楊秋玉 阮江軍 黃道春 邱志斌 莊志堅(jiān)
摘 要:針對高壓斷路器分、合閘動作過程中產(chǎn)生的振動信號持續(xù)時間短暫及強(qiáng)烈的非線性非平穩(wěn)性,導(dǎo)致的特征提取困難問題,提出一種變分模態(tài)分解(VMD)-希爾伯特(Hilbert)邊際譜能量熵,及支持向量機(jī)(SVM)的高壓斷路器振動信號組合特征提取和機(jī)械故障診斷方法。采用VMD對高壓斷路器振動信號進(jìn)行分解,得到一系列反映振動信號局部特性的本征模態(tài)函數(shù)(IMF);對IMF進(jìn)行Hilbert變換,并求取對高壓斷路器機(jī)械狀態(tài)變化敏感的Hilbert邊際譜能量熵作為特征向量;將特征向量輸入到SVM分類器,實(shí)現(xiàn)高壓斷路器機(jī)械故障的智能診斷。試驗(yàn)結(jié)果表明:該方法能夠準(zhǔn)確識別高壓斷路器的常見機(jī)械故障類型,具有一定的工程應(yīng)用價值。
關(guān)鍵詞:高壓斷路器;變分模態(tài)分解;希爾伯特邊際譜;能量熵;支持向量機(jī);機(jī)械故障識別
DOI:10.15938/j.emc.2020.03.002
中圖分類號:TM 561文獻(xiàn)標(biāo)志碼:A文章編號:1007-449X(2020)03-0011-09
Abstract:In this paper, a feature extraction method and fault diagnosis for high voltage circuit breakers (HVCBs) is presented and discussed. The vibration signals are nonlinear and timevarying since the complicated structure and extremely fast operation of HVCBs, which makes the extraction and selection of sensitive features for fault diagnosis difficult. Therefore, it is of vital importance to explore a new vibration feature extraction algorithm to improve the accuracy of fault diagnosis for HVCBs. A combination feature extraction method based on variational mode decomposition (VMD) and Hilbert marginal spectrum energy entropy, and support vector machine (SVM) for the diagnosis of HVCBs mechanical condition is presented and clearly discussed. Vibration signals were decomposed into several intrinsic mode functions (IMFs) by using VMD. Marginal spectral energy entropies of IMFs (which vary with different fault types of HVCB) were obtained and served as feature vectors for the SVM classifier for the diagnosis of HVCB. Experimental results indicate that the proposed method can accurately identify the common mechanical faults of HVCB and has potential of practical application.
Keywords:high voltage circuit breakers; variational mode decomposition; Hilbert marginal spectrum; energy entropy; support vector machine; mechanical fault detection
0 引 言
高壓斷路器的可靠性對于保障電力系統(tǒng)的安全穩(wěn)定運(yùn)行具有重要的作用。運(yùn)行實(shí)踐表明,機(jī)械故障是導(dǎo)致高壓斷路器故障的主要原因。近年來,對高壓斷路器機(jī)械故障診斷的研究越來越多,一些研究成果也已用于實(shí)際工程,其中,基于振動信號的高壓斷路器機(jī)械故障診斷技術(shù)越來越受到人們的關(guān)注[1-3]。
高壓斷路器分、合閘動作時產(chǎn)生的振動信號蘊(yùn)含著豐富、重要的高壓斷路器狀態(tài)信息[4-6]。由于高壓斷路器動作時間極短(常常是幾十毫秒)、各運(yùn)動件之間強(qiáng)烈碰撞沖擊等特點(diǎn)質(zhì),使得其振動信號具有時域時間短、頻域分布寬、強(qiáng)烈的非線性非平穩(wěn)性。所以,一方面,對傳感器的性能提出了更高的要求:傳感器必須具有足夠高的采樣精確度,且頻響范圍及量程應(yīng)足夠大;另一方面,對振動信號的處理也提出了更高的要求,傳統(tǒng)的信號處理方法不能有效提取高壓斷路器這種具有強(qiáng)沖擊時變特性振動信號的關(guān)鍵信息。
針對高壓斷路器振動信號的特殊性,時頻分析方法無疑是較適合的,因此,越來越多的時頻分析方法被用于分析高壓斷路器的振動信號。如小波變換[7-9]、經(jīng)驗(yàn)?zāi)B(tài)分解[10-12](empirical mode decomposition,EMD)。實(shí)際上,小波變換的本質(zhì)還是一種傅里葉變換,存在信號能量泄漏、基函數(shù)選擇等問題,且不具備自適應(yīng)性。EMD是一種可以根據(jù)信號自身特點(diǎn)進(jìn)行自適應(yīng)多分辨率分解的信號分析方法,但其在分解過程中容易產(chǎn)生模態(tài)混疊、本征模態(tài)函數(shù)(intrinsic mode function,IMF)篩分停止條件和端點(diǎn)效應(yīng)等問題[13-14]。而變分模態(tài)分解[15-17](variational mode decomposition,VMD)通過尋找約束變分模型最優(yōu)解實(shí)現(xiàn)信號的分解,各IMF分量中心頻率和帶寬不斷交替迭代更新,實(shí)現(xiàn)信號頻帶的自適應(yīng)分解。VMD方法克服了EMD方法的諸多缺陷(如模態(tài)混疊等),大大提高信號分解的準(zhǔn)確性。振動信號經(jīng)VMD處理得到一系列反映振動信號局部特性的本征模態(tài)函數(shù)(IMF);IMF通過希爾伯特(Hilbert)變換可更有效、更真實(shí)地獲得振動信號中所含的重要信息,即Hilbert譜(Hilbert譜可精確地描述信號幅值在整個頻段上隨時間和頻率的變化規(guī)律)。
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(編輯:賈志超)