谐振接地系统单相接地暂态特征量聚类选线

发布时间：2019-02-14 14:03

【摘要】：谐振接地系统永久性单相接地故障时,线电压对称,规程允许继续运行1-2h,为防止因非故障相电压升高、绝缘弱化而导致故障扩大,必须尽快准确检出故障线路并切除；但此时故障电流微弱,故障暂态零序电流的频谱特性、能量分布及衰减特性在线路结构参数、互感器非线性特性、电磁干扰等因素影响下存在很大的差异,其选线问题长期以来未能得到很好解决。因此,有必要深入研究谐振接地系统单相接地故障选线。采用比故障稳态量大几倍甚至几十倍的故障暂态量进行选线保护是近年来该领域的研究热点。本文系统地概述了目前谐振接地系统的暂态量选线方法、暂态量选线研究现状以及故障选线方法存在的问题。在深入分析谐振接地系统发生单相接地故障时,故障线路与非故障线路暂态零序电流波形存在差异性原因的基础上,提出了一种故障选线新方法—谐振接地系统单相接地暂态特征量聚类选线法,通过增加进线暂态零序电流的检测解决母线故障选线问题。通过HHT带通滤波构造的时频矩阵,完备地描述了信号在各个频带下的时频特征,包含了表征信号本质特征的局部化信息。对时频矩阵做奇异值分解,由于奇异值是矩阵较为稳定的代数特征,具有良好的鲁棒性和泛化能力,能够适应谐振接地系统单相接地故障时各种复杂的情况；对各时频矩阵奇异值做模糊C均值聚类可将故障线路和非故障线路分类,在无需设置阈值的情况下选出故障线路。本文详细介绍了HHT数学理论、HHT带通滤波方法、奇异值分解理论及模糊C均值聚类算法。用ATP-EMTP搭建10kV谐振接地系统仿真模型,对系统中各个模块的建模做了详细的说明并验证模块性能,更加准确地模拟谐振接地系统发生单相接地故障的状态,从而获得接近真实故障情况的相关数据。对5种典型故障和其他故障情况包括电弧故障、噪声干扰、不同过补偿度、线路末端高阻接地、两点接地故障、采样不同步、短线路故障和不同线路数目等,做了大量的仿真实验,选线结果表明本文故障选线算法适应性好,选线准确可靠,具有一定的工程参考价值。
[Abstract]:In the case of permanent single-phase grounding fault of resonant grounding system, the line voltage is symmetrical, and the regulation allows to continue to run for 1-2h. in order to prevent the fault expansion caused by the increase of non-fault phase voltage and the weakening of insulation, the fault line must be accurately detected and excised as soon as possible. However, the frequency spectrum, energy distribution and attenuation characteristics of the transient zero-sequence current are different from each other under the influence of the circuit structure parameters, the nonlinear characteristics of the transformer and the electromagnetic interference, etc. The problem of route selection has not been solved well for a long time. Therefore, it is necessary to study the single-phase grounding fault line selection of resonant grounding system. In recent years, it is a research hotspot in this field to use fault transient quantity which is several times or even tens times larger than the steady state of the fault to detect the fault line protection. In this paper, the transient line selection method of resonant grounding system, the research status of transient line selection and the problems of fault line selection are systematically summarized. On the basis of deep analysis of the difference of transient zero-sequence current waveform between fault line and non-fault line when single-phase grounding fault occurs in resonant grounding system, the reason of the difference between the transient zero sequence current waveform of fault line and non-fault line is analyzed. In this paper, a new method of fault line selection, single phase earthing transient characteristic quantity clustering method, is proposed. The problem of bus fault line selection is solved by increasing the transient zero sequence current. The time-frequency matrix constructed by HHT bandpass filter is used to describe the time-frequency characteristics of the signal in every frequency band, and the localization information is included to characterize the essential characteristics of the signal. Because singular value is the stable algebraic characteristic of matrix, it has good robustness and generalization ability, and can adapt to various complicated cases of single-phase grounding fault of resonant grounding system. Fault lines and non-fault lines can be classified by fuzzy C-means clustering for singular values of time-frequency matrices, and fault lines can be selected without setting threshold. In this paper, HHT mathematical theory, HHT bandpass filtering method, singular value decomposition theory and fuzzy C-means clustering algorithm are introduced in detail. The simulation model of 10kV resonant grounding system is built by using ATP-EMTP. The modeling of each module in the system is explained in detail and the performance of the module is verified, and the state of single-phase grounding fault in resonant grounding system is more accurately simulated. Thus, the relevant data are obtained which are close to the real fault situation. For five kinds of typical faults and other faults, including arc fault, noise interference, different degree of overcompensation, high resistance earthing at the end of the line, two point grounding fault, sampling out of sync, short line fault and different number of lines, etc. A large number of simulation experiments have been done, and the results of line selection show that the fault line selection algorithm in this paper has good adaptability, accurate and reliable line selection, and has certain engineering reference 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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