持续局部放电下含碳类SF6替代介质的化学沉积物形成机理及抑制优化策略的研究

Due to excellent electrical performance and environmental friendliness, carbon containing SF6 alternatives as the important dielectrics have gained wide attentions for decade years. However, under the continuous partial discharge, carbon containing SF6 alternatives will decompose and generate by-products, including gas and solid by-products. Wherein, the solid by-products will destroy the long-term insulation properties. Therefore, in this project, taken c-C4F8 and C6-PFK as the main study objects, the formation mechanisms of their solid by-products will be analyzed by carrying out a series of experiments of continuous partial discharge. Then, candidate buffer gases will be searched according to the chemical properties of the carbon containing SF6 alternatives and the solid by-products. Consequently, the optimized inhibition indexes of the solid by-products will be presented, to stand for both the characteristics of dielectric performance and the solid by-products inhibition. Finally, a optimized inhibition model will be established that considers the long-term insulation performance. The purpose of this project is to provide a widely used optimization strategy for solid by-products inhibition. Herein, the study on transformation process from the carbon containing SF6 alternatives to the solid by-products is the basis, and the search on buffer gases is the key, further establishing the relationship between the solid by-products and buffer gases. As a result, the related rules and models can provide the theoretical basis and criteria for the solid by-products inhibition, to realize the real application of the carbon containing SF6 alternatives in gas insulated electrical equipment.

作为重要的SF6绝缘替代介质，含碳类化合物因良好的电气性能和环境友好性受到了关注。然而，实验显示，持续局部放电下含碳类化合物将电离分解进而生成化学沉积物，由此破坏气体的绝缘性能。本项目结合量子化学计算和实验研究，以C6F12O和C5F12O为主要研究对象，探讨持续局部放电下化学沉积物的生成机制和变化规律；从认识化学沉积物的产生根源着手，搜寻可抑制化学沉积物且能保持良好绝缘性能的缓冲气体，形成综合表征化学沉积物与绝缘性能的优化指标，建立考虑绝缘性能的多边界化学沉积物抑制模型，为含碳类化合物的实际应用提供具有普遍意义的沉积物抑制优化策略。其中，持续局部放电下化学沉积物的演化过程是基础；搜寻抑制类缓冲气体并建立与化学沉积物的对应关系是关键；绝缘性能的综合评价是优化抑制化学沉积物的必要条件；综合化学沉积物抑制和绝缘性能的优化策略是推动含碳类化合物实用化的根本，也是本项目的最终目的。

本项目以全氟异丁腈C4F7N、全氟五碳酮C5F10O和全氟六碳酮C6F12O为研究对象，开展了电晕放电、火花放电、沿面放电等系列实验，结合量子化学计算，分析了环保绝缘介质的分解特性及固体沉积物的生成原因。首先，建立了基于气相色谱-质谱联用技术的C4F7N, C5F10O和C6F12O及其分解物检测方法，对分解气体进行了测定；利用扫描电镜、傅里叶红外光谱、XRD等技术对固体产物进行了检测和分析。从分解特性角度综合比较了环保绝缘介质与N2、CO2或空气组成的二元混合气体的气体分解物和固体分解物。其次，结合实验与理论分析，揭示了C4F7N混合气体固体沉积物的生成原因；提出的C3HF7分解机理及C3F6生成机理的理论计算为实验研究提供了新思路。在此基础上，建议设备运行过程中应严格监测和控制内部的含水量，以防产生高浓度的HF气体，降低其使用寿命或危害设备的稳定运行。最后，综合电气设备实际应用环境以及替代气体的分解特性、液化温度、绝缘性能、传热特性等，提出了C4F7N, C5F10O等气体的缓冲气体及混合比例建议。.本项目获得了C4F7N, C5F10O和C6F12O混合气体的分解特性，建立了气相色谱-质谱检测方法，掌握了不同放电条件下的分解规律，为环保绝缘介质的配置方案提出了优化建议。环保气体分解特性及缺陷识别的相关研究为1100kV 环保 GIL样机研制和10kV开关柜样机研制提供了关键基础数据。