环氧基纳米复合绝缘材料沿面闪络气-固耦合作用机理和性能提高的研究

Surface flashover of insulting materials is a key fundamental scientific problem in electrical insulation of advanced power transmission and transformation equipments. Investigations on the surface flashover are significantly important for the development of advanced power transmission and transformation equipments and insulating materials. However, the existing models and mechanisms have some shortcomings to interpret the surface flashover phenomena completely and reasonably. The present project will focus on the surface flashover characteristics and mechanisms of epoxy nanocomposites. We will investigate the influences of charge transport properties in the deep surface layer, secondary electron emission properties in shallow surface layer, charge ionization/multiplication in gaseous layer on the surface flashover properties by adopting bulk breakdown percolation model, bipolar charge transport model and continuous time random walk model. In addition, we will explore the coupling mechanisms of charge transport properties in the deep surface layer, charge transport/multiplication properties in shallow surface layer and charge ionization/multiplication in gaseous layer. Then, a novel surface flashover model will be established by considering the coupling mechanisms of charge transport/multiplication properties in the deep surface layer, shallow surface layer and gaseous layer. Furthermore, a theoretical method will be proposed to improve the surface flashover characteristics of epoxy nanocomposites. The project will provide theoretical and experimental basis for the development of advanced power transmission and transformation equipments and insulating materials.

绝缘沿面闪络是先进输变电装备中电气绝缘的关键基础科学问题，该科学问题的研究对于先进输变电装备和绝缘材料的发展具有重要意义。然而，现有模型和机理仍不能全面合理解释沿面闪络现象。本项目围绕绝缘介质沿面闪络特性和机理，以环氧基纳米复合绝缘材料为研究对象，考虑气相表层、气固界面、介质表层中的电荷输运/倍增及其耦合作用，采用介质体击穿逾渗模型、双极性电荷输运和连续时间行走模型，研究介质表层电荷输运，表面二次电子发射特性，气相表层的电离及倍增特性等对沿面闪络的影响规律。进而揭示介质表层电荷输运、表面电荷输运/倍增、气相表层电荷输运/倍增的耦合作用，建立介质表层-表面-气相表层中电荷输运/倍增过程相互耦合的沿面闪络模型。提出提高环氧基纳米复合绝缘材料沿面闪络性能的理论方法。为研制先进输变电装备和纳米复合绝缘材料提供理论基础和实验依据。

气-固界面的沿面闪络一直是高压电力设备、航天器电源系统和脉冲功率装置中的关键科学问题。研究固体绝缘沿面闪络的性能提升，揭示气-固耦合的沿面闪络机理对发展高性能绝缘材料，提高设备运行可靠性和稳定性具有重要的科学和工程意义。本项目围绕环氧基纳米复合绝缘材料气-固耦合的沿面闪络机理和性能提升展开研究；在材料微观陷阱模型和调控、电荷输运过程与沿面闪络性能提升以及气-固耦合的沿面闪络模型等进行了系统深入的研究，取得的主要结果和意义如下：.建立了环氧基纳米复合绝缘材料界面区结构和陷阱分布模型，揭示了纳米调控微观陷阱参数的物理机制；提出了通过改变纳米粒子种类、含量和表面化学修饰的环氧基纳米复合绝缘材料微观陷阱参数的调控方法，实现了其微观陷阱参数的调控；.采用有限差分加权本征非振荡方法（WENO）和三阶龙格-库塔时间离散法，编写了数值计算程序，提高了体和表层电荷输运计算的准确性；.建立了考虑体和表层电荷输运及气体碰撞电离的沿面闪络模型，发现了沿面闪络电压与介质表层陷阱能级呈“U形”关系，实现了环氧基纳米绝缘材料沿面闪络性能提升25%；.从介质表面气体吸附的独特角度，建立了吸附气体浓度分布特性及其对介质表面的静电作用机制，揭示了沿面闪络与介质表面气体吸附的关联； .构建了考虑气体吸附和表层/表面电荷输运的真空和气氛下沿面闪络气-固耦合模型，揭示了广域下的沿面闪络气-固耦合作用机理，为环氧基纳米复合绝缘材料沿面闪络的理论发展和性能提升提供理论基础。.项目取得的主要成果一方面拓展了传统的固体绝缘沿面闪络模型，为沿面闪络科学问题的深入认识和研究奠定了基础；另一方面，提出了通过调控体参数实现表层/表面参数的变化，进而提升固体绝缘介质沿面闪络性能的方法，为工程应用提供了良好的技术基础。