本文關鍵詞： 配電網 暫態(tài)零序電流 伸縮變換 相平面 模糊K均值聚類　出處：《福州大學》2014年碩士論文　論文類型：學位論文

【摘要】：我國配電網普遍采用小電流接地方式,即中性點不接地方式和中性點經消弧線圈接地方式。在小電流接地方式中,單相接地故障的概率很高,一般占總故障的80%以上。當小電流接地系統(tǒng)發(fā)生單相接地故障時,由于接地電流較小,且故障后三相電壓仍保持對稱關系,不會影響負荷的持續(xù)供電,在一定程度上可以提高電力系統(tǒng)的供電可靠性。由于小電流接地系統(tǒng)發(fā)生單相接地故障的情況復雜多變、故障電流較微弱,且常伴有間歇性電弧,以及受線路結構參數(shù)、互感器非線性特性、電磁干擾等影響,故障線路零序電流的頻譜特性、能量分布和衰減特性有著很大的差異,一直缺乏可靠的單相接地故障選線方法,其接地選線問題仍未得到很好解決。本文總結了配電線路單相接地故障選線方法,分析了穩(wěn)態(tài)量選線方法的不足之處,說明利用暫態(tài)量進行單相接地故障選線的優(yōu)勢。通過對諧振接地系統(tǒng)暫、穩(wěn)態(tài)零序電流的分析,指出非故障線路間暫態(tài)零序電流波形的相似性強于故障線路與非故障線路暫態(tài)零序電流波形的相似性,基于此提出一種基于波形伸縮變換和模糊K均值聚類的配電線路單相接地選線新方法。選取故障后半個工頻周期的暫態(tài)零序電流進行處理,運用相平面分析的方法對暫態(tài)零序電流作分段相平面變換,用另一種形態(tài)來表征暫態(tài)零序電流波形；然后利用能夠綜合反應幅值和極性信息的歐氏距離來構造各線路的特征量,并形成特征矩陣。結合系統(tǒng)各饋線只需分為故障線路和非故障線路兩類的特點,利用模糊K均值聚類的方法將特征矩陣分為兩類,則自成一類的線路即為故障線路。在暫態(tài)零序電流信號的處理上,本文首次提出了暫態(tài)零序電流波形伸縮變換理論,伸縮變換處理較好地解決了非故障線路間暫態(tài)零序電流數(shù)值型屬性大小不一的影響,提高了非故障線路間暫態(tài)零序電流波形的相似度,提高了選線的裕度。利用ATP電磁暫態(tài)仿真軟件搭建10kV諧振接地系統(tǒng)的仿真模型,對不同接地電阻、不同接地相角、不同故障線路、不同故障位置、不同接地類型等單相接地故障情況進行大量的仿真,仿真結果表明本文所提方法均能正確選線。綜合考慮工程應用中可能存在的影響因素,文中對零序電流互感器、消弧線圈補償度、電磁噪聲、采樣不同步、間歇性電弧接地等可能存在的影響因素進行仿真,仿真結果表明該方法能在以上干擾條件下正確選線。大量仿真表明,本文所提單相接地故障選線方法可靠性高、選線裕度高、適應性強,具有一定的工程應用價值。
[Abstract]:In our distribution network, small current grounding is widely used, that is, neutral ungrounded mode and neutral point grounding through arc suppression coil. In the low current grounding mode, the probability of single-phase grounding fault is very high. Generally speaking, it accounts for more than 80% of the total faults. When a single-phase grounding fault occurs in a small current earthing system, the three-phase voltage still maintains a symmetrical relationship because of the small grounding current, which will not affect the continuous power supply of the load. To a certain extent, the reliability of power supply can be improved. Because of the complex and changeable condition of single-phase grounding fault in small current grounding system, the fault current is weak, and it is often accompanied by intermittent arc, as well as the structural parameters of the line. Due to the influence of nonlinear characteristics of transformer, electromagnetic interference and so on, the spectrum characteristics, energy distribution and attenuation characteristics of zero sequence current of fault lines are very different, and there is a lack of reliable method of fault line selection for single-phase grounding. The problem of grounding line selection has not been solved well. This paper summarizes the method of single-phase grounding fault line selection for distribution lines, and analyzes the shortcomings of the steady-state line selection method. The advantages of single phase grounding fault line selection using transient parameters are explained. Through the analysis of transient and steady zero sequence current of resonant grounding system, It is pointed out that the similarity of transient zero-sequence current waveforms between non-fault lines is stronger than that between fault lines and non-fault lines. Based on this, a new method of single-phase grounding line selection for distribution line based on waveform expansion transformation and fuzzy K-means clustering is proposed. The transient zero sequence current of half power frequency period after fault is selected for processing. The phase plane analysis method is used to transform the transient zero-sequence current into a piecewise phase-plane transform, and another form is used to characterize the transient zero-sequence current waveform, and then the Euclidean distance, which can synthesize the response amplitude and the polar information, is used to construct the characteristic quantities of each line. According to the characteristics of each feeder of the system, it can be divided into two categories by using fuzzy K-means clustering method, which only need to be divided into fault line and non-fault line, and the method of fuzzy K-means clustering is used to divide the feature matrix into two categories. In the processing of transient zero-sequence current signal, the theory of transient zero-sequence current waveform scaling is proposed for the first time. The scalable transformation can solve the influence of different values of transient zero-sequence current between non-fault lines, and improve the similarity of transient zero-sequence current waveform between non-fault lines. The simulation model of 10 kV resonant grounding system is built by using ATP electromagnetic transient simulation software. For different grounding resistance, different grounding phase angle, different fault line, different fault location, different grounding resistance, different grounding phase angle, different fault line, different fault location, different grounding resistance, different grounding phase angle, different fault line, different fault location, A large number of simulations have been carried out on single-phase grounding faults such as different grounding types. The simulation results show that all the methods proposed in this paper can correctly select lines. Considering the possible influence factors in engineering application, the zero sequence current transformer is discussed in this paper. The influence factors, such as compensation degree of arc suppression coil, electromagnetic noise, asynchronous sampling and intermittent arc grounding, are simulated. The simulation results show that the method can correctly select the line under the above interference conditions. The method proposed in this paper has the advantages of high reliability, high margin of line selection, strong adaptability, and has certain engineering application value.
【學位授予單位】：福州大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TM862

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