基于小波变换的配电网单相接地故障定位研究及应用

论文编号:TX059       论文字数:44691,页数:83

摘  要
随着社会经济的发展，对电力需求日益增长，同时对供电质量和配电自动化的水平提出了更高的要求。配电网大多采用小电流接地系统，单相接地故障定位研究一直是电力系统的研究热点。
小波变换是近年来发展壮大起来的应用数学领域的一个分支，其在电力系统中也得到了广泛的应用。作为一种全新的时频分析方法，它可以随着信号频率高低的变化自适应地调节其时频窗的形状，被认为是暂态信号的理想分析工具。通过对单相接地故障后的稳态和暂态过程分析并比较后得出结论，暂态过程携带丰富的故障信息，小波分析方法完全有能力提取出这些“隐藏”的信息。故障定位包含两个部分，一是故障选线，即在各条出线中选出发生故障的线路；二是故障测距，即准确测量故障线路的故障点位置。
文章提出了一种新的选线判据，它利用各线路零序电流暂态分量的小波变换的细节分量，依据在特征尺度下各值的大小及极性判断出故障线路；并通过故障发生后对线路中电流行波的分析，提出了基于行波法的故障选线判据，补充了前一种选线方法的单一与不足，重要的是与后续的基于电流行波的故障测距在理论上达到一致性。文章对利用行波法进行故障测距进行了尝试，利用小波变换模极大值检测理论，检测行波到达时刻，实现故障测距。
经过大量仿真试验验证了选线判据与测距判据的有效性和准确性，并对故障定位系统装置研制进行了尝试性的总体结构设计和软件设计，提出了基于Matcom与Visual C++相结合的软件设计方法。

关键词：配电网 单相接地故障 故障定位 小波变换 故障选线 故障测距

Abstract
With the development of society and economy, the demand for power supply and its ability has increased rapidly in recent years. Most of power distribution network system adopts the small current neutral grounding system. The research of single phase-to-earth fault location is the focus in this field nowadays.
Wavelet transform is a new and promising theory in mathematics, and it has an extensive application in the power system now. It has been proved to be very efficient for transient signal analysis. According to a set of damped oscillations named “wavelets”, it builds a new representation for the analyzed signal. Thought analyzing the characters of the steady signal and the transient signal after the single phase-to-earth fault occurring, we draw a conclusion that the transient signal provided with the important fault info. According to the wavelet analysis, we can find out those “hidden” info. Fault location includes two parts. One is fault line selection, the other is fault distance detection.
The paper brings forward a bran-new approach for fault line selection. By transforming the zero-sequence current of fault signal, we can tell easily on which line the faults have occurred. The major point here is to compare the maximum points of the details, either their magnitudes or directions can be used to identify the fault line. Moreover, by analyzing the traveling wave after single phase-to-earth fault occurred, we put forward another approach based on current traveling wave for fault line selection. This approach is powerfully complementary for the former one, and the more important point is it achieves a theoretic identity with fault distance detection arithmetic that putting forward in the paper. The fault distance detection principle that utilizes traveling wave appears in the small-current-grounding system. Using the powerful function of wavelet in the face of singular detection, the time that the traveling wave crest arrives is detected and the fault distance detection is realized.
By plenty of simulation test, the results show that the methods putting forward in the paper are efficient and reliable. Moreover, the paper attempts to design an equipment of Fault-location system, and it brings forward a software designing method by using Matcom and Visual C++.

Key words: Power distribution network, Single phase-to-earth fault, Fault location, Wavelet transform, Fault line selection, Fault distance detection

目  录

摘  要 II
Abstract   III
目  录   V
第1章 绪  论   1
1.1 问题的提出及研究意义   1
1.2 国内外配电网单相接地故障定位的研究及应用现状[3  2
1.2.1 国外研究现状   2
1.2.2 国内研究现状   2
1.3 寻求新的研究方法   3
1.4 论文的主要工作   4
第2章 配电网单相接地故障分析   5
2.1 中性点接地方式概述[4]   5
2.2 中性点不接地系统故障分析[5]   6
2.2.1 故障稳态特征分析   6
2.2.2 故障暂态特征分析   8
2.3 中性点经消弧线圈接地故障分析[6]   9
2.3.1 故障稳态特征分析  9
2.3.2 故障暂态特征分析   11
2.4 通过分析得到的结论   14
2.4.1 稳态故障特征分析结论   14
2.4.2 暂态故障特征分析结论   14
2.5 系统建模与仿真平台   15
2.6 本章小结   17
第3章 小波变换理论及在电力系统中的应用   18
3.1 小波变换的数学表达[10]   18
3.2 从信号分析的过程理解小波变换  20
3.3 离散小波变换   22
3.3.1 离散小波变换与多分辨率分析算法的描述   22
3.3.2 引入实例解析Mallat算法   25
3.4 基于小波变换的信号奇异性检测   26
3.4.1 小波变换模极大值点与信号突变点之间的关系[15]   27
3.4.2 引入实例解析信号的奇异性检测  28
3.5 小波分析在电力系统中的应用综述  29
3.6 本章小结   31
第4章 基于小波变换的配电网单相接地故障选线研究   32
4.1 从故障选线的角度分析单相接地故障特征  32
4.2 故障选线原理的小波表示——选线算法   33
4.2.1 已往选线算法的总结   33
4.2.2 提出选线步骤和选线算法   34
4.3 选线算法分析   36
4.3.1 小波基的选取[24]   36
4.3.2 分解尺度的确定   37
4.3.3 故障选线启动量的选择   37
4.4 仿真实例分析  38
4.4.1 母线故障的仿真   38
4.4.2 中性点不接地系统故障选线仿真   40
4.4.3 中性点经消弧线圈接地系统故障选线仿真  42
4.5 从“行波”的角度理解故障选线  44
4.5.1 “行波”的来源[26  44
4.5.2 行波的波速与波阻抗  46
4.5.3 行波的物理解释[30]   48
4.5.4 从行波分析故障选线  48
4.6 本章小结  49
第5章 基于小波变换的配电网单相接地故障测距研究  51
5.1 选取一种有效测距方法  51
5.1.1 阻抗法测距概述  51
5.1.2 行波法测距概述   53
5.2 行波测距的理论基础   55
5.2.1 电流行波的故障特征  55
5.2.2 行波信号的测量与采集  57
5.3 暂态电流行波测距的小波表示——测距算法  57
5.3.1 行波的小波表示  57
5.3.2 引入实例分析电流行波的小波表示  58
5.3.3 基于电流行波的故障测距算法   60 
5.4 测距算法分析  61
5.4.1 波速度的选择  61
5.4.2 架空线与电缆交叉连接情况下的测  61
5.4.3 行波在母线处的反射与透射   62
5.4.4 对端母线反射波的影响   62
5.5 仿真实例分析   63
5.6 本章小结   64
第6章 配电网单相接地故障定位系统的应用研究  65
6.1 系统的总体结构实现研究  65
6.2 故障数据处理的软件实现研究  68
6.3 本章小结   70
结论与展望   71
参考文献   72
致  谢   76