基于波形综合相对熵的谐振接地系统故障选线方法

发布时间：2018-01-19 06:14

本文关键词： 谐振接地系统暂态零序电流波形相似性直方图分解相对熵模糊核聚类 ATP-EMTP　出处：《福州大学》2014年硕士论文　论文类型：学位论文

【摘要】：我国中压配电网中性点主要采用小电流接地方式,包括中性点不接地、中性点经高阻接地、中性点经消弧线圈接地(又称谐振接地)。当谐振接地系统发生单相接地故障时,由于消弧线圈的补偿作用,系统故障电流微弱,电弧不稳定及一些随机因素,给故障选线造成很大的影响。与其他接地系统相比,谐振接地系统故障选线一直是配电网故障选线中的难点,进一步研究谐振接地系统故障选线方法具有重要的理论和实际意义。本文在总结了目前国内外各种选线方法的基本原理和优缺点的基础上,分析了谐振接地系统发生单相接地故障后的稳态、暂态过程及大过渡电阻对系统的影响。通过零序网络分析得出了故障后非故障线路间暂态零序电流的波形相似度大于非故障线路与故障线路间暂态零序电流的波形相似度的结论,提出了一种基于波形综合相对熵的谐振接地系统故障选线新方法。首先利用HHT良好的时频特性来更好地判断故障时刻,进而对故障后各线路暂态零序电流波形在时间轴及幅值轴上分区间,并做直方图分解,通过能体现状态差异的相对熵求取反映故障暂态零序电流极性信息的相对熵矩阵；其次考虑故障暂态零序电流波形的局部相似性及整体相似性,定义了包含故障暂态零序电流波形幅值信息的幅值矩阵,结合相对熵矩阵构造体现故障信息的综合相对熵矩阵,最后利用免阈值设定的模糊核聚类算法(KFCM)判别故障线路与非故障线路。此外,本文对电弧故障理论进行了研究,选取了符合实际运行状况的一次电弧模型,在验证电弧模型准确性的基础上,进一步分析了电弧特性及电弧接地故障。采用电磁暂态分析软件ATP-EMTP搭建谐振接地系统仿真模型,验证了在不同过渡电阻、不同故障初相角、不同线路故障、电弧接地故障、两点接地故障、电磁噪声干扰、断线故障、采样不同步、不同补偿度等条件下选线方法的准确性。大量仿真结果证明,所提出的故障选线方法准确可靠,具有一定的工程价值。
[Abstract]:The neutral point of the medium voltage distribution network in our country mainly adopts the small current earthing way, including the neutral point is not grounded, the neutral point is grounded through the high resistance. The neutral point is grounded by arc-suppression coil (also called resonant earthing). When the single-phase grounding fault occurs in the resonant grounding system, the fault current of the system is weak, the arc is unstable and some random factors occur because of the compensation action of the arc-suppression coil. Compared with other grounding systems, fault line selection of resonant grounding system is always the difficulty of fault line selection in distribution network. It is of great theoretical and practical significance to further study the fault line selection method of resonant grounding system. This paper summarizes the basic principles, advantages and disadvantages of all kinds of fault line selection methods at home and abroad. The steady state of resonant grounding system after single-phase grounding fault is analyzed. Transient process and the influence of large transient resistance on the system. Through the analysis of zero-sequence network, it is concluded that the waveform similarity of transient zero-sequence current between non-fault line and fault line is greater than that between non-fault line and fault line. Conclusion of shape similarity. A new method of fault line selection for resonant grounding system based on waveform synthesis relative entropy is proposed. Firstly, the good time-frequency characteristic of HHT is used to better judge the fault time. Then the transient zero-sequence current waveform of each line after fault is divided on the time axis and amplitude axis, and is decomposed by histogram. Through the relative entropy which can reflect the state difference, the relative entropy matrix which can reflect the transient zero-sequence current polarity information is obtained. Secondly, considering the local similarity and global similarity of fault transient zero-sequence current waveform, the amplitude matrix containing the amplitude information of fault transient zero-sequence current waveform is defined. Combined with the relative entropy matrix to construct the comprehensive relative entropy matrix which reflects the fault information. Finally, the threshold free fuzzy kernel clustering algorithm (KFCM) is used to distinguish the fault line from the non-fault line. In this paper, the arc fault theory is studied, and the primary arc model, which is in accordance with the actual operation condition, is selected, and the accuracy of the arc model is verified. The simulation model of resonant grounding system is built by using electromagnetic transient analysis software ATP-EMTP, which verifies the different transition resistance and different fault initial phase angle. The accuracy of different line fault, arc grounding fault, two-point grounding fault, electromagnetic noise interference, broken line fault, sampling out of sync, different compensation degree and so on. The proposed fault line selection method is accurate and reliable, and has certain engineering value.
【学位授予单位】：福州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM862

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