等温松弛电流法在高压交联聚乙烯绝缘交流电缆状态评估中的应用  

Application of Isothermal Relaxation Current Technique in Condition Assessment for XLPE HVAC Cables

作　　者：朱永华[1] 高小庆[2] 杨娟娟[1] 贾欣[1] 

机构地区：[1]上海电缆研究所,上海200093 [2]国网上海市电力公司检修公司,上海200072

出　　处：《高电压技术》2016年第2期513-521,共9页High Voltage Engineering

摘　　要：为探讨等温松弛电流法在高压交流(HVAC)电缆状态评估中应用的可行性,采用等温松弛电流法(IRC)对未老化和运行13 a的国产110 k V高压交联聚乙烯(XLPE)交流电缆进行了老化评估,并研究了直流电场下电缆绝缘切片的空间电荷分布,分析了绝缘内部的陷阱分布、松弛机理和绝缘状态的关联性。结果表明,未老化高压电缆的老化因子>1.89,绝缘切片样品表面区域存在明显的异极性空间电荷积累,残留在高压电缆内部的交联副产物以深能级陷阱形式存在,并与等温松弛电流中的第3类松弛相对应。运行13 a的高压电缆的老化因子明显高于未老化电缆的老化因子,且其绝缘切片表面区域的异极性空间电荷积累量和切片内部的最大电场畸变率增大,与等温松弛电流法提取的老化因子变化规律相同。因此老化因子可作为高压交流电缆绝缘老化状态的评估参数。Two types of 110 kV high voltage alternating current （HVAC） cable samples, i.e. unaged and 13-year-fieldaged cable samples, were selected to investigate the feasibility of isothermal relaxation current （IRC） method on insulation condition evaluation for XLEP insulated HVAC cable. At the same time, the space charge of sheet samples sliced from cable insulation was also carried out to analyze trap distribution and relaxation mechanism associated with the insu- lation aging condition. It is found that the aging factor of unaged sample acquired by IRC is higher than 1.89, and a lot of heterocharge accumulates near the surface of the sliced samples. Meanwhile, the crosslinking byproducts residing in the insulation act as deep traps. These deep traps are associated with the third type of relaxation deduced from the isothermal relaxation current, which leads to a high aging factor. Aging factor of aged cable is significantly higher than that of unaged cable. Furthermore, the heterocharge accumulation and the maximum distortion electric field evaluated by space Charge distribution distinctly increase in the aged cable, which are the same variation trends as the aging factor acquired by the isothermal relaxation current. Therefore,the IRC method can be applied to condition assessment for XLPE insu lated HVAC cable.

关 键 词：高压电缆 交联聚乙烯 等温松弛电流法 空间电荷 老化因子 最大电场畸变率 

分 类 号：TM75[电气工程—电力系统及自动化]