10kV输电线接地故障仿真平台

电气自动化论文编号:ZD788  论文字数:17444,页数:53  有开题报告和任务书

 目    录
1 第一章绪论 1
1.1 课题背景 1
1.2 电力配电网故障概述 1
1.3 10kV输电线在电力系统中的应用 2
1.4 国外研究现状 2
1.5 本章小结 3
2 第二章中性点不接地系统 5
2.1 电力系统的各种接地方式介绍 5
2.1.1 中性点直接接地 5
2.1.2 中性点不接地 6
2.1.3 经消弧线圈接地方式 6
2.1.4 中性点经电阻接地方式 7
2.2 各种接地方式的应用情况 8
2.3 中性点不接地系统构成 9
2.3.1 中性点不接地系统的优缺点 9
2.3.2 中性点不接地系统正常运行时的对地电容电流 10
2.3.3 中性点不接地系统单相故障的特征分析 12
2.4 电力系统中的谐波 19
2.4.1 电力系统中谐波的来源 19
2.4.2 谐波的危害 19
2.5 本章小结 21
3 第三章小电流接地系统单相接地故障仿真 23
3.1 仿真工具的选择 23
3.1.1 仿真工具的比较 23
3.1.2 MATLAB的认知 26
3.2 仿真实验系统 28
3.2.1 各元件的MATLAB建模 28
3.3 基于MATLAB的小电流接地系统模型 32
3.4 仿真参数设置 32
3.5 故障仿真 33
3.5.1 单相接地故障的仿真理论基础验证 34
3.5.2 过渡电阻的大小和零序电流的关系 38
3.5.3 故障位置对电压电流的影响 41
3.6 本章小结 44
4 结束语 45
4.1 全文结论： 45
5 参考文献 47
6 致谢 51

中文摘要

 在我国低压配电网大都采用中性点不接地方式运行，在分支繁多、接线复杂的树状配电网中，单相接地故障是发生机率最高的一种故障。虽然发生单相接地故障，但线路的线电压不变，对负荷连续供电没有多大影响，所以规程允许中性点不接地系统在发生单相接地故障后继续运行1～2 h，不必立即跳闸。但是单相接地后，其他两相非故障相电压升高倍，尤其是弧光引起的过电压极易造成两相或三相短路事故，长时间弧光电流引起局部过热，则可能导致架空线路烧毁，所以应迅速查找并排除接地点，提高系统的供电可靠性。由于单相接地故障情况复杂，接地电流小，给单相接地故障的探测带来了很大的难度。
 本文详细介绍了中性点不接地系统的特点，利用MATLAB构建一个10kV的中性点不接地的配电系统，进行故障仿真实验，并对各种故障情况作了大量的仿真，充分研究了10kV接地故障的各种特点,因此，本文所得的结论对与中性点不接地系统发生单相接地短路的监测和故障排除具有重要的参考价值。
关键词：单相接地故障，中性点不接地系统，故障相，MATLAB仿真软件

Abstract

 Neutral non-effectively grounded systems and resonant grounded systems are widely adopted in power distribution networks in China, and the phase-to-earth fault happens most frequently in power distribution networks. Since the line voltage is still symmetrical under fault conditions, the systems can keep operating for one or two hours. However long-time earthing operation will result in two-point, more seriously, multipoint earthing fault as well as ground arcing fault caused over voltage. It will destroy the systematic safe operation. Thus how to detect the fault line quickly and accurately is an important issue in power system protective relaying, which has not been solved completely.
 This article introduced in detail the neutral point earth system characteristic, does not construct the electrical power distribution system using MATLAB which 10kV the neutral point does not earth, carries on the breakdown simulation experiment, and has made the massive simulations to each kind of breakdown situation, has fully studied 10kV earth fault each kind of characteristic, therefore, the this article obtained conclusion to does not have the monitor and the trouble shooting with the neutral point earth system which the single-phase earth short-circuits has the important reference value.
Key words：Single-phase earth fault, neutral point earth system, breakdown, MATLAB simulation software