基于微观界面荷电表征的纳米电介质老化机制及抑制方法研究

With the rapid development of voltage level and transmission capacity, the problem of insulation aging of high-voltage power equipment has become increasingly prominent. Nano-dielectrics provide new idea to solve the insulation reliability problems in complex environments, due to its unique interface effects and functionalities. The micro-interface has a crucial impact on the macroscopic properties of nano-dielectrics. However, the study on the micro-interface charge characteristics and the mechanisms about its influence on aging properties are still lack of research. In order to explore the micro-interface charge evolution, and then reveal its effects on nano-dielectrics aging, our research intends to use the silicone rubber materials used for DC cable accessories as the research object. Firstly, we propose a new method to calculate the dynamic charges and trap distribution characteristics on micro-interface quantitatively, and then the micro-interface charge transportation mechanisms are clarified. Secondly, we establish the internal relationship between the micro-interface charge evolution and the electrical properties of aging insulation, revealing the mechanisms of micro-interface on the insulation aging. Lastly, based on the researches above, a nano-interface controlling method for suppressing electro-thermal aging of silicone rubber would be proposed. The research is expected to provide new ideas, new theories and new methods for the micro-interface characterization and orientation control for nanocomposites, and further provide a theoretical basis for the development and state evaluation of the main insulation materials of high-voltage DC cable accessories.

随着我国电压等级和输送容量的高速发展，高压电力设备的绝缘老化问题日益凸显。纳米电介质因其独特的界面效应及功能性，为解决复杂环境下设备绝缘可靠性问题带来了希望。微观界面对纳米电介质宏观性能起到决定性影响，然而目前尚缺乏微观界面荷电特性及其对绝缘老化性能的影响研究。为了探寻微观界面荷电演变规律，进而揭示微观界面对纳米电介质老化的作用机制。本项目拟以直流电缆附件用主绝缘材料——硅橡胶为研究对象，首先，建立纳米界面动态荷电及陷阱分布特性的表征与定量计算方法，阐明微观界面电荷输运机制；其次，建立电热老化下纳米硅橡胶微观界面荷电演变与绝缘老化性能的内在关联关系，从而理清纳米界面对绝缘老化的作用机制；最后，基于上述研究，提出抑制硅橡胶电热老化的纳米界面调控方法。项目的开展有望为纳米复合材料微观界面荷电表征和定向调控提供新思路、新理论和新方法，以期为高压直流电缆附件主绝缘材料的研发和状态评估提供理论基础。

随着清洁能源的大规模利用和全球能源互联战略的持续推进，高压直流电缆发展迅猛。然而，高电压等级直流电缆设计、运行和维护经验不足，电缆绝缘材料设计缺乏依据和标准等问题，高压直流电缆运行的可靠性仍无法保障。电介质因其独特的界面效应及功能性，为解决复杂环境下设备绝缘可靠性问题带来了希望。目前，大多数的研究主要停留在纳米电介质短期性能提升方面，而其长期老化性能及影响机制仍缺乏系统的研究。本项目围绕纳米电介质荷电演变规律及其对绝缘老化性能的影响机制这一关键科学问题。首先，建立了静电力显微镜探针与界面微区的电容模型，研究了探针形状、聚合物基体参数、界面效应等对静电力梯度及电气性能的影响过程。其次，研究了热-力联合老化作用下硅橡胶材料微观结构及电气性能变化规律，建立基于“壳层结构模型”的硅橡胶物理弱区模型；建立了双极性载流子输运模型，阐明了老化状态下绝缘材料电荷输运对劣化过程的影响。最后，获得了良好分散性、纳米界面可控的纳米复合硅橡胶材料，发现在未老化时，适量纳米粒子的掺杂可以改善硅橡胶相关的特性，但在强热力联合老化作用下，会进一步加剧纳米复合硅橡胶性能的劣化。纳米复合硅橡胶在短期性能方面要优于纯硅橡胶，但在多场作用下的长期性能还需要进一步改进。相关研究为复合材料性能调控提供新方法，也为高压直流电缆附件绝缘材料研发和状态评估奠定理论基础。