基于LabVIEW的英文文献Word下载.docx
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基于LabVIEW的英文文献Word下载.docx
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sinterfaceandthevisualprogrammingelements.
Keywords:
dataacquisition,graphicalprogramming,Halleffect,electricpower
1Introduction
TheuseoftheLabVIEWgraphicalprogrammingenvironmentensurestheanalysisandstudyofpowermeasurementmethodsinsingle-phaseandthree-phasealternativecurrentcircuits[3,6,7].Theevolutioninbothelectricmeasurementtechnique,intheelectronicfieldandintheareaofdataacquisitionsystems,argumentstheopportunityandjustificationofdesigningnewinstrumentsinordertoimprovetheresearchactivityinthisarea[2,3].
Themodernappliedmetrologyisintegrallylinkedwithotherfast-growingdomains,suchascomputertechnology,dataprocessingandtelecommunications.Adaptationoftheinformationsystems’techniquesfortheneedsofmeasurementsystemscreatedanewinterdisciplinaryfielddealingwithDistributedMeasurement-ControlSystems(DMCS).ElementsofDMCS(nodes)aredistributedterritorially,connectedviawiredorwirelessnetworkandabletoexchangeinformationbetweeneachother.CurrentlytheresearchintheareaofDMCSisfocusedontheapplicabilityissuesandadaptingofnewinformationandcommunicationtechnologiesforsuchsystems[8].Nowadays,averyimportantissueinDMCStechnologyensuresthesafetyofcommunication.Inmanycases,thesuccessofoftencostlyexperimentsormissionsandalsothebiologicalandeconomicalsecuritydependsontheproperfunctioningofsuchsystems.Duetothestillgrowingintegrationwithtelecommunicationsandgeneralpubliccomputernetworks,thesecurityofdistributedmeasurementsystemshasbeendramaticallyreduced.InmanyDMCStheinformationsecurityofthenetworkbecomesoneofthemajordevelopmentproblems.Informationsecurityissuesarealsoveryimportant(becauseofthespecificopennessofsuchsystems,andeaseofattack)inthewirelessandmobileDMCSsystems.SincethenodesofDMCScanbebothsocalledMeasuringServers,usuallybasedonPCswithhugeprocessorpower,aswellasmobilewirelesssensorspoweredfrombattery,theexistingdisparityofcalculationpowermakesanotherimportantissueforthedevelopmentofcommonmethods,ensuringthesafetyofDMCS.Thereforethereisanurgentneedtodeveloppropermethodsandtoolstoensurethesafetyandsecurityofthesesystems[1,8].
Thesoftwareplaysnowadaysahugeroleinmeasurementsystemsandveryoftendeterminestheirquality.Thegrowingprocessors’computingpowerandmemorycapacityallowsforthedevelopmentofmorecomplexsoftware.Animportantissuebecomesthecreationofnewmethodsandsoftwaretoolsfordesigningdistributedmeasurementsystems,andinparticularlow-costandeasyto-uselibrariesandtoolsfordesigningsoftwarethatprovidessecureexchangeofinformationindependentlyofusedinformationandcommunicationinfrastructure.
ExistingsoftwaredesigntoolsdedicatedforDMCS,integratedsoftwareenvironmentssuchasLabVIEW,LabWindows/CVI,HPVEE,enablesimpleandflexibledevelopmentprocessofapplications,butamongothersdonotincludelibrariesforsecuredataexchange.Thesecurityproblemwasonlyslightlyconsideredwhichhasresultedintheintroductionofcertainaccesscontrolmechanismstocertainpartsofanapplication(frontpanelsandtheircomponents)basedonloginandpasswordidentificationsystem.Butthereisnouseofcryptographicmethods,andtheinformationbetweennodesissentexplicitly,mostlyasaplaintext.
Therefore,itseemsnecessarytodevelopacompletelibraryoffunctions,programsandtoolstailoredtospecificprogrammingenvironments,whichwouldgivetheapplicationorsystemdevelopertheopportunitytodesignandsimulatesecureandsafedistributedmeasurementsysteminaneasyandintuitiveway.Theseadditivesshouldhelptoensuresafetransmissionofdatainanycommunicationinfrastructureandthecreationofmechanismsforauthenticationandintegrityofbothmeasurementandcontroldata.
