【摘要】：局部放電檢測(cè)是電氣設(shè)備故障診斷最有效的方法之一,被廣泛應(yīng)用于電纜附件故障診斷。但是,由于背景噪聲的存在,尤其是白噪聲的存在使得局部放電在線檢測(cè)的靈敏度大大降低。白噪聲的頻率成分遍布整個(gè)頻域,時(shí)域波形也遍布整個(gè)時(shí)域,這使得去除局放信號(hào)中的白噪聲干擾成為局放信號(hào)去噪技術(shù)中的一個(gè)難點(diǎn)和熱點(diǎn)研究課題。基于以上論述,本文以電纜終端局部放電檢測(cè)為基礎(chǔ)提出了兩種局放信號(hào)去噪方法分別用以去除高信噪比和低信噪比下的白噪聲干擾。主要研究?jī)?nèi)容如下:(1)分析了電纜終端發(fā)生故障的主要原因;設(shè)計(jì)制作了 4種電纜終端典型缺陷模型作為本文試驗(yàn)部分的試驗(yàn)對(duì)象開展局部放電試驗(yàn);采集了 4種電纜終端典型缺陷的局放信號(hào)作為本文所提去噪方法的試驗(yàn)驗(yàn)證。(2)提出了一種基于峭度和時(shí)域能量的局放信號(hào)去噪方法,用以解決高信噪比下現(xiàn)有局放信號(hào)去噪方法計(jì)算速率慢、去噪后脈沖邊沿不清晰的問題。首先通過計(jì)算染噪局放信號(hào)峭度實(shí)現(xiàn)局放脈沖的定位,進(jìn)而確定局放脈沖峰值在整個(gè)數(shù)據(jù)窗中的位置以減小后續(xù)脈沖提取的計(jì)算量;其次通過分析白噪聲與局放脈沖信號(hào)的時(shí)域能量差異,確定時(shí)域能量閾值及對(duì)應(yīng)的時(shí)窗長(zhǎng)度;最后以脈沖峰值為中心采用時(shí)域能量搜索的方法向兩邊搜索脈沖的邊沿實(shí)現(xiàn)局部放電脈沖邊沿檢測(cè)及確定,進(jìn)而實(shí)現(xiàn)局部放電脈沖提取。(3)提出了一種局放信號(hào)自適應(yīng)稀疏分解去噪方法,同時(shí)構(gòu)造了與局放信號(hào)對(duì)應(yīng)的匹配原子庫(kù),用以提高局放信號(hào)去噪過程中MP算法的計(jì)算效率和去噪效果。基于信號(hào)快速譜峭度和S變換,迅速獲取局放信號(hào)時(shí)頻特性,其中包括中心頻率、帶寬、局放發(fā)生起始點(diǎn)和熄滅點(diǎn)的大概位置;利用局放信號(hào)的時(shí)頻特性優(yōu)化局放信號(hào)匹配原子庫(kù)的時(shí)頻參數(shù),在對(duì)染噪局放信號(hào)進(jìn)行MP計(jì)算時(shí)自適應(yīng)選擇少量原子進(jìn)行尋優(yōu)匹配;用各次迭代所得最佳匹配原子對(duì)原始局放脈沖信號(hào)進(jìn)行稀疏表示,達(dá)到局放信號(hào)去噪目的。仿真及試驗(yàn)表明,本文所提出的兩種局放信號(hào)去噪方法有效的解決了現(xiàn)有局放信號(hào)去噪方法去噪過程中所存在的去噪程序繁瑣、計(jì)算速率慢、去噪不徹底、去噪后波形畸變問題。
[Abstract]:Partial discharge detection is one of the most effective methods for fault diagnosis of electrical equipment and is widely used in cable accessory fault diagnosis. However, because of the background noise, especially the white noise, the sensitivity of PD on-line detection is greatly reduced. The frequency components of white noise are all over the frequency domain, and the waveform of time domain is all over the time domain, which makes the removal of white noise interference from partial discharge signal become a difficult and hot research topic in the denoising technology of partial discharge signal. Based on the above discussion, based on the partial discharge detection of cable terminal, two kinds of partial discharge signal denoising methods are proposed to remove white noise interference at high signal-to-noise ratio and low signal-to-noise ratio respectively. The main research contents are as follows: (1) the main causes of cable terminal failure are analyzed, and four typical defect models of cable terminal are designed and made as the test object of this paper to carry out partial discharge test. Four kinds of partial discharge signals with typical defects of cable terminals are collected as experimental verification of the denoising methods proposed in this paper. (2) A denoising method for partial discharge signals based on kurtosis and time domain energy is proposed. It is used to solve the problem of slow calculation speed and unclear pulse edge of existing partial discharge signal denoising methods under high SNR. Firstly, the location of partial discharge pulse is realized by calculating the kurtosis of local discharge signal, and then the position of peak value of partial discharge pulse in the whole data window is determined to reduce the computation amount of subsequent pulse extraction. Secondly, by analyzing the time domain energy difference between white noise and partial discharge pulse signal, the time domain energy threshold and the corresponding time window length are determined. Finally, using the time-domain energy search method to search the edge of the pulse on both sides, the detection and determination of the partial discharge pulse edge can be realized by taking the peak value of the pulse as the center. Then partial discharge pulse extraction is realized. (3) an adaptive sparse decomposition de-noising method for partial discharge signal is proposed, and a matching atom library corresponding to partial discharge signal is constructed. In order to improve the computational efficiency and denoising effect of MP algorithm in the process of partial discharge signal denoising. Based on the fast spectral kurtosis and S-transform, the time-frequency characteristics of PD signal are obtained, including the center frequency, bandwidth, the starting point of PD and the approximate position of extinguishing point. The time-frequency parameters of the partial discharge signal matching atom library are optimized by using the time-frequency characteristic of partial discharge signal, and a small number of atoms are adaptively selected for optimal matching when MP calculation is carried out on the noisy partial discharge signal. The original PD pulse signal is represented sparsely by the best matching atoms obtained from each iteration to achieve the purpose of de-noising the PD signal. The simulation and experiments show that the two methods proposed in this paper can effectively solve the problem that the existing partial discharge signal denoising methods are complicated in the process of de-noising, slow calculation rate and incomplete de-noising. Waveform distortion after denoising.
【學(xué)位授予單位】：西南石油大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TM855

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