交流XLPE电缆改为直流运行时空间电荷积累特性仿真  

Simulation on the Characteristics of Space Charge Accumulation When Converting the AC XLPE Cable to DC Operation

作　　者：刘士利[1] 李丛健 沈方 王春生 蔡国伟[1] 宋卓然 

机构地区：[1]东北电力大学电气工程学院,吉林132012 [2]国网辽宁省电力有限公司经济技术研究院,沈阳110015

出　　处：《高电压技术》2017年第11期3576-3582,共7页High Voltage Engineering

基　　金：国家电网公司科技项目(5222JJ14002)~~

摘　　要：将交流电缆线路改为直流运行可以充分利用原有输电线路走廊,最大限度地发挥原有输电线路的输送能力。为研究交流交链聚乙烯(XLPE)电缆在直流电压下的电场分布和空间电荷积累特性,应用COMSOL多物理场仿真软件,模拟了温差为25℃及45℃时电缆绝缘层中的温度场,并基于绝缘试片电导率数学模型,研究了66 kV电压等级交流XLPE电缆在直流电压下的电场分布和空间电荷积累特性。计算结果表明:电缆绝缘层的电场分布和空间电荷积累特性会明显受到温差的影响,当温差为45℃、加压时间为8 h时,低温侧空间电荷密度达0.15C/m^3,此时电场分布发生翻转现象,绝缘层外侧电场强度最大值为6.71 MV/m,该数值低于66 kV电压等级交流电缆绝缘层的电场强度设计值。仿真结果为66 kV电压等级电缆线路的交改直运行奠定了基础。Converting the existing cable lines from AC to DC operation, can make full use of the existing transmission corridor and maximize the transmission capacity of the original AC transmission lines. In order to investigate the charac- teristics of space charge accumulation and electric field distribution in the AC XLPE cable under DC voltage, the COMSOL Multi-physics software was used to simulate the thermodynamic temperature distribution at temperature dif- ference of 45 ℃ and 25 ℃. The electric field distribution and the characteristics of space charge accumulation, based on the mathematical model of conductivity under DC voltage in the 66 kV AC XLPE power cable, were also simulated. The simulation results indicate that the temperature difference in the cable has a remarkable influence on the accumula- tion of space charge and the distribution of electric field. The reversal phenomenon will occur in the cable insulation and the maximum electric field will appear outside the insulation when stressing time is 8 hours and space charge density is 0.15 C/m3 at temperature difference of 45 ℃. The maximum electric field will be 6.71 MV/m, which is relatively safe for the actual operation of the AC cable. The simulation results have laid a foundation for converting the existing 66 kV AC cable lines from AC to DC operation.

关 键 词：增容改造 空间电荷 电场强度 温差 COMSOL 交流XLPE 

分 类 号：TM75[电气工程—电力系统及自动化]