Inthepreviouswork,theauthorshaveanalyzedtheLabVIEWenvironmentcapabilitiesforefficientimplementationofcryptographicalgorithms[1].Thenextphaseofthework,describedinthispaper,istodevelopnewmathematicaltoolforLabVIEWenvironment-aLargeNumberlibrary(alsoknownasBigIntegerorarbitrarylengthintegerlibrary).Thislibraryallowsforthecomputationonnumberswitharbitrary(withinthelimitsofavailablememory)numberofdecimaldigits,farexceedingthetypicalrepresentationincomputersystems(32or64bit).Largenumbersarewidelyusedinmanypopularcryptographicalgorithms,includingRSA,RabinorElGamalpublic-keyencryptionsystems,usedforboth,dataencryptionandthegenerationofsecuredigitalsignatures[2,3].TheLNlibraryinadditiontobasicarithmeticoperationincludesoperationmoduloNinthesuitableringsorfinitebodies,functionsforcalculatingtheoppositeelementinsuchalgebrasandprimalitytestalgorithms.
2.PowerMeasurementinSingle-PhaseACCircuits
Theinstantaneouspower[1,2,3,4]toanelectricdipoleisdefinedastheproductoftheinstantaneousvaluesofthevoltage(u)totheterminalofthedipoleandthecurrent(i)thatflowsthroughthedipole:
P=ui
(1)
Theinstantaneouspowercanbeclassifiedintoinputandoutputpower,dependingontheassociationofthevoltage(u)andthecurrent(i),whichrespectstheruleofreceiversandgenerators.Inasine-wavesteady-statewiththeTperiod,theactivepower(P)canbedefinedastheaveragevalueoftheinstantaneouspower,consideringanaturalnumberofperiods:
Forasingle-phasecircuitwhichfunctionsunderasine-wavepermanentrate,inwhichthevoltageandcurrenthavethefollowingexpressions:
itresults:
-theactivepower:
P=UIcosϕ
-thereactivepower:
Q=UIsinϕ(5)
-theapparentpower:
S=UI
Thecomplexapparentpower(S)isdefinedintothesimplifiedcomplexrepresentationastheproductbetweenthecomplexvoltage(U)andtheconjugatecomplexcurrent(I*):
Therealpartofthecomplexpower(S)istheactivepower(P),theimaginarypartisthereactivepower(Q),themoduleistheapparentpower(S)andtheargumentisequaltothephasedisplacement(ϕ)ofthecircuit:
Forasingle-phasecircuitwhichdoesnotfunctioninsine-waverate[4]andhastheterminalvoltageu(t):
therecanbedefined:
theactivepower:
thereactivepower:
theapparentpower:
S=UI(11)
Bytakingintoaccounttherelationsabove,wecannoticethatS²
≠P²
+Q²
andthereforethenotionofdeformingpowercanbeintroduced:
Theapplicationbelow(fig.1)whichisrealizedbyusingtheLabVIEWgraphicalprogrammingenvironment,basingonthepresentedtheoreticalconsiderations[2,5,6,7],allowsthegraphicaldisplayofthetimevariationofthevoltage,thecurrent,theinstantaneousandactivepower.Controlelementsareusedinordertomodifythevoltageandthechargeimpedanceparameters,andalsootherelementsareusedforindicatingthevoltage,thecurrent,thepowerfactor,theactive,reactiveandapparentpower(inordertoobtainanaccurateviewofthecurrent,itispossibletomultiplytheamplitude1,10,20,50or100times).
Fig.1.Single-PhaseACCircuitsOperationandPowerMeasurement–simulation
2.2SignalConditioning
Theacquisitiondataboardisacomplexsystemwhichallowsparametermeasurementandmonitoringfromatechnologicalprocess,usingtransducerswhichcantransformstudiedphysicalmeasuresintoelectricalvoltage[1,3,4,6,7].Forsingle-phaseaccircuits,itisnecessarytoobtainsignalswithvoltage-rangeamplitude,tobeappliedattheinputoftheboard.Forphase/linevoltages,resistivevoltagedividers(donotensuregalvanicisolation)orvoltagemeasurementtransformers(ensuregalvanicseparation)canbeused.Shunts(current-voltageconverter)orcurrentmeasurementtransformerscanbeusedforcurrents.Theuseofbothvoltagedividersandshuntsmustbedonebytakingintoaccountthecurrentthroughthevoltagedivider,thevoltagedropontheshunt,thepowerdissipation,parasiteresistances,self-heatingeffects,dynamiceffects.
Fig.2.Dataacquisitionsystem
Fig.3.Experimentalresults
Theuseofvoltage-currentmeasurementtransformersensurestheenergeticsystem’sgalvanicisolationofthemeasuringsystem,butitintroducesratioandangleerrorsandrealizesaninadequateperturbationtransfer.TheadoptedsolutionwastousecurrentandvoltagetransducersbasedontheHalleffect.Theblockdiagramoftheacquisitionsystemispresentedinfig.2andfig.3presentstheexperimentalresults.
Remark:
Thevoltagevaluesandtheparametersoftheconsumersinfig.3a,wereintroducedintotheapplicationrealizedforsimulation(fig.1).
3.PowerMeasurementinThree-PhaseACCircuits
Forarandom
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