绝缘纸多元功能微纳界面的构筑及其抑制油-纸绝缘界面电荷的机制

The interface charge is a key factor affecting the insulation performance of the converter transformer outlet device. The interfacial charge of oil-paper insulation has the particularity which is dominated by the performance of oil-paper interface. The project is aimed to restrain the influence of interfacial charge on oil-paper insulation performance based on improving the property and micro structure of oil-paper interface. Firstly, the construction method for the multi-functional micro/nano interface which has suppression ability for interfacial charge in oil-paper insulation was studied using the radio frequency magnetron sputtering technology. Under the condition of keeping good performance of the oil-paper insulation, the constructed interface should have the function of weakening the structural defects of insulation paper, weakening the conductivity and dielectric constant gradient difference between oil and insulation paper, enhancing the interface charge transfer rate and effectively inhibiting the charge accumulation. Secondly, the ability and stability of the multi-function micro/nano interface for persistent suppression interface charge in oil-paper insulation were characterized. Finally, the interface charge inhibition mechanism of the multi-function micro/nano interface in oil-paper insulation was explored by the analysis of oil-paper interface performance, including the material microstructure, the "double trap model" parameters, the transverse relaxation behavior and molecular simulation. transverse relaxation behavior and molecular interaction. Through the above work, the problem of interface charge affecting the insulation performance of the converter transformer outlet device would be solved. This research would have important theoretical and engineering value.

界面电荷是影响换流变阀侧出线装置油纸绝缘性能的关键因素。油-纸绝缘界面电荷具有受油-纸界面自身性能主导的特殊性。本项目首次聚焦油-纸界面微观结构和功能属性的改善，抑制界面电荷对油纸绝缘性能的影响。首先，以射频磁控溅射技术为技术手段，开展抑制油-纸绝缘界面电荷的绝缘纸多元功能微纳界面构筑方法研究，在保持油-纸绝缘良好性能前提下，实现界面三大功能构筑：弱化绝缘纸结构性缺陷、弱化油-纸间电导率和介电常数梯度差异、构建电荷迁移通道并提升油-纸界面层电荷迁移率。其次，对多元功能微纳界面抑制油-纸绝缘界面电荷的能力及其稳定性进行表征；最后，运用材料显微结构分析、油-纸界面 “改进双陷阱模型”参数分析、界面层横向弛豫行为和分子模拟分析，探索多元功能微纳界面抑制油-纸绝缘界面电荷的机理。通过上述三方面研究，解决界面电荷对换流变出线装置油纸绝缘性能影响这一难题。项目成果具有重要的理论和工程价值。

换流变压器是超/特高压直流工程的关键核心装备，换流变压器阀侧出线装置具有稳定的绝缘性能是保证换流变可靠运行的关键。然而，界面电荷是影响换流变阀侧出线装置油纸绝缘性能的关键因素，且油-纸绝缘界面电荷具有受油-纸界面自身性能主导的特殊性。本项目首次聚焦油-纸界面自身性能的改善实现抑制界面电荷对油纸绝缘性能的影响，取得三方面创新成果，体现如下：.（1）基于量子化学计算获得了三种典型微纳功能层物质（半导体类氧化物ZnO，绝缘类氧化物Al2O3、绝缘类聚合物PTFE）与纤维素相互作用的行为差异，提出了绝缘纸板表面微纳功能层构筑物质的优选组合及排序,为微纳功能层构筑提供了理论指导和方法借鉴；.（2）发明了绝缘纸板表面微纳功能层的射频反应磁控溅射构筑及性能调控方法，成功在绝缘纸板表面构筑了单一Al2O3、PTFE微纳功能层、多元功能Al2O3/PTFE复合微纳功能层，获得了不同类型复合微纳功能层抑制绝缘纸板电荷积聚和提升绝缘强度的规律及效果。与空白油浸绝缘纸板相比，直流15 kV/mm下PTFE/Al2O3复合微纳功能层油浸绝缘纸板内部积聚的电荷总量减少了40%，油隙与油浸纸板组合体系的稳态界面电荷密度减小42%，电荷积聚量减少45%；PTFE/Al2O3复合微纳功能层油浸绝缘纸板内部空间电荷积聚引起的电场畸变率由33.3%降至6.7%，无预压和直流预压击穿电压分别提高了5.3%和15%；PTFE/Al2O3复合微纳功能层油浸绝缘纸板的多次沿面闪络电压均高于空白油浸绝缘纸板，且放电损伤程度较弱；构筑在绝缘纸板表面的PTFE/Al2O3复合微纳功能层能保持长期稳定性。.（3）揭示了多元功能PTFE/Al2O3复合微纳功能界面抑制油-纸绝缘界面电荷的作用机制，一是弱化绝缘纸表面结构性物理缺陷，二是提升界面势垒和电荷捕捉能力，三是增大陷阱密度，抑制电荷注入和降低载流子迁移率，提升绝缘强度。.本项目通过上述三方面创新成果，助力解决界面电荷对换流变出线装置绝缘性能影响这一难题，项目成果将具有重要的理论和工程价值。