基于电气几何模型的线路绕击防护性能研究
1
中文摘要
本文对绕击事故的形成原因与绕击率的计算方法进行了探讨，对输电线路雷电屏蔽的经典电气几何模型和改进电气几何模型进行了研究和对比。在分析和研究了输电线路屏蔽系统的组成、影响输电线路雷击绕击率的主要因素后，综合国内外研究成果的情况下，对经典电气几何模型进行了三点改进，并建立了考虑地形、杆塔高度影响的改进电气几何模型。计算中采用IEEE 推荐的计算击穿距离的公式，引入击距系数 k 来描述雷电击中输电线路和雷电击中地面击穿强度的不同，用暴露弧段来计算雷电绕击率和绕击跳闸率。并用MATLAB编制了基于改进电气几何模型的计算输电线路绕击率及绕击跳闸率的软件。该计算软件可以正确反映杆塔结构、地形对绕击率的影响，在输入雷电流大小、杆塔高度、输电线路高度、地面倾角、导线间距、保护角数值后可以得出绕击率和绕击跳闸率的计算数值。
计算结果表明，当地面倾角增大、避雷线保护角增大、杆塔高度增大时绕击率和绕击跳闸率会随之增大。
关键字：绕击、电气几何模型、输电线路
2
Abstract
In this paper, the reasons for shielding failure are discussed. The ways of getting the shielding failure rate are compared and the best is the electric geometrical model (EGM).The disadvantages of EGM is also discussed and a improved electric geometrical model is proposed based productions from both inland and foreign papers. The improved EGM is improved in three aspects .With such model the effect of tower structure, lightning current amplitude, ground angle and shielding angle can be taken into account. In the improved model , ‘strike distance’ is calculated with the expression recommended by IEEE, a coefficient k is introduced to describe the difference of elect- ric intensity between lightning stroke on the transmission line and the ground, and the ‘uncovered distance’ is adopted to calculate shielding failure flashover rate.
A matlab program is designed to carry out this model, and with the input of lighting current amplitude, height of the tower and transmission line, the shielding angle and the ground angle, the shielding failure rate and shielding failure of trip-out rate of transmission line can be calculated and outputted .
The results show that the flashover rate increases with the increase of the ground angle, protection angle and the height of the tower.
Key words: electric geometrical model (EGM) ; shielding failure ; transmission line
3
目录
摘 要 ...................................................... 错误！未定义书签。 Abstract .................................................... 错误！未定义书签。 第一章 引言.................................................................. 4
1.1 研究背景 .............................................................. 4 1.2 目前国内常用的几种绕击计算方法 ........................................ 4 1.3 经典电气几何模型的优点与缺点 .......................................... 6 1.4 本文对于经典电气几何模型的改进 ........................................ 6 1.5 本文所做的主要工作 .................................................... 6 第二章 设计流程及基本理论 ..................................................... 8
2.1 设计流程 .............................................................. 8 2.2 改进电气几何模型的计算步骤及公式 ...................................... 8 2.3 程序分块 ............................................................. 10 第三章 程序框图及源程序 ...................................................... 11
3.1 程序框图 ............................................................. 11 3.2 分块程序编辑 ......................................................... 13 3.3 源程序 ............................................................... 16 3.4 测试数据及其结果 ..................................................... 19 3.5 Pa-h，Pa-θs，Pa-θg测试图形 ......................................... 20 结 论 ...................................................................... 22 参考文献 .................................................................... 24 附录 ........................................................................ 25
源程序 ................................................................... 25 致 谢 ...................................................................... 44 翻译原文及其译文 ............................................................. 45
4