變壓器差動(dòng)保護(hù)的研究畢業(yè)論文

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1、畢業(yè)論文變壓器差動(dòng)保護(hù)的研究[摘要]電力變壓器作為聯(lián)系不同電壓等級(jí)網(wǎng)絡(luò)的設(shè)備，是電力系統(tǒng)中非常重要的元件。長(zhǎng)期以來電力變壓器一直只采用差動(dòng)保護(hù)作為內(nèi)部故障的主保護(hù)。因此，差動(dòng)保護(hù)的可靠性和安全性對(duì)變壓器保護(hù)來說最為關(guān)鍵。其中勵(lì)磁涌流的識(shí)別一直是研究的熱點(diǎn)，國(guó)內(nèi)外許多研究人員做了大量工作，也取得了許多成果。由于變壓器勵(lì)磁涌流受變壓器鐵心剩磁、飽和磁密、系統(tǒng)阻抗、接線方式、鐵心結(jié)構(gòu)、合閘初相角等因素影響，所以這些方法都不能保證百分之百的可靠性，鑒別勵(lì)磁涌流的問題成為制約變壓器差動(dòng)保護(hù)能否正確和靈敏動(dòng)作的瓶頸。本文

2、研究了變壓器產(chǎn)生勵(lì)磁涌流的機(jī)理，分析了幾種鑒別勵(lì)磁涌流方法的優(yōu)缺點(diǎn)。針對(duì)二次諧波制動(dòng)原理存在著不著之處，提出了基于等效瞬時(shí)電感鑒別勵(lì)磁涌流的方法并用MATLAB/SIMULINK建立了仿真模型，對(duì)變壓器在不同合閘角、不同剩磁的情況下進(jìn)行了大量仿真。仿真結(jié)果表明基于等效瞬時(shí)電感鑒別勵(lì)磁涌流的方法能夠有效鑒別變壓器的內(nèi)部故障和勵(lì)磁涌流，具有一定的實(shí)用價(jià)值。[關(guān)鍵詞]變壓器差動(dòng)保護(hù)MATLAB/SIMULINK勵(lì)磁涌流等效瞬時(shí)電感仿真Expioitationtransformerdifferentialprotec

3、tionLiXin(Grade06Class3,MajorElectricengineering，ElectricengineeringandautomationDept.，ShaanxiUniversityofTechnology，Hanzhong723003，Shaanxi)Tutor：YangLinxiaAbstract：Powertransformersasveryimportantelementsinpowersystemrequireveryreliableprotectionhasbeenado

4、ptedasmainprotectionagainstinnerfaultoftransformerforalongtime,sinceithashighreliabilityandhighsensitivity,whicharemostimportantfortransformerprotection.Identificationofinrushcurrenthasbeenakeyproblemtoberesolved.Manyresearchereshavedonealotofworkonthisaspe

5、ct.Becausetheinrushcurrentoftransformerisinfluencedbymanyfactorssuchasresidualfluxofironcore,saturationfluxdensity,systemimpedance,modeofconnection,ironcorestructure,closingangleandsoon,butalloftheproposedmethodscan’tmakesure100%reliability,Identificationof

6、inrushcurrentisthemostcriticalfactorthatlimitsdifferentialprotectionoperation.Inthisthesis,themechanismofinrushcurrentoccurringintransformeriswellresearched,theadvantagesanddisadvantagesofseveralmethodsforcheckinginrushcurrentarediscussed.Basedonequivalenti

7、nstantaneousinductancetodiscriminatebetweeninternalfaultcurrentandinrushcurrentisputforwardinthisthesis.AnumericsimulationmodelisbuiltwiththesimulationsoftwareSIMULIINKbasedonMATLAB,numeroussimulationsarecarriedoutonanconnectedtransformerwithdifferentswitch

8、ing-onangleandremanentflux.Thesimulationresultsshowthattheproposedmethodbasedonequivalentinstantaneousinductancepossessescertainpracticabilityandcandistinguishinternalfaultcurrentfrominrushcurrenteffec