以SF6混合气体为介质的气体绝缘输电线路(GIL)绝缘击穿特性计算

论文总字数：34341字

摘 要

气体绝缘输电线路（Gas Insulated Transmission Line, GIL）具有输电容量大、输送损耗小、体积小、占地面积小等优点，在大容量、远距离电力传输中具有显著优势。目前投运的GIL线路多使用纯SF₆气体作为绝缘介质，然而SF₆气体存在诸如温室效应指数高、价格昂贵等缺点，制约了GIL技术的大规模运用，因此寻找环保、廉价的SF₆替代气体就显得尤为重要。本文通过理论计算研究了各类SF₆混合气体的绝缘击穿特性，采用数值求解Boltzmann方程的方法，得到了各类SF₆混合气体的电子能量分布函数（Electron Energy Distribution Function, EEDF）和有效电离系数，进而求得混合气体的约化临界击穿场强。

本文比较了包括SF₆-CO₂、SF₆-N₂、SF₆-O₂、SF₆-CF₄、SF₆-空气、SF₆-Ar在内的二元混合气体的绝缘击穿特性。计算结果显示，在理想状态下SF₆-N₂混合气体拥有最好的绝缘性能，当混合气体比例为1:1时，临界击穿场强约为317.6 Td。同时，本文还分析了各类混合气体在不同环境下的最佳应用方案。此外，本文针对三元混合气体的绝缘击穿特性进行了深入研究，计算结果表明，三元混合气体SF₆-CO₂-N₂拥有较强的耐电性能，SF₆-CO₂-CF₄与SF₆-N₂-CF₄混合气体能够在多种复杂情况下良好工作，这三种混合气体均为理想的GIL绝缘替代气体。

关键词：SF₆混合气体，绝缘击穿特性，GIL，电子能量分布函数，有效电离系数

Abstract

The Gas Insulated Transmission Line (GIL) has the advantages of large transmission capacity, small transmission loss, small volume, and small footprint, and has significant advantages in large-capacity and long-distance power transmission. Currently, GIL mostly uses pure SF₆ gas as the insulating medium. However, SF₆ gas has many shortcomings, such as the high global warming potential and the high prices, which restricts the application of GIL technology. It is therefore necessary to study the alternative gases of SF₆ in GIL. In this paper, the dielectric breakdown characteristics of SF₆ mixtures were studied by theoretical calculation. The Boltzmann equation was used to obtain the electron energy distribution function (EEDF) and the effective ionization coefficients of the mixture, and then the reduced critical dielectric field strength of the mixture was obtained.

In this paper, the dielectric breakdown characteristics of binary mixtures including SF₆-CO₂, SF₆-N₂, SF₆-O₂, SF₆-CF₄, SF₆-air, and SF₆-Ar were calculated and compared under ideal conditions. The results show that SF₆-N₂ mixture presents the best dielectric performance. When the ratio of mixture is 1:1, the critical electrical field strength is approximately 317.6 Td. In addition, the breakdown characteristics of the ternary mixture were also studied in this paper. The results show that the ternary mixture SF₆-CO₂-N₂ has excellent insulating ability, and SF₆-CO₂-CF₄ and SF₆-N₂-CF₄ mixtures can work well in a variety of complex situations, and these three mixtures are ideal alternatives to gas-insulating medium in the GIL.

KEY WORDS: SF₆ mixture, dielectric breakdown properties, GIL, electron energy distribution function, effective ionization coefficient

目 录

摘要 I

Abstract II

第一章 绪论 1

1.1. 选题背景及其意义 1

1.2. GIL技术的现状及发展 1

1.3. 绝缘气体研究现状 3

1.4. 本文主要研究内容 4

第二章 气体绝缘击穿特性的研究方法 5

2.1. 气体绝缘击穿的实验研究 5

2.2. 气体绝缘击穿的理论研究 5

2.2.1. 电离过程 6

2.2.2. 吸附过程 6

2.3. Boltzmann方程的求解 6

2.4. 电子输运系数与概率系数 9

2.5. 碰撞截面 11

第三章 二元混合气体绝缘击穿特性分析 13

3.1. 电子能量分布函数（Electron Energy Distribution Function, EEDF） 13

3.2. 有效电离系数与临界击穿场强 18

3.3. 混合气体绝缘击穿特性比较 24

第四章 三元混合气体绝缘击穿特性讨论 26

4.1. SF₆-CO₂-N₂混合气体 26

4.2. SF₆-CO₂-O₂混合气体 28

4.3. SF₆-CO₂-CF₄混合气体 29

4.4. SF₆-N₂-CF₄混合气体 31

第五章 结论与展望 34

5.1. 结论 34

5.2. 不足与展望 34

致谢 36

参考文献 37

第一章 绪论

选题背景及其意义

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