电热联合老化对高压XLPE电缆绝缘介电频谱特性的影响  

Effect of Electrothermal Combined Aging on Dielectric Spectrum Properties on High Voltage AC XLPE Cable Insulation

作　　者：陈健涛 赵一枫 范星辉 刘刚[1] CHEN Jiantao;ZHAO Yifeng;FAN Xinghui;LIU Gang(Guangdong Key Laboratory of Clean Energy Technology,School of Electric Power,South China University of Technology,Guangzhou,Guangdong 510641,China)

机构地区：[1]广东省绿色能源技术重点实验室(华南理工大学电力学院),广东广州510641

出　　处：《广东电力》2022年第9期117-126,共10页Guangdong Electric Power

基　　金：国家自然科学基金项目(51977083)。

摘　　要：为了研究实际运行过程中不同负荷条件下电热因素对高压XLPE电缆绝缘的介电频谱特性的影响,对2回30 m长的110 kVXLPE电缆进行为期180 d的电热联合加速老化试验。试验电压设定为95 kV,试验温度设定为90℃,其中一回电缆采用恒温老化方式,另外一回采用周期性热循环老化方式。通过介电频谱实验获取常温下电缆绝缘的相对介电常数和介质损耗正切角随频率变化的曲线,并进一步分析试验前后不同老化方式对电缆绝缘宏观电场分布的影响。结果表明:在电热恒温老化方式试验后,在电缆绝缘内、外层,极性低分子含量下降和主结晶晶态结构改善使得极化过程减弱,且介质损耗降低,在绝缘中层大量极性低分子的积聚和次级结晶的增多加剧了极化过程,增大了介质损耗,最终使得绝缘的整体电场分布发生翻转;在电热循环老化方式试验后,由于晶体结构改善,绝缘内层漏导损耗下降且弛豫极化向低频段处前移,在绝缘中、外层,极性低分子的减少使得介质损耗降低,绝缘的整体电场分布更加均匀。In order to study the influence of electrothermal factors on the dielectric spectrum characteristics of high voltage AC XLPE cable insulation during its actual operation under different loading conditions,two circuits of 110 kV XLPE cable with a length of 30 m were subjected to electrothermal combined accelerated aging test for 180 days.The test voltage was set at 95 kV and the test temperature was set at 90℃.One circuit of the cable adopted constant temperature aging mode and the other adopted periodic thermal cycle aging mode.The relative dielectric constant and dielectric loss tangent of cable insulation at room temperature were obtained by dielectric spectrum experiment,and the influence of different aging modes on the macroscopic electric field distribution of cable insulation before and after aging test was further analyzed.The results show that after the electrothermal constant temperature aging test,the polarization process of the inner and outer layers of cable insulation is weakened and the dielectric loss is reduced due to the decrease of the content of low polar molecules and the improvement of the main crystalline crystal structure.Due to the accumulation of a large number of low polar molecules and the secondary crystallization in the middle layer of insulation,the polarization process becomes more intensive,increasing the dielectric loss.Eventually,the overall electric field distribution of the insulation is reversed.After the electrothermal cycle aging test,the leakage loss of the inner insulating layer decreases and the relaxation polarization moves forward to the low frequency band due to the improvement of the crystal structure.The reduction of low polarity molecules in the middle and outer layers of insulation causes the dielectric loss reduce and the overall electric field distribution of insulation becomes more uniform.

关 键 词：XLPE电缆 介电频谱 电场分布 傅里叶红外光谱 差示扫描量热 

分 类 号：TM247[一般工业技术—材料科学与工程]