纳米SiO_2/芳纶绝缘纸复合材料的空间电荷特性和介电性能

Space Charge Characteristics and Dielectric Properties of Nano-SiO_2/Aramid Paper Composite

为提高油纸绝缘系统的绝缘寿命,提出将纳米SiO_2粒子改性的芳纶绝缘纸应用于直流输变电设备的方法。在加压和去压短路条件下,测试了不同纳米SiO_2含量的芳纶绝缘纸试样的空间电荷特性、热刺激去极化电流、直流击穿强度和体积电阻率。结果表明:添加纳米SiO_2使芳纶绝缘纸的线均电荷密度明显低于纯芳纶纸试样;随纳米SiO_2含量的增加,试样平均电荷密度衰减速率呈现先减小后增大的变化趋势;SiO_2的添加增加了芳纶纸内部深陷阱和浅陷阱的密度;纳米SiO_2含量为1wt%时直流击穿强度最大;芳纶纸的体积电阻率随纳米SiO_2含量增加呈单调递增趋势。机理分析表明纳米SiO_2粒子浓度过高时,其分散性变差导致其对芳纶纸性能的改善作用变弱。

In order to apply aramid paper in the DC power transmission equipment to increase the life expectancy, the method of nano-SiO_2 particle modified aramid insulation paper is proposed to improve the space charge properties and DC dielectric properties. The aramid insulation paper samples with different nano-SiO_2 contents wad presented. The space charge characteristics, the thermally stimulated depolarization current（TSDC）, DC breakdown voltage and volume resistivity of aramid papers with different SiO_2 contents were measured respectively under increasing voltage and short circuit conditions. The results show that nano-SiO_2 could efficiently prevent the space charge injection. The medium charge density of nano-modified aramid paper samples is smaller than that of the pure aramid paper sample during the voltage-on process. With the increasing percentage of nano-SiO_2, the decay rate decreases at the first and then increases. The result of TSDC indicates that nano-SiO_2 increases the density of deep trap and shallow trap simultaneously. The DC breakdown strength of the sample with 1%wt nano-SiO_2 is the maximum. The volume resistivity of aramid papers increases with the increasing of nano-SiO_2 content. When the concentration of nano-particle is too high, the improvement of aramid paper performance is weakened as a result of poor dispersion.