小电流接地系统单相接地选线算法研究及选线装置实现

发布时间：2018-03-07 07:39

本文选题：综合选线算法　切入点：单相接地　出处：《燕山大学》2014年硕士论文　论文类型：学位论文

【摘要】：小电流接地系统指中性点不接地或经消弧线圈接地的电力系统，电力系统采用这种中性点非有效接地方式的优点是供电可靠性高。在我国的6-66kV电网中，广泛采用中性点不接地或经消弧线圈接地的运行方式。单相接地故障在中、低压配电网中是非常频繁的，统计资料显示单相接地故障占中、低压配电线路故障的80%以上，且单相接地产生的间歇性弧光接地可能引起电弧接地过电压进而威胁系统的绝缘性能。所以对小电流接地电网单相接地故障的研究具有重要理论意义和现实意义。本文研究了典型小电流接地系统单相接地故障的故障特征和电压、电流变化规律，对当前比较成熟的几种故障选线算法理论及其各自适用的场合做了分析。基于小电流接地系统中接地故障复杂多变，而单一选线算法准确率低的实际情况，按照测度值构建一套综合选线判据，充分发挥有功功率法、首半波法和小波分析法等各种方法的优点，以提高装置的可靠性。选择电流幅值测度、电流相位测度、小波系数测度、首半波测度和有功分量测度来定量表示具体线路接地故障可能性的大小。针对中性点不接地和中线点经消弧线圈接地两种情况采用不同的测度组合形成一套综合判定逻辑，保证选线结果的准确度，提高该综合选线方案的适应性；增加了PT断线和铁磁谐振的判别程序，有效防止将这两种情况误判为单相接地故障。在对小波分析的基本原理进行阐述、分析的基础之上，按照小波分析的延拓、分解和重构这三个步骤，编写了小波分析的C语言代码并成功应用到DSP芯片上。此外，，为了满足对故障数据的记录和离线分析，本装置添加了将故障期间原始数据保存为COMTRADE标准格式文件的功能。根据实际情况需要，硬件方面本装置采用DSP+ARM多处理器构架，按照功能不同进行了模块化的设计，并采用插拔式安装方式，方便现场调试、检修。逻辑严密的软件流程设计、优秀的硬件抗干扰能力保证了该选线装置的整体性能和选线结果的准确性。
[Abstract]:The low current grounding system refers to the power system with neutral point ungrounded or grounded by arc-suppression coil. The advantage of this neutral non-effective grounding mode in power system is the high reliability of power supply. It is widely used that neutral point is ungrounded or grounded by arc-suppression coil. Single-phase grounding fault is very frequent in medium and low voltage distribution network. Statistics show that single-phase grounding fault is middle, and low-voltage distribution line fault is more than 80%. The intermittent arc grounding caused by single-phase grounding may cause overvoltage of arc grounding and threaten the insulation performance of the system. Therefore, the study of single-phase grounding fault in low-current grounding power network has important theoretical and practical significance. In this paper, the fault characteristics and the variation of voltage and current of a typical single-phase grounding fault in a small current earthing system are studied. In this paper, several mature fault line selection algorithms and their respective applications are analyzed. Based on the fact that grounding fault is complex and changeable in small current grounding system, and the accuracy of single line selection algorithm is low, In order to improve the reliability of the device, a set of comprehensive line selection criteria is constructed according to the measurement value, and the advantages of active power method, first half wave method and wavelet analysis are fully utilized. Select current amplitude measure, current phase measure, wavelet coefficient measure, The first half wave measure and active power component measure are used to quantitatively express the probability of grounding fault of a specific line. In the case of neutral ungrounded and neutral point grounded by arc-suppression coil, a set of comprehensive decision logic is formed by combining different measures. The accuracy of the line selection results is guaranteed, the adaptability of the comprehensive line selection scheme is improved, and the discrimination program of PT breaking line and ferromagnetic resonance is added to effectively prevent these two cases from being misjudged as single-phase grounding fault. On the basis of expatiating the basic principle of wavelet analysis, according to the three steps of continuation, decomposition and reconstruction of wavelet analysis, the C language code of wavelet analysis is written and successfully applied to DSP chip. In order to record and analyze the fault data off-line, the device adds the function of saving the original data during the fault as COMTRADE standard format file. According to the actual situation, the hardware of the device adopts DSP ARM multiprocessor architecture, modularized design according to different functions, and adopts plugged type installation mode, which is convenient for field debugging, overhaul and logical design of software flow. Excellent hardware anti-jamming ability ensures the overall performance of the line selection device and the accuracy of the line selection results.
【学位授予单位】：燕山大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM862

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