供应越来越多采用多回电缆线路同相多根并联运行。但是，对于多回电缆线路同相多根并联运行参数的计算，现有的设计规程、规范不再适用。而目前对于多回电缆线路同相多根并联运行的设计、施工并无相关规程、规范。并且，以往研究中常常将多回电缆线路同相多根并联的护套环流、同相并联多根电缆的电流分布的不均匀与温度场及载流量计算完全独立成不相关的领域，大部分文献中仅仅涉及到其中之一，而不是将其联系起来组成系统工程进行研究。与此同时，在传统的多回电缆线路温度场及载流量计算中，各参数的取值一般均采用IEC-60287标准中的推荐值，而这与工程实际中电缆线路运行参数存在明显差异，导致电缆线路载流量的理论值与实际值不符。本文打破以往惯用思路，尝试建立了计及护套环流和电流分布的多回电缆线路同相多根并联的温度场计算的精细化模型，并结合220kV坪江线等六回线路工程实际情况进行研究。本文取得的主要成果如下： ①首先，将电力电缆分别按照绝缘材料、电压等级、结构特征、敷设条件等指标加以分类。并以截面积2000mm2的YJLW02-127/220kV交联聚乙烯电缆为例，对其基本结构进行阐述。然后，详细介绍了电缆线路四种常用敷设方式，即直埋敷设、排管敷设、电缆沟敷设和隧道敷设各自优缺点及适用范围。最后，建立了涵盖可靠性、经济型、可监测性、载流量等指标的敷设方式选择评价体系。 ②建立了多回电缆线路护套环流、同相并联电缆电流分布的等值计算模型，推导了多回电缆线路同相多根并联时护套环流、同相并联电缆的电流分布计算方法，并编程求解。结合220kV坪江线等六回线路工程实际，建模计算了其在两种不同排列方式下电缆线路按照四种相序排列加载电流时1~24号电缆护套环流、同相并联两根电缆的电流分布，并进行了对比研究。为建立计及护套环流和电流分布的220kV坪江线等六回线路温度场计算的精细化模型打下基础。 ③根据220kV坪江线等六回线路的具体参数以及敷设方式，首先分段建立了其温度场计算的截面物理模型；紧接着，根据传热学原理建立了电缆群及其周围敷设区域内的稳态导热微分方程，并结合②中内容分别对初始条件、内部热源损耗值以及各热力学参数进行计算和取值，从而建立计及护套环流和电流分布的220kV坪江线等六回线路温度场计算的精细化模型。将求解区域用三角形网格进行自动划分并对稳态导热微分方程进行求解，得到在100%额定负荷电流和120%额定负荷电流下电缆群及其周围敷设区域的温度分布；最后，利用双点弦截法对各分段电缆线路的载流量进行计算和分析。 ④针对目前地下电缆线路的敷设条件和外界环境等情况日益复杂的现状，以电缆沟敷设下220kV坪江一线和二线为例进行仿真计算，分析了电缆线路的敷设条件如电缆沟深度、电缆层间距等以及外界环境因素如空气温度、土壤热阻系数等的因素的变化对220kV坪江一线和二线同相并联两根电缆载流量的影响，并进行规律性总结。
[Abstract]:In order to meet the demand of urban terrain and underground space limitation , in order to meet the increasing power supply of large and medium - sized cities , many parallel operation modes are adopted . However , the existing design rules and specifications are no longer applicable to the calculation of multiple parallel operation parameters of multi - circuit cables .

In this paper , we attempt to establish a refined model of the temperature field calculation of the multi - return cable line in parallel with a plurality of parallel cables with the circulation and current distribution of the sheath and sheath , and study the practical situation of the six return line projects , such as 220 kV Pingjiang Line . The main results are as follows :

Firstly , the electric cables are classified according to the indexes such as insulation material , voltage class , structural characteristics , laying conditions , etc . The basic structure of YJLW02 - 127 / 220 kV XLPE cable with a cross - sectional area of 2000mm2 is described . Then , four common laying methods of cable line , i.e . , direct - buried laying , pipe laying , cable trench laying and tunnel laying , are introduced in detail . Finally , a selection evaluation system covering reliability , economical type , monitorable property and current carrying capacity is established .

( 2 ) The current distribution method of the sheath circulation and the in - phase parallel cable is deduced and the current distribution of the two cables in the same phase is calculated , and the current distribution of the two cables in the same phase is calculated and the comparison study is carried out . The basis of the refined model for the calculation of the temperature field of the six return lines , such as the 220kV Pingjiang line , which is the circulation and current distribution of the sheath , is calculated .

( 3 ) according to the specific parameters of the six return lines such as 220 kV Pingjiang line and the laying mode , the section physical model of the temperature field calculation is firstly established ;
Then , according to the principle of heat transfer , the steady - state heat - conduction differential equation in the cable group and its surrounding lay - up area is established , and the calculation and value of the temperature field of the six - return line , such as the initial condition , the loss value of internal heat source and the thermodynamic parameters are calculated and taken according to the contents of 2 . The solution region is automatically divided by triangular meshes and solved by the steady - state heat conduction differential equation , so that the temperature distribution of the cable group and the surrounding laying area is obtained under the rated load current of 100 % and the rated load current of 120 % ;
Finally , the current carrying capacity of each segment cable line is calculated and analyzed by means of double - point chord cutting method .

In this paper , the influence of cable laying condition , such as depth of cable trench , spacing of cable layer and external environmental factors such as air temperature , coefficient of thermal resistance of soil and external environmental factors such as air temperature and soil thermal resistance coefficient are analyzed .

【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM75

【参考文献】