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1、南京理工大學(xué)畢業(yè)設(shè)計(jì)說明書(論文)作者:楊加意學(xué)號:1010190210學(xué)院(系):自動化學(xué)院專業(yè):電氣工程及其自動化題目:變壓器勵(lì)磁涌流識別方法研究副教授王寶華指導(dǎo)者:講師張慧麗評閱者:2014年5月畢業(yè)設(shè)計(jì)說明書(論文)中文摘要電力變壓器在空載合閘或外部故障切除后電壓恢復(fù)時(shí),因鐵芯瞬間飽和而產(chǎn)生很大的電流,稱為勵(lì)磁涌流。該電流在可達(dá)到正常勵(lì)磁電流的數(shù)百倍,數(shù)值為正常額定電流的5~8倍。其相應(yīng)的電壓與電流波形也會發(fā)生畸變,存在間斷角,并且產(chǎn)生大量諧波,其中又以二次諧波為主。本文利用MATLAB/Simulink仿真平臺,建立起在變壓器空載合閘
2、時(shí)以及外部故障切除后電壓恢復(fù)時(shí)的勵(lì)磁涌流的仿真模型,再對所產(chǎn)生的勵(lì)磁涌流波形的特點(diǎn)進(jìn)行分析。并采用將數(shù)學(xué)形態(tài)學(xué)與二次小波變換相結(jié)合的識別方法,構(gòu)建出形態(tài)學(xué)梯度算子,識別出對稱性勵(lì)磁涌流;再進(jìn)行二次小波變換,分析是否存在相鄰局部模極大值符號相同,識別出非對稱性勵(lì)磁涌流。仿真結(jié)果表明,該方法可快速有效識別出勵(lì)磁涌流。關(guān)鍵詞勵(lì)磁涌流數(shù)學(xué)形態(tài)學(xué)二次小波變換MATLAB畢業(yè)設(shè)計(jì)說明書(論文)外文摘要TitleTheResearchonIdentificationofTransformersInrushCurrentAbstractBecauseofthe
3、ironcoresaturation,therehasalargecurrentinpowertransformerafterboththeexternalfaultsareremovedandno-loadclosing,itistheinrushcurrent.Thecurrentcanreachhundredstimesofthenormalfieldcurrent,valueforthe5~8timesofthenormalratedcurrent.Itwouldmakethewaveformofelectricvoltageandcu
4、rrenttodistort,andproducethedeadangleandalargenumberofharmonics,whichthesecondharmonicisthemost.ThispaperintroducethatusingMATLAB/Simulinksimulationplatformtoestablishthecorrespondingsimulationmodels,whichisaboutthecurrentinpowertransformerafterboththeexternalfaultsareremove
5、dandno-loadclosing.Thenanalyzingthecharacteristicsofthegeneratedinrushcurrent.Usingtheidentificationmethodwhichiscombinedwiththemathematicalmorphologyandthesecondarywavelettransforms.Thenbuildingoutthemorphologicoperatorandtoidentifythesymmetryexcitationinrushcurrent.Afterth
6、is,throughthesecondarywavelettransforms,observingwhethertherearetheadjacentlocalmodelmaximathathavethesameoperationalsigntoidentifytheasymmetricinrushcurrent.Thesimulationresultsshowthatthismethodcanidentifytheinrushcurrentquicklyandeffectively.Keywordstheinrushcurrentmathem
7、aticalmorphologysecondarywavelettransformsMATLAB本科畢業(yè)設(shè)計(jì)說明書(論文)第I頁共I頁目次1緒論11.1研究課題的背景與意義11.2勵(lì)磁涌流研究現(xiàn)狀11.3本文的主要工作32變壓器勵(lì)磁涌流分析52.1空載合閘勵(lì)磁涌流產(chǎn)生原理52.2外部故障切除后電壓恢復(fù)性勵(lì)磁涌流產(chǎn)生原理72.3本章小結(jié)93勵(lì)磁涌流與故障電流的仿真103.1MATLAB軟件簡介103.2空載合閘勵(lì)磁涌流仿真103.3電壓恢復(fù)性勵(lì)磁涌流仿真153.4內(nèi)部故障電流仿真173.5本章小結(jié)194基于數(shù)學(xué)形態(tài)學(xué)原理的故障電流與勵(lì)磁涌流識別2
8、04.1數(shù)學(xué)形態(tài)學(xué)基本理論204.2數(shù)學(xué)形態(tài)學(xué)區(qū)分勵(lì)磁涌流與故障電流214.3本章小結(jié)285基于二次小波變換與局部模極大值的故障電流與勵(lì)磁涌流識別30