纳米复合填充物对水树的修复及其在多因子老化下的作用机理研究

For the water treeing deterioration in service XLPE cables in a power grid, a silicone liquid injection technology is proved to be an effective method to extend the service life of the water treeing cables. However, the previous research for water treeing rejuvenation mainly focuses on the organic filling in water treeing voids. An inorganic nano rejuvenation method and mechanism is still not involved to the water treeing rejuvenation research. In this research, a new nano rejuvenation liquid (including metal alkoxides components and coupling agents) is used to inject the water treeing samples with a pressurized injection system. As a result, the new rejuvenation liquid can react with water and generate inorganic nano compound fillers in the water treeing voids. Through comparing the electrical behaviors and microstructures of the water treeing voids before and after injection, relationships can be obtained between components of the rejuvenation liquid and microstructures of the fillers in the water treeing voids. Also, in order to obtain the relationship between the microstructures of fillers and behaviors of water treeing and electrical treeing, initiation and propagation of water treeing and electrical treeing are investigated for the injected samples. Moreover, in order to analyze the interaction mechanism of the XLPE and the nano compound fillers in water treeing voids under AC voltage, temperature and impulse voltage, the changes of the dielectric properties and the microstructures of the water treeing after injection are investigated with the increase in aging time. This research is expected to reveal the relationships among components of the inorganic nano rejuvenation liquid, changes of the micro structures in water treeing after injection and changes of the dielectric properties of injected samples.

针对电网中XLPE(交联聚乙烯)电缆的水树老化问题，研究表明,通过一种有机硅修复液从缆芯压力注入水树老化电缆后，可大大延长这些老化电缆寿命。过去的研究主要关注水树的有机物填充修复，对于水树的无机纳米复合填充修复及该填充物的深层作用机理尚未涉及。本项目以水树老化的XLPE薄片和电缆为研究对象，采用新的纳米修复液（包括金属醇盐和偶联剂等成分）对样本进行修复，在水树空洞内通过水解-缩合反应生成无机纳米复合填充物。通过修复后水树空洞内填充物的介电特性和微结构变化特征，摸清修复液对水树空洞内生成填充物的微观结构的影响规律。同时，通过对修复样本的水树、电树的引发和生长实验，摸清该填充物的微观结构特征对水树、电树的引发和生长特性的影响规律。通过温度、交流和冲击电压的老化，摸清填充物微观结构随时间的变化规律及和水树、电树生长特性的关联。项目将揭示无机纳米修复液、修复后样本微观结构和宏观介电行为的关联机制。

在压力作用下硅烷液体注入修复技术能够有效提升水树老化XLPE电缆的绝缘性能并延长其使用寿命，但过去传统的有机填充修复技术在耐局放及长期老化性能尚有不足。本项目提出了一种新的基于有机-无机纳米复合填充（包括金属醇盐和偶联剂等成分）的修复技术对水树老化电缆实现修复，分析了修复液在水树空洞内生成填充物对水树微观结构的影响规律，研究填充物的微观结构特征对水树、电树的引发和生长特性的影响规律。同时通过温度、交流和冲击电压的老化，摸清填充物微观结构随时间的变化规律及与水树、电树生长特性的关联。主要成果包括：提出了一种在水树通道内自生成纳米复合填充物的电缆修复液，通过修复液在水树通道内的水解缩合反应自生成纳米复合填充物（即：无机纳米颗粒+偶联剂+基体），该结构能够填充水树空洞并实现和基体的良好结合，均匀局部畸变电场，阻挡局部放电的侵蚀，从而抑制水树生长及电树的引发。在电、热协同老化过程中，水树空洞内部生成的填充物仍能够在偶联剂的作用下与XLPE基体紧密结合，同时抑制已有水树的生长与电树的引发，其长期修复效果稳定。项目成果不仅发展了水树老化和修复理论，并为解决城市电网大规模的水树老化电缆问题提供了新的解决思路。