多应力下电缆附件界面的绝缘老化及修复填充物的作用机理研究

Faults usually occur in urban power grids for cable accessories aging, but present solutions are simple and passive for the faults. The previous rejuvenation achievements mainly focus on water-tree rejuvenation in cable insulation. These researches are still not involved in filling in micro defects and their further mechanisms of action in insulation interfaces for cable accessories. Interface unit models and actual cable accessories are used for the research objects in the proposal. Electrical performances of insulation interface, including breakdown voltage, trap level, polarization-relaxation characteristics, electrical treeing initiation and partial discharge characteristics, are investigated under single and combined stresses with thermal, electrical and environmental stresses. The micro structure of interface and migration characteristics of silicone grease is also investigated in the insulation interface under the single and combined stresses. The relationships among them are studied to understand early degradation mechanism in the interface. A new silane coupling agent and phenolic antioxidants are used to produce the hydrolysis-condensation reaction and chemical bond in the interface. Based on these researches, it is achieved that the relationship among rejuvenation fluid components, micro-structure of interface and electrical performance. The effects of rejuvenation conditions are also investigated on micro structures and electrical performances for rejuvenated samples. The long-term mechanism of action of rejuvenation fillers is obtained in the interface cavities under effects of multiple stresses. This research is expected to reveal aging and rejuvenation mechanisms of cable accessories under multiple stresses.

针对城市电网中出现的大规模电缆附件老化所导致的频繁故障，现有解决手段单一而被动。过去的绝缘修复主要关注对电缆本体的水树进行绝缘修复，对于电缆附件的绝缘界面处存在的微观缺陷进行修复填充以及填充物的深层作用机理尚未涉及。本项目拟以界面单元模型和实际电缆附件为研究对象，研究它们在温度、电场及环境湿度等单一或多应力作用下其绝缘界面的介电性能（击穿电压、陷阱能级、极化-松弛特性、电树引发和局放特征等）、微观结构（物理和化学结构）、填充小分子迁移特性及它们间的关联规律，阐明其早期老化机理。采用新的硅烷偶联剂和酚类抗氧剂对绝缘界面的空腔进行水解-缩合并与基体形成化学键结合，以建立修复液成分、界面微观结构变化、修复后的介电性能三者之间的关联机制，探究修复条件对修复后样本微观结构和介电性能的影响规律。在复合应力作用下，研究修复填充物对界面空腔的长期作用机理。项目将揭示电缆附件在多应力作用下的老化和修复机理。