摘 要

近年来，气体绝缘金属封闭输电线路(GIL)在全球范围内得到迅猛发展，其输电量大，损耗小，运输安装方便，安全可靠等突出的优势使其在领域内具有极高的竞争力。同时，GIL已经在实际生产中得到了较为广泛的应用，有些设备已经运行了较长的时间，其输电能力和安全性能已得到了实际印证。

截止现在，GIL的产品已经大致经过了三代的发展历史，目前选用较为广泛的绝缘气体是N₂/SF₆的混合气体，其在环保性和经济性上都要大大优于早期的纯净SF₆气体。

本文首先介绍了GIL的工作原理和特点，分析了选用N₂/SF₆作为绝缘气体的优势，然后介绍了其在国内外得到的发展与应用。

其次，根据气体放电的基本理论，分析了N₂/SF₆混合气体的放电原理，包括气体放电的过程和判定依据，使用计算的方法分析了混合气体的绝缘特性，研究了GIL内部电场场强的设计问题。

然后选用有限元分析软件COMSOL Multiphysics建立了1100kV 特高压交流GIL管道的仿真模型，首先介绍了有限元分析方法的原理，然后在静电场，电磁场和流场中对GIL仿真模型进行了分析，研究N₂/SF₆混合气体作为绝缘气体时其内部的场强，温度等物理量的分布。

关键字：气体绝缘金属封闭输电线路 SF₆/N₂混合气体 绝缘特性 有限元仿真

Abstract

In recently years, Gas Insulated Metal Enclosed Transmission Line(GIL) has been developed rapidly all around the world,it has many advantages:it can transmit large electricity with very small loss,it’s easy to transport and install the equipment,it works securely and reliably. As the above advantages,it’s highly competitive in the field.At the same time, GIL has been widely used in practical production,some devices have worked for a long time,the Transmission capability and safety function has been confirmed.

So far, GIL has gone through three generations of history,the mostly used insulating gas is the mixture of SF₆ and N₂,it is vastly superior to the pure SF₆ which was used early when it comes to the environment protecting and economic efficiency.

This paper introduces the operation principle and features of GIL,presents the superiority of the mixture of SF₆ and N₂,and suggests the development and application of GIL at home and abroad.

After that,according to the basic theory of gas discharge,the discharge principle of the mixture of SF₆ and N₂ is analyzed in this paper,including the process and determination basis of the gas discharge.The insulation characteristics of mixture gas is analyzed in calculation methods, the electric field intensity in the internal electric field of GIL is studied especially.

Then establish the simulation model of 1100kV UHV AC GIL pipeline by using the finite element analysis software COMSOL Multiphysics.Firstly, the principle of finite element analysis method is introduced, and then the GIL simulation model is analyzed in the electrostatic field, electromagnetic field and flow field.The distribution of the field strength, temperature quantities of N₂/SF₆ mixed gas is studied

Key words：GIL；Mixed gas of SF₆ and N₂；Insulation characteristics；Finite element simulation

目 录

第1章 绪论 1

1.1 GIL的特点和工作原理 1

1.1.1 GIL的特点 1

1.1.2 GIL的工作原理 2

1.2 SF₆/N₂混合气体作为绝缘气体的优势 3

1.3 GIL在国内外的发展与应用 4

1.4 本文主要研究内容 6

第2章 SF₆/N₂混合气体放电原理 7

2.1 气体放电理论 7

2.2 气体放电判定依据 7

2.3 SF₆/N₂混合气体气体放电过程 9

2.4 SF₆和N₂混合气体绝缘强度的计算 10

2.4.1 SF₆和N₂混合气体的临界击穿强度 10

2.4.2 SF₆和N₂混合气体在不均匀电场中的起始放电电压 13

2.5 SF₆和N₂混合气体不同混合比气体压力的计算 13

2.6 GIL内部电场场强设置 14

第3章 GIL仿真模型建立与计算 15

3.1 有限元分析法原理 15

3.2 物理场仿真分析的基础 16

3.3 GIL内部混合气体的处理方式 17

3.4 GIL三维仿真模型在静电场的仿真 18

3.5 GIL在电磁场中的稳态仿真 23

3.6 GIL在多物理场中的暂态仿真 26

3.7 GIL模型仿真结果分析 27

第4章 结论 28

参考文献 29

致 谢 31

第1章 绪论

1.1 GIL的特点和工作原理

1.1.1 GIL的特点

气体绝缘金属封闭输电线路GIL（Gas Insulated Metal Enclosed Transmission Line）是一种安全稳定，输电量大，损耗小，环境友好型的新型输电线路。