新型环保混合气体的冷态与热态电击穿协同效应研究

The strong greenhouse effect and high liquefaction temperature are the two serious environmental problems in the applications of SF6 gas as an insulation and arc-quenching medium in electric power apparatus. Recently, C5F10O and C6F12O, whose dielectric strengths are superior to SF6 gas while liquefaction temperatures are relatively high, attract great attentions. However, the knowledge of the cold and hot dielectric breakdown properties of their mixtures and the matching principle for buffer gas are still finite. This project aims to investigate the synergistic effect of the dielectric breakdown property in the mixtures of two new enviroment-friendly gases at room and elevated temperatures, including C5F10O and C6F12O. The precise simulation and the advanced diagnostics technique are used to analyze the transient micro-parameters and processes of streamer discharges. Aimed at the determination of the gas mixture species and concentration, more attentions are paid on the exploration of the influences of the rise rate of voltage, shape of the electric field, pressure, etc. on the synergistic effect of the dielectric breakdown property in cold gas mixtures, and on the microscopic physical mechanisms of the synergistic effect and matching principle. Then the dielectric breakdown properties and their synergistic effect in hot gas mixtures will be studied, and the influences of mixed ratio, pressure, electron and heavy particle temperatures and excitation temperature will also be analyzed. The prospective achievements could promote the development of the gas discharge theory, and provide supports and references for the research and development of the next generation new type enviroment-friendly electric power apparatus.

SF6作为绝缘与灭弧介质在电力设备中使用时面临温室效应和液化温度高这两个重要的环境问题，近期C5F10O、C6F12O这种绝缘强度优于SF6而液化温度较高的气体受到关注，但对其混合气体的冷态与热态电击穿特性及缓冲气体的匹配原则等问题认识有限。本项目重点针对C5F10O和C6F12O两种新型环保气体的混合气体，利用精确的数值模拟和精密的等离子体诊断技术来定量分析流注放电的微观、瞬态参数和物理过程，瞄准如何确定新型环保混合气体种类与配比这一核心问题，重点探索电压上升率、电场均匀性、压力等因素对混合气体冷态电击穿协同效应的影响规律，以及电击穿协同效应的微观物理机制与匹配原则；进而研究组分比例、压力、电子与重粒子温度、激发温度等因素对新型环保混合气体的热态电击穿特性与协同效应的影响规律。本项目研究有助于推动气体放电理论的发展，为我国掌握下一代新型环保电力设备的核心技术提供重要的理论依据和技术参考。

六氟化硫气体（SF6）具有优良的绝缘与灭弧性能，在中高压电力设备中得到了广泛应用，然而，SF6是目前已知最强的温室气体之一，已被要求限制甚至停止使用。近几十年来，国内外针对SF6的替代技术开展了大量持续的研究工作，但至今仍未找到一种综合性能与SF6气体相当的环保型气体。氟化酮C5F10O、氟化腈C4F7N等气体具有极强的绝缘性能和较好的环保性能，近期受到重点关注，且在国外已有应用案例，但国内当前研究相对滞后，尤其对其混合气体的冷态与热态电击穿特性及缓冲气体的匹配原则等问题认识有限。本项目重点针对上述新型环保气体的混合气体，通过数值模拟和诊断技术，系统低研究了新型环保气体的冷态与热态电击穿特性，以及其与不同缓冲气体的协同效应，在此基础上研究了气体的匹配原则及物理机制。通过本项目研究内容的开展，揭示了新型环保混合气体电击穿协同效应的物理机制，提出了饱和蒸气压与临界击穿场强约束下的混合气体组配原则，确定了环保混合气体适用于不同海拔、环境温度下电力设备的配比和压力优选方案，突破了中压电力设备在高海拔地区“零表压”运行技术，研制出多品类新型环保气体绝缘电力设备，通过型式试验。