基于Labview的GIS局部放电

TheHardwareandSoftwareInterfaceofPortableUHFDetectionSystemforGISPartialDischargeBasedonLabviewPlatformHuiWang,ZhenshengWu,TianjianWangSchoolofElectricalEngineering,BeijingJiaotongUniversityNo.3Shangyuancun,HaidianDistrictofBeijing,P.R.ChinaAbstract:AsforUHFdetectionofpartialdischarge,ahardwareinterfaceisessentialinintroducingtheelectricalsignalofdischargeintocomputerforfurtheranalysisandidentification.Herein,thissystemisdevelopedinLabviewplatformofNICorporationanddataacquisitioncardisconnectedwithcomputerthroughUSBbus.SotheauthorexploredthehardwareinterfaceincludingthedataacquisitioncardandhowtocollectthedatatoLabviewplatforminordertoclassifythetypeofdischargeusingdynamiclinklibrary(DLL)document.Keywords-DLL;GISpartialdischargedetection;high-speeddataacquisitionI.INTRODUCTIONTheGasInsulatedSubstation(GIS)isametalcontainerwherenearlyallhigh-voltageelectrifiedbodies,includingthebreakers,disconnectors,groundingswitches,currenttransformers,voltagetransformers,arresters,high-voltagebusesandcasingpipes,aresealedwithSF-gasinsulatingmedium.Thisdesignmakesithavetheadvantagesofcompactstructure,anti-interference,reliableoperationandwithlongmaintenancecycle.Soithasbeenwidelyusedforpowersystemconstruction.Apparently,thesafeoperationofGISisextremelyimportantsinceanyfaultwillcauseoutageinavastarea,andit’sofsignificantimportancetodetecttheinteralhiddentroublesintime.Theultra-highfrequency(UHF)detectionmethodiswidelyusedforonlinedetectionofGISpartialdischarge.Ithashighsensitivityandissuitableforallthetypesofflaw,moreoveritcandistinguishdefecttypeandpreciselylocatethem.ByusingUHFenvelopedetectioncircuittoextracttheenvelopewaveformoftheGISpartialdischargesignalfromthesensortodataacquisitioncard,itnotonlydecreasesthedemandofsamplingfrequencyanddataquantity,butretainsthedetailsofpartialdischarge.TheLabviewsoftwareplatformfromNIcorporationandHandyscope4(HS4forshort)dataacquisitioncardfromTIEPIEinNetherlandwerechosenforanalyzingandcollectingsignalsrespectively.Inthepaper,aplatformforoperatingbackgroundsoftwareisbuiltinordertoprovideafoundationforfurtherdataanalysisandsmartidentification,andtheDLLfilesprovidedbyTIEPIEisusedtodrivetheHS4card,II.THEINTERFACECONNECTEDTOTHELAPTOPOFONLINEDETECTIONSYSTEMTheUHFdetectionsystemofGISpartialdischargeincludesaultra-highfrequencysensor,highfrequencycables,apeakenvelopedetectioncircuit,ahighspeeddataacquisitioncard,thevoltagetransformcircuitandthelaptop.ItisshowninFigure.1.Figure1.HardwarestructureofGISpartialdischargedetectorA.Ultra-highFrequencySensorTheultra-highfrequencysensorismadeupbyanantenna,band-passfilter,amplifier,couplerandshieldingenclosure.Theplanarequiangularspiralantennaisusedhere.Becausethefrequencyofdisturbingsignalisbelow500MHZandmeanwhilethepartialdischargeisaround1000MHZ,thatoftheband-passfilterisdesignedbetween500MHZand1500MHZ.Sincethesignalofthedischargeisweakandwhat’smoredecreasedwhenitistransmitting,agreatgainamplifierwithhighlimitfrequencyisneeded.B.EnvelopeDetectorUsuallyahigh-performanceoscilloscopewithhighsamplingfrequencyandhugememorycapacitanceisdesperatelyneededsincetheultra-highfrequencysignalsobtainedfromthesensorcontainhugequantitiesofdata.Aimingatdesigningahandyonlinepartialdischargedetectionequipment,aenvelopedetectorisusedheretoprocessthesignals.Comparedtotheoscilloscope,thisstrategyretainsalltheGISpartialdischargedetailsandlowerstherequirementofthesamplingrateanddatacapacity.978-1-4244-6255-1/11/$26.00©2011IEEEFigure2.EnvelopedetectorcircuitTheSMS7630highfrequencydiodeisusedinpreparingtheenvelopedetectorinpracticeanditsequivalenton-resistance(Rd)is2.6kΩwithabiascurrentof10μA.ThevalueofthecapacitorshouldbeaslowaspossiblesoanATC100highfrequencycapacitorof1pFisselected.Onthecontrarya470kΩhigh-frequencyresistorisusedtomaximizeload.Thisconfigurationcanprovideachargetimeconstantthatissmallenoughandadischargetimeconstantlargeenoughasneeded,sotheerrorofenvelopepeakvalueiscontrollableandlimitedinareasonablerangeinpracticaltest.C.High-speedDataAcquisitioncardAccordingtoShannonsamplingtheorem,itisrequiredthatsamplingfrequencyshouldbeatleast2timeshigherthandischargesignalfrequency.However,whentheenvelopecircuitisusedsuchahighsamplingfrequencywon’tbenecessary.Thedataacquisitioncardhasthehighestsamplingfrequencyof50MHz,avoltageinputrangeof0.2V~80V,avariableresolutionfrom12bitto16bitwith4channels,and128KstorageRAMaswellassophisticatedtriggerforeachchannel.HS4supportsmanyprogramminglanguagesincludingC++,Delphi,JavaandLabview.DuetothesuperiorgraphicalfeatureofLabviewprogrammingalongwithitsDLLsupportprovidedbyTiePie,Labviewlanguageisquiteconvenientfordevelopingsoftware.D.VoltageTransformDeviceThevoltagetransformdeviceisadoptedtoadjustandconfinethetargetvoltageintotheinputrangeofHS4cardThewaveformoflocal220Vpowervoltageisusedasacontrol,butitcannotbeinputintotheacquisitioncarddirectly,asaresultaHPTmicrovoltagetransformerwith200:1transformationratioisusedtoisolatetheover-voltageandlowertheinputvoltage.III.THESOFTWAREINTERFACEOFHS4HIGH-SPEEDDATAACQUISITIONCARDANDLABVIEWPLATFOR