發(fā)布時(shí)間：2018-02-25 04:06

  本文關(guān)鍵詞： 到達(dá)時(shí)間差定位技術(shù) 半定規(guī)劃理論 半定松弛方法 秩-1松弛 逐次逼近方法　出處：《重慶大學(xué)》2014年博士論文　論文類型：學(xué)位論文

【摘要】：局部放電（Partial Discharge, PD）是電氣設(shè)備內(nèi)部發(fā)生絕緣缺陷時(shí)在局部范圍內(nèi)產(chǎn)生的一種放電現(xiàn)象。電力變壓器的多數(shù)故障是由內(nèi)部絕緣缺陷產(chǎn)生的PD，在運(yùn)行電壓下的不斷加劇和發(fā)展，最終造成設(shè)備整體絕緣性能喪失而引發(fā)故障。這類似于“腫瘤”的發(fā)展過程與最終危害一樣，PD在本領(lǐng)域有“絕緣腫瘤”之稱。所謂“絕緣腫瘤”，具體地講就是由于設(shè)備內(nèi)部初期絕緣缺陷產(chǎn)生PD，可能導(dǎo)致局部高能電磁脈沖對(duì)裝備內(nèi)部絕緣材料的加速損傷，若不及早發(fā)現(xiàn)并加以“治理”，它會(huì)由弱變強(qiáng)、由局部到整體，最終可能導(dǎo)致絕緣材料完全喪失絕緣能力，致使裝備發(fā)生絕緣擊穿性損壞，進(jìn)而引發(fā)電網(wǎng)停電事故。因此，對(duì)電力變壓器內(nèi)部產(chǎn)生的PD源進(jìn)行快速、準(zhǔn)確定位監(jiān)測(cè)，不僅是保證設(shè)備安全運(yùn)行的有效方法之一，也是根據(jù)絕緣故障部位對(duì)設(shè)備安全運(yùn)行帶來的危險(xiǎn)程度來制定有針對(duì)性的檢修策略的重要依據(jù)之一。 特高頻（Ultra High Frequency, UHF）檢測(cè)技術(shù)具有靈敏度高、抗干擾能力強(qiáng)等優(yōu)點(diǎn)，將其應(yīng)用于電力變壓器內(nèi)部PD源的定位，一直是本領(lǐng)域關(guān)注的熱點(diǎn)問題之一。但如何根據(jù)UHF PD實(shí)現(xiàn)準(zhǔn)確、可靠的故障定位是電力設(shè)備狀態(tài)監(jiān)測(cè)急需解決的一個(gè)難題。其主要原因?yàn)殡娏ψ儔浩黧w積龐大、結(jié)構(gòu)復(fù)雜、電磁環(huán)境惡劣，且其絕緣結(jié)構(gòu)中缺陷類型、位置和數(shù)量具有多樣性所致。此外，在PD源定位計(jì)算的過程中，除了背景噪聲、傳感器的響應(yīng)時(shí)間、PD電流脈沖的上升時(shí)間等眾多影響因素導(dǎo)致難以準(zhǔn)確獲取PD信號(hào)時(shí)延之外，以電磁波傳播速度為等值波速建立的時(shí)間差方程組也在一定程度上影響了定位的準(zhǔn)確性，從而出現(xiàn)所謂“誤差多級(jí)放大”的情況，進(jìn)一步降低了PD定位精度，甚至無法定位。同時(shí)，目前的定位算法還面臨著對(duì)時(shí)延誤差敏感、易局部收斂或發(fā)散、運(yùn)算速度慢等難點(diǎn)。 以上的不足，在一定程度上嚴(yán)重制約了基于UHF技術(shù)進(jìn)行變壓器PD源定位的應(yīng)用。為此，針對(duì)到達(dá)時(shí)間差（Time Difference of Arrival, TDOA）定位法中對(duì)時(shí)延精確獲取依賴性較大和因時(shí)延獲取精度不高而帶來定位誤差較大的難題，引入“先粗后細(xì)”的理念，提出逐次逼近定位PD源的方法，以期解決針對(duì)變壓器PD難以準(zhǔn)確、快速定位的難題。本文開展的主要工作和所取得的創(chuàng)新性成果如下： ①提出一種基于“相關(guān)—移位—疊加”方法的四階累積量時(shí)延估計(jì)改進(jìn)算法。對(duì)來自同一放電源的多個(gè)樣本數(shù)據(jù)先進(jìn)行“相關(guān)-移位-疊加”數(shù)學(xué)變換后得到具有統(tǒng)計(jì)意義的PD信號(hào)波形，再利用四階累積量準(zhǔn)確地求取時(shí)間差。該方法不僅能有效消除所獲PD信號(hào)的水平晃動(dòng)和隨機(jī)干擾，還可以有效地抑制高斯噪聲提高信噪比，提高了時(shí)延測(cè)量準(zhǔn)確性。 ②針對(duì)目前TDOA定位PD源存在對(duì)時(shí)延誤差敏感、易局部收斂或發(fā)散以及運(yùn)算速度慢等難點(diǎn)問題，提出一種可用于時(shí)間差定位方程組求解的半定松弛方法。將難以求解的時(shí)間差定位方程組通過等價(jià)變換和秩1松弛轉(zhuǎn)化為一個(gè)半定規(guī)劃問題，使得松弛后的問題易于求解且具有唯一的全局最優(yōu)解。研究結(jié)果表明，半定松弛解法可降低對(duì)時(shí)延誤差的敏感性，有效地對(duì)TDOA定位方程組進(jìn)行求解，并確保得到的結(jié)果是全局最優(yōu)解從而獲得更高的定位精度，且較傳統(tǒng)定位算法具有較高的定位效率。 ③為了降低時(shí)間差定位法中對(duì)準(zhǔn)確獲取時(shí)延的依賴性，提出了一種基于多樣本尋優(yōu)PD源的逐次逼近定位方法，以消除定位誤差過大帶來的PD源難以準(zhǔn)確判斷的問題。實(shí)測(cè)結(jié)果表明，提出的逐次逼近定位方法可有效地解決因時(shí)間差測(cè)量不準(zhǔn)確而引起的定位結(jié)果較差的難題，，誤差滿足變壓器PD定位要在數(shù)米范圍內(nèi)達(dá)到數(shù)厘米的定位精度要求。 ④通過采用半定松弛算法與逐次逼近定位技術(shù)對(duì)多樣本數(shù)據(jù)計(jì)算后，得到的定位精度有了明顯的提高，解決了單樣本因時(shí)間差測(cè)量不準(zhǔn)確而引起的定位結(jié)果分散、誤差較大的問題，誤差由之前單樣本的數(shù)十厘米減少到數(shù)厘米，且高于用平均值法計(jì)算的結(jié)果，確保了PD源定位的準(zhǔn)確性。且定位精度會(huì)隨著每次選擇樣本數(shù)（即m值）的減小而變得越高，不足之處在于計(jì)算量也隨之增大。
