铜蒸气对高压SF6电弧弧后绝缘击穿特性的影响研究

论文总字数：29509字

摘 要

SF₆是一种无色、无味、无毒的工业气体，被广泛用作高压断路器的绝缘和灭弧介质。在高压断路器开断短路电流的过程中，触头间产生SF₆电弧。SF₆电弧的介质恢复特性对高压断路器能否成功开断短路电流至关重要。同时，高温电弧烧蚀断路器的铜质触头还会产生大量铜蒸气，然而前人工作少有考虑铜蒸气对高压SF₆电弧介质恢复特性的影响。事实上，触头电极表面被高温电弧加热而产生的铜蒸气将显著改变SF₆电弧等离子体的物性参数，进而也就可能影响电弧的介质恢复过程。

为了揭示触头烧蚀铜蒸气对高压SF₆电弧弧后介质击穿特性的影响，本文通过数值求解玻尔兹曼（Boltzmann）方程的方法，理论计算了不同铜蒸气浓度（1%Cu、10%Cu、30%Cu以及50%Cu）下，高压SF₆-Cu气体电弧在300-3500 K温度范围内的电子能量分布函数（EEDF）、约化电离系数/N、约化电子吸附系数η/N以及约化有效电离系数(-η)/N，进而得到SF₆-Cu电弧的约化临界击穿场强(E/N)_cr，并以此为基础分析了铜蒸气对SF₆电弧弧后介质恢复特性的影响规律。

本文计算结果显示：铜蒸气的存在能够显著提高SF₆电弧弧后阶段的高能电子的浓度，并且随着铜含量的增加，临界击穿场强(E/N)_cr在3000K以下的温度区间出现了明显降低，但是在3000K以上的温度区间有一定的提高。此外，本文还发现只要铜蒸气比例和气体压强适当，就可以显著改善SF₆的弧后绝缘击穿特性。

关键词：SF₆气体，铜蒸气，绝缘击穿特性，电子能量分布函数，临界击穿场强

Abstract

SF₆ is a colorless, odorless, and non-toxic industrial gas which is widely used as insulation and arc extinguishing media for high voltage circuit breakers. In the process ofbreaking the short-circuit current of the high-voltage circuit breaker, an SF₆ arc is generated between the contacts. The dielectric recovery characteristics of the SF₆ arc are critical to the ability of the high voltage circuit breaker to successfully break the short circuit current. At the same time, the high temperature arc ablating the copper contacts of high-voltage circuit breaker also generates a large amount of copper vapor. However, the previous work has little effect on the recovery characteristics of the high pressure SF₆ arc medium. In fact, the copper vapor generated by the high temperature arc heating of the contact electrode surface will significantly change the physical properties of the SF₆ arc plasma, which in turn may affect the dielectric recovery process of the arc.

In order to reveal the influence of contact ablation copper vapor on the dielectric breakdown characteristics of high-pressure SF₆ arc after arc, this paper theoretically calculated the different copper vapor concentrations (1%Cu,10%Cu,30%Cuand 50%Cu) by numerically solving the Boltzmann equation. Electron energy distribution function (EEDF), reduced ionization coefficient/N, reduced electron adsorption coefficient η/N under high temperature SF₆-Cu gas arc in the temperature range of 300-3500 K and the reduction of the effective ionization coefficient (-η)/N, and then the reduced critical breakdown field strength (E/N)_cr of the SF₆-Cu arc, and based on this analysis of the copper vapor after the SF6 arc The influence law of the medium recovery characteristics.

The calculation results show that the presence of copper vapor can significantly increase the concentration of high-energy electrons in the post-arc arc phase, and with the increase of copper content, the critical breakdown field strength (E/N)_cr appears in the temperature range below 3000K. Significantly reduced, but there is a certain increase in the temperature range above 3000K. In addition, this paper also found that as long as the copper vapor ratio and gas pressure are appropriate, the post-arc insulation breakdown characteristics of SF₆ can be significantly improved.

Keywords：SF₆ gas, copper vapor, dielectric breakdown characteristics, electron energy distribution function, critical breakdown electric field strength

目 录

摘要…………………………………………………………………………………… I

Abstract Ⅱ

第一章 绪论 1

1.1选题的背景及意义 1

1.2 国内外研究现状 2

1.2.1 国内研究现状 2

1.2.2 国外研究现状 3

1.3 本文主要研究内容 5

第二章 气体弧后绝缘击穿的原理 6

2.1气体弧后绝缘击穿的实验研究 6

2.2 气体绝缘击穿的理论研究 7

2.2.1电离过程 7

2.2.2吸附过程 8

2.3 玻尔兹曼方程的求解 8

2.4电子概率系数与输运系数 12

2.5折合临界击穿场强的计算流程 13

2.6本章小结 14

第三章 气体弧后绝缘击穿特性的计算 16

3.1 热态SF₆气体组分 16

3.2碰撞截面 17

3.2.1 SF₆气体的碰撞截面 17

3.2.2 SF₂气体的碰撞截面 18

3.2.3 CuS气体的碰撞截面 19

3.2.4 CuF与CuF₂气体的碰撞截面 19

3.3本章小结 20

第四章 SF₆在铜蒸气中绝缘击穿特性的分析 21

4.1 电子能量分布函数（EEDF） 21

4.2 约化电离系数、约化电子吸附系数和约化临界击穿场强 23

4.3 不同铜蒸汽浓度下绝缘气体击穿特性的比较 29

4.4 本章小结 30

第五章 结论与展望 32

5.1结论 32

5.2不足与展望 32

参考文献 34

致谢 36

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