[Abstract]:Partial discharge ( PD ) is a kind of discharge phenomenon generated in the local area when the insulation defect occurs in the electrical equipment . The majority of the faults of the power transformer are the PD produced by the internal insulation defects , which can lead to the failure of the whole insulation property of the equipment . In addition , in the process of PD source positioning calculation , besides background noise , response time of sensor and rise time of PD current pulse , it is difficult to accurately obtain PD signal time delay . In addition , besides background noise , response time of sensor and rise time of PD current pulse , it is difficult to accurately obtain PD signal delay . In order to solve the difficult problem of accurate and fast positioning of transformer PD , this paper puts forward a method of successive approximation to locate the PD source in order to solve the difficult problem that the transformer PD is difficult to accurately and quickly locate . The main work and the achievements made in this paper are as follows : This paper proposes an improved algorithm based on " correlation - shift - superposition " method to estimate the fourth - order cumulant delay estimation . After the " correlation - shift - superposition " mathematical transformation is performed on multiple sample data from the same discharge source , the PD signal waveform with statistical significance is obtained , and the fourth - order cumulant is used to accurately calculate the time difference . The method not only can effectively eliminate the horizontal shaking and random interference of the obtained PD signal , but also effectively suppress the Gaussian noise and improve the signal - to - noise ratio , and improve the accuracy of time delay measurement . The results show that the semi - definite relaxation method can reduce the sensitivity of the time delay difference and solve the problem easily and have the only global optimal solution . The results show that the semi - definite relaxation method can reduce the sensitivity of the time delay difference , effectively solve the problem of the time delay difference , and ensure that the obtained result is global optimal solution so as to obtain higher positioning accuracy , and the traditional positioning algorithm has higher positioning efficiency . ( 3 ) In order to reduce the dependence of the time delay on the accurate acquisition time delay , a successive approximation positioning method based on a plurality of optimal PD sources is proposed to eliminate the problem that the PD source is difficult to judge accurately due to the excessive positioning error . The experimental results show that the proposed successive approximation positioning method can effectively solve the problem that the positioning result caused by inaccurate time difference measurement is poor , and the error satisfies the positioning accuracy requirement of the transformer PD to reach several centimeters in the range of several meters . ( 4 ) The accuracy of the positioning accuracy of PD source is solved by using semi - fixed relaxation algorithm and successive approximation positioning technique . The error is reduced from tens of centimeters of the previous single sample to several centimeters , which is higher than the result calculated by means of average method , which ensures the accuracy of PD source positioning .

【學(xué)位授予單位】：重慶大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：TM855

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