中英文文献翻译-测量单相电能质量参数的数字表的设计和样机研制

DesignandPrototypeDevelopmentofADigitalInstrumentforMeasuringSinglePhasePowerQualityParametersSriramKarakanaElectricalandElectronicsEngineeringGVPCollegeofEngineering(A)Visakhapatnam,AP,Indiaksriram204gmail.comAbstractInpresentpowersystem,themeasurementofpowerqualityisbecomingnecessaryduetothepresenceofnonlinearanddynamicloads.Thispaperproposesadigitalinstrument,designedandplementedashardwaretomeasurebasicsinglephasepowerqualityparameterslikevoltage,urrent,frequency,phaseangle,powerfactor,powerandtotalharmonicdistortion(THD).Theverypurposeofdesigningthishardwarecircuitistohaveknowledgeofmeasuringtheaboveelectricpowerqualityparametersandtoimprovethesystemperformance.ThebasicinputsforthisinstrumentarevoltageandcurrentsignalswhicharesensedbyaHallEffectvoltageandcurrenttransducers.Amicrocontrollerdevelopmentboard(MixedSignalProcessor)MSP430LaunchpadmanufacturedbyTexasInstrumentsisusedfordigitalprocessingofthetwosignals.AllsoftwarerelatedprogrammingiswritteninC-languagecodeinMSP430.A16x2LCDdisplayisusedfordisplayingthepowerqualityparameters.TheimplementedhardwarecircuitistestedwithstandardmetersinthelaboratoryandwithpowerqualitymeterCW240(Clamponmeter)manufacturedbyYOKOGAWAandtheresultoftheexperimentalworkdoneonaprototypeofapowerqualitymeasurementinstrumentisreported.IndexTermsPowerquality,TotalHarmonicDistortion,HallEffecttransducers,MSP430,CW240clamponmeter.NageswaraRaoNamburiProfessor,ElectricalandElectronicsEngineeringGVPCollegeofEngineering(A)Visakhapatnam,AP,Indianageswara.namburigvpce.ac.inI.INTRODUCTIONInpresentpowersystem,thegeneratingsourceswhicharecommonlyfeedingpowerintoelectricgridareroducingdisturbances.Mainlyrenewableenergysourceswhichcontainpowerelectronicconvertersareinjectingharmonicsasdisturbancesintoelectricgrid.Sothereisanecessityofmeasuringpowerqualityofasystembeforeitused.Thereisalsoanimpellingneedtomeasurepowerqualityparameterstoknowtheelectricalsystembehaviorwhichhelpsintakingmeasurestoimproveoverallsystemperformance.Thispaperroposesadigitalinstrumentdevelopedasprototypehardwareforasinglephasepowersystemtomeasurebasicpowerqualityparameterslikevoltage,current,frequency,phaseangle,powerfactor,powerandtotalharmonicdistortion(THD).Sincethemeterisdesignedforasinglephasepowersystem,asinglesetofcurrentandvoltagetransducersissufficient.Tomeasurevoltage,LV-25PHallEffectvoltagetransducerhavingarangeof0-500VmanufacturedbyLEMisused.Foreasuringcurrent,LA-100PHallEffectcurrenttransducerhavingarangeof0-100Aisused.BiasvoltagefortransducersisprovidedbyVoltageregulatorsLM7812andLM7912givingaregulatedpowersupplyof+12Vand-12Vrespectively.AMixedSignalProcessor(MSP430)LaunchpadmanufacturedfromTIisusedfordigitalprocessing.Algorithmsforharmonicanalysis,calculationofrootmeansquarevalues(RMS)functionsandremainingallsoftwarerelatedprogrammingarewritteninC-languagecodeinMSP430.Zerocrossingdetectorstomeasurefrequency,voltagefollowers(buffers)tostrengthensignal,inversioncircuittoinvertnegativehalfcycleintopositiveforADCSamplingaredevelopedbyusingasimpleoperationalamplifier(OP-AMP)circuitry.LM324,aquadchannelOP-AMPisusedforthisI.purpose.A16x2LCDdisplayisusedfordisplayingthepowerqualityparameters.Theimplementedhardwarecircuitistestedwithstandardmetersinthelaboratorylikeammeter,voltmeter,wattmeter,powerfactormeterandalsowiththepowerqualitymeterCW240(Clamponmeter)anufacturedbyYOKOGAWA.Thedevelopedprototypeinstrumentistestedthoroughlyinthelaboratoryandtheresultsarereportedaswellasobservationsarediscussed.II.HARDWARECONFIGURATIONTheblockdiagramoftheproposeddigitalinstrumentisshowninFig.1.ASinglephasepowersystemisindicatedinfigurebyLine(L)andNeutral(N).Theblockdiagrammainlyconsistsoffourparts.TheyareA)HallEffecttransducers.B)Signalconditioningcircuit.C)Digitalprocessingunit-MSP430Launchpad.D)16x2LCDDisplay.A.HallEffectTransducersTomeasureallkindsofpowerqualityparameters,thebasicinputsrequiredarevoltageandcurrent.Soinordertomeasurevoltageandcurrent,aHallEffectcurrentandvoltageTransducers(transducers)manufacturedbyLEMareusedinthisprototype.Thesetransducersaretestedandcalibratedwiththelaboratoryequipment.TheaboveFig.2indicatesvoltagetransducerwhichconsistsoftwoinputterminals(+HTand-HT),threeoutputterminals(+,-,M)andtworesistanceseachatinput(R1)andoutput(Rm).Inputterminals(+HTand-HT)areconnectedtolineandneutralofasinglephasesupplyrespectively.Outputterminals(+and-)areusedtogivepowertothetransducer.Theycanbeconnectedeitherto±12Vor±15V.Remainingoutputterminal(M)isconnectedtogroundthrougharesistanceRmandthevoltagedropacrossRmwillgivestheattenuatedvoltageofinputfromthetransducer.Calculationsforresistancesareasfollows.Primarynominalcurrent(IPN)=10mA.MaxVoltagethatcanbesensedbytransducer=500volts.Inputresistance(R1)=50kiloohms50k,5W.Secondarynominalcurrent(ISN)=25mA.Definedsecondaryvoltageoutput=0.5V.Outputresistance(Rm)=0.5V/25mA=20ohms20,0.25W.Fig.3.indicatescurrenttransducerwhichconsistsofthreeoutputterminals(+,-,M)andaresistanceatoutput(Rm).Itconsistsofahollowstructureinwhichsupplywireiswounded.Outputterminals(+and-)areusedtopowertransducer.Theycanbeconnectedeitherto±12Vor±15V.Remainingoutputterminal(M)isconnectedtogroundthrougharesistanceRmandthevoltagedropacrossRmwillgivestheattenuatedvoltagewhichisanalogoustocurrentmeasurement.Acalculationforresistanceisasfollows.Secondarynominalcurrent(ISN)=100mA.Definedsecondaryvoltageoutput=2V.Outputresistance(Rm)=2V/100mA=20ohms20,0.25W.B.SignalConditioningCircuitIngeneral,ifananalogsignalisintendedtogivetoadigitalprocessorlikeanADCoramicrocontroller,beforegivingitshouldbemanipulatedtomeettherequirementsofnextstageforfurtherprocessing.Thisiscalledassignalconditioning.Operationalamplifiers(OP-AMPS)arecommonlyemployedforthispurpose.Intheproposedprototype,threecircuitsarebuiltusingOPAMPcircuitry.Theyare1)ZeroCrossingDetector.2)Voltagefollower(Buffer).3)Invertingamplifier.1)ZeroCrossingDetectors:Thiscircuitisbuiltformeasuringfrequencyofawaveformwiththehelpofzerocrossingsshowninfig.4.Twoconsecutivezerocrossingsareidentifiedandtimeperiodbetweenthemgivestimeforahalfcyclewhichisusedtocalculatethefrequency.2)VoltageFollower(Buffer):ThiscircuitisusedforamplificationofanalogsignaltomeettherequirementsofADCandpreventsthesecondcircuitfromloadingthefirstcircuit.Becauseanidealoperationalamplifierhasinfiniteinputimpedanceandzerooutputimpedance.Ifgain(Av)ismadeas1,thenitiscalledasunitygainbufferoravoltagefollowerwhichisshowninfig.5.3)InvertingAmplifier:Itisusedforbothamplificationandinversionoftheanalogsignal.InproposedprototypetheADCiscapableofsamplingpositivehalfcycleonly.Soinordertoachievecompletesignalsampling,thenegativehalfcycleisinvertedintopositivewiththehelpofthisop-ampcircuit.Fig.6illustratesitsoperation.C.DigitalProcessingUnitDigitalprocessingUnitisaonewhichprocessesthedigitalsignalstoachieverequiredparameters.Inthisproposedprototype,MSP430F5529Launchpadisusedasadigitalprocessingunit.ThebasicfeaturesarelistedinFig.7.Itconsistsof16channels,12-bitsuccessiveapproximationtypeanalogtodigitalconverter(ADC)inwhichtwochannelsareusedforsamplingpositiveandnegativewaveformsindividually.D.16X2LCDDisplayInordertodisplaythemeasuredquantities,a16x2LCDdisplayisusedinthisprototype.VDDandVSSterminalsareusedtopowerdisplay.VEEterminalisusedforadjustingthecontrastofbackgreenlightinthedisplay.D1toD3bitsaregroundedandD4toD7bitsareusedasdatabitsfordisplay.RS,R/W,Earethecontrolpinstocontrolthedatai.e.toreadorwritefrommeasurementtodisplay.III.MEASUREMENTALGORITHMApartfromhardwarecircuitry,thereshouldbeasoftwaresupportasapartofcodinginordertomeasurepowerqualityparameters.Thiscodinghelpsinconnectingthehardwarecircuitstodigitalprocessorfordeliveringmeasuredparameters.Sointhissectioneveryparametermeasurementalgorithmisdiscussedwhichenablestoknowsoftwareprogramminginthemicrocontroller.Thealgorithmsfordifferentmeasuredquantitiesareasfollows.1)VoltageandCurrent-RootMeanSquareValueMeasurement:AHallEffectVoltageTransducerhavingarangeof0-500VisusedtomeasurevoltageandaHallEffectcurrentTransducerhavingarangeof0-100Aisusedtomeasurecurrentinthisprototype.ThefunctiontofindRootMeanSquare(RMS)Valueisgiveninequation(1)ThefunctionYmaybeavoltageorcurrentwhoseRMSvalueistobefoundandxwillbethenumberofsamplesoveraperiodofonecyclespecificallytakenas128samples/cycle.ThealgorithmformeasuringRMSvalueisgiveninFig.9.2)ActivePower:SoftwarealgorithmiswritteninMSP430takingtheoutputsofvoltageandcurrentsensorsthroughADC.ThefunctiontofindRootMeanSquare(RMS)Valueforpowerisgiveninequation(2).Theobjectiveofthealgorithmistocalculatethevaluesofpowerbymultiplyingvoltageandcurrentateachandeverysampleofthecyclewhichisillustratedinfig.10.Thiswillgivetheactivepowermeasurement.3)Frequency,PhaseAngleandPowerFactor:Frequencyofthesupplywaveformcanbedeterminedbyreciprocalofthetimeperiodbetweenzerocrossingsandthefunctiontofindfrequencyisgivenineqation(3).Frequency(F)=1/Timeperiod(T)-(3)Phaseanglecanbefoundfromzerocrossingsofthevoltageandcurrentwaveformsatsameinstantoftime.Thedifferencebetweenthezerocrossingswillgivesthephaseangleintermsoftimeanditcanbeconvertedintophaseanglebyequation(4).Phaseangle(PA)=TimeDifference*360/TimePeriod-(4).Powerfactorcanbedeterminedbytakingthecosineoftheanglebetweenvoltageandcurrent.i.e.phaseangle.Theexpressionforphaseangleisgiveninequation(5)PowerFactor(P.F)=Cos(phaseangle)(5)TherelatedsoftwarealgorithmforfindingthesethreeparametersisshowninFig.11.Italsoconsistsofaseparatealgorithmtodenoteleadingaswellaslaggingpowerfactors.4)Harmonics(TotalHarmonicDistortion):Harmonicsarethefrequenciesotherthanthefundamentalfrequency.Usuallytheyaremultiplesoffundamentalfrequency.Theycausedisturbancesinthepowersupplywhichwillproduceheat,noise.,etc.andalsoleadtonon-sinusoidalwaveformswhichmaydamagetheelectricalequipment.Tofindoutthem,amathematicalapproachFastFourierTransform(FFT)Analysisisusedwhichwillgivestheindividualharmonicsaswellastotalharmonicdistortion(THD).ThecalculationofharmoniccomponentsinananalogvoltageorcurrentwaveformisillustratedinFig.12.Initially,thesignalfromthevoltageorcurrenttransduceroutputisgiventoanADCinwhichitsampledas128samplespercycleandthatsampleddataisusedinprocessingofFFTanalysistocalculateHarmonics.ThemainpurposeofFFTanalysisistoconverttimedomainsignalintofrequencydomainwhichisexpressedbyequation(6).WhereK=0,1,2,.N-1Wherenistimedomainordinalandkisfrequencydomainordinal.NumberofsamplesisrepresentedbyNwhichis128inthiscase.Afterconvertingintofrequencydomain,wewillgettheexpressionas.thenthemagnitudeandphaseoftheharmonicscanbefoundbyequation(7).Duringtheconversionoftimedomainsignalintofrequencydomain,itisinterestingtoknowthatevensamplesandoddsamplesareseparatelyprocessedandfinallycombinedasshowninFig.13.ThesoftwarealgorithmtoforFFTanalysisisimplementedasshowninFig.14.Initiallydataisgiveninbitreversalorderasshowninfig.13andthenprocessedforfirststage,inthatfirstgroupandfirstbutterfly.Aftercomputationofthatbutterfly,thenitwillcompletesremainingallotherbutterfliessituatedindifferentgroupsofdifferentstagesasperabovealgorithmandfinallygivesthevaluesofHarmonicsinfrequencydomain.Inthisproposedprototype,itiscapableofmeasuring1to63orderharmonicsalongwithtotalharmonicdistortion(THD).Thetotalharmonicdistortionisdefinedastheratioofthesumofthepowersofallarmoniccomponentstothepowerofthefundamentalfrequencyasgiveninequation(8).Itdenotesthecompleteharmonicdistortionpresentinthesignal.Regardingmeasurement,specificallythepercentageTHDofthevoltagewaveformonlyispresentedintheLCDdisplay.IV.PROTOTYPEDEVELOPMENTANDTESTINGTheabovediscussioninthesectionsIIandIIIdescribesaboutthehardwareandsoftwareprogrammingthathavebeenusedinthisprototype.Inthissection,theentireschematicoftheproposedworkwhichshowstheconnectionofallcomponentsasinFig.15anditsdescriptionarediscussedindetail.Infig.15,itisobservedthatasinglephasepowersupplyisconnectedthroughvoltageandcurrenttransducerstoaloadwhosepowerqualityparametersaretobefound.Loadmaybearesistive,inductive,capacitiveorcombinationsofany.Regulatedpowersupplyisprovidedinordertogenerate+12V,-12Vforbiasingtransducersand+5VforpoweringMSP430microcontroller,LCDdisplay.AsalreadydiscussedinsectionII,op-ampcircuitryisusedforthreepurposesnamelyzerocrossingdetection,signalstrengtheningandsignalinversion.ThesethreecircuitsarebuiltforbothvoltageandcurrentusingaQuadchannelLM324OP-AMP.TheinputsforallthesethreecircuitryaresamenamelyVmandImwhicharenothingbutoutputsofvoltageandcurrentsensors.Theoutputsofthenoninvertingbufferforvoltageandcurrentaregiventoport6.0and6.2,outputoftheinvertingbuffersaregiventoport6.1and6.3andoutputofthezerocrossingdetectorsaregiventoport1.0and2.2respectivelyReferringtothesectionIII,thedigitalprocessingisexplainedandafteritscompletion,themeasuredelectricalparametersaredisplayedontheLCDbyconnectingthedatabitsD4,D5,D6andD7totheports3.4to3.7.Measuredparameterswillrepeatforeverycyclecontinuously.Testingoftherealizedprototypewasconductedinthelaboratorywithavailablestandardinstrumentslikeammeter,voltmeter,wattmeter,powerfactormeteralongwithdigitalstorageoscilloscope(DSO)andpowerqualityanalyzer(CW240)anufacturedbyYokogawacompany.Fig.16representstheprototypewithexperimentalsetupinthelaboratoryfortestingitsresponse.Duringexperimentation,prototypeistestedwithdifferentloadslikeR,RL,RC,andRLC.Italsotestedwithanonlinearloadtakenasinverteroutput.ThefinalresultsandobservationswillbediscussedinsectionV.Forexperimentation,thevalueofloadsRistakenas100ohms,Las50mHandCas50uF.SpecificationsofProposedPrototype:V.RESULTSANDOBSERVATIONSReferringtosectionIV,thetestingonprototypewithdifferentloadsarecarriedoutandtheresultsareasfollows.Observations:a)Theprototyperesultsarecomparedwithstandardinstrumentsresultsandnoticedthat,itishavingfairaccuracyexceptincaseofpercentagetotalharmonicdistortion(THD)ofvoltage.SothecodewrittenforFFTanalysisisvalidatedwiththeMATLABandtheresultsofindividualharmonicsalongwithTHDfoundtobeexactlysame.Sotheerrorismerelyduetothenoiseatthesensoroutputwhichwasobservedinthedigitalstorageoscilloscope.b)Sincethesoftwareiswrittenconsideringzerocrossingdetectionofvoltageandcurrentwaves,thisprototypemeterisgivingerrorsinthemeasurementsforaPWMWaveform(whichhasmanyzerocrossingsinacycle).VI.CONCLUSIONTheproposedprototypeisdesignedandimplementedtomeasurebasicpowerqualityparametersinasinglephasepowersystemwithfairaccuracy.Thisprototypehasbeendevelopedsatisfactorilywiththelimitedinputsanditcanbemadeintoalowcostproductbyprovidingupgradedenvironmentinthebothsoftwareandhardwaresections.Itmakesthesenseofknowingelectricalsystembehavioragainststandardsandfurtherleadstotakemeasurestoimprovethesystemperformance.Itisabasicstepforadvancedsmartmetering.ByprovidingnoiseimmunecircuitsatsensoroutputandchoosingmodernlatestcontrollerslikeDSPorFPGA,itcanbemerelyagoodequipmenttoanalyzealltypesofpowerqualityissues.ThisprototypeisalsocapableofmeasuringpowerqualityparametersforaPulsewidthmodulated(PWM)waveformsbyreplacingzerocrossingdetectionschemewithPhaseLockedLoop(PLL)synchronization.Thisworkcanbefurtherextendedtomeasurethreephasequantitiesbyprovidingadditionalequipment.REFERENCES:1AlessandroFerrero,MassimoLazzaroni,andSimonaSalicone“ACalibrationProcedureforaDigitalInstrumentforElectricPowerQualityMeasurement”IEEETransactionsonInstrumentationandMeasurement,Vol.51,No.4,August2002.2LoredanaCristaldi,AlessandroFerrero“AMethodandRelatedDigitalInstrumentfortheMeasurementoftheElectricPowerQuality”IEEETransactionsonPowerDelivery,Vol.10,No.3,July1995.3TomasRadil,PedroM.Ramos,A.CruzSerra“single-phasepowerqualityanalyzerbasedonanewdetectionandclassificationalgorithm”XIXIMEKOWorldCongress,FundamentalandAppliedMetrology,September611,2009,Lisbon,Portugal.4I.Iljazi,L.Arsov,M.Cundeva-BlajerandA.Abazi“CalibrationofaVirtualInstrumentforPowerQualityMonitoring”InternationalConferenceonRenewableEnergiesandPowerQuality(ICREPQ12)SantiagodeCompostela(Spain),28thto30thMarch,2012.测量单相电能质量参数的数字表的设计和样机研制SriramKarakanaElectricalandElectronicsEngineeringGVPCollegeofEngineering(A)Visakhapatnam,AP,Indiaksriram204gmail.comNageswaraRaoNamburiProfessor,ElectricalandElectronicsEngineeringGVPCollegeofEngineering(A)Visakhapatnam,AP,Indianageswara.namburigvpce.ac.in摘要:在电力系统中，由于非线性和变化负载的存在，对电能质量的测量变得越来越重要。本文提出了一种数字仪表，设计并实现硬件测量基本的单相电能质量参数如电压、电流、频率、相位、功率因数、功率和总谐波失真（THD）。本硬件电路设计的目的是对上述电能质量参数进行测量，提高系统的性能。该仪器的基本输入为电压和电流信号，由电压和电流霍尔传感器检测。微控制器开发板（MSP430混合信号处理器）发射台由德克萨斯仪器制造用于两信号的数字处理。所有软件相关程序是用C语言代码在MSP430内部编写。一个16x2字节的液晶显示器用于显示电能质量参数。硬件电路的测试是用标准仪表在实验室完成的。通过使用YOKOGAWA生产的钳式电能质量计cw240，电能质量参数测量设备的实验结果会被报告出来。关键字：电能质量；总谐波畸变；霍尔传感器；MSP430；cw240I.引言在现代电力系统中，输入到电网中的电能的扰动主要是连续电源中的电力电子变换器注入到电网的谐波造成的。因此，在使用前有必要对一个系统的电能质量参数进行测量。并且为了能够更好的提高系统的整体性能，需要对其电能质量参数进行测量。本文提出了一种数字仪表，设计并实现硬件测量基本的单相电能质量参数如电压、电流、频率、相位、功率因数、功率和总谐波失真（THD）。由于该仪表是专为一个单相电力系统设计的，因此一套电流和电压传感器是满足设计需求的。对于电压，lv-25p霍尔电压传感器可以满足0-500V的变化范围。对于电流的测量，la-100p霍尔电流传感器可以满足0-100A的测量范围。传感器的偏置电压+12V和-12V分别是由稳压器LM7812和LM7912给稳压电源提供。混合信号处理器（MSP430）发射台采用TI用于数字处理。算法方面采用计算均方根值（RMS）功能来分析谐波，并且相关程序由C语言编写到MSP430中。硬件方面采用一个简单的运放电路过零检测电路来测量频率，并以电压跟随器来加强信号的强度，通过整流电路将最后的信号传递给ADC采样。其中LM324为四通道运算放大器，用于整流和过零检测电路。1602液晶显示器用于显示电能质量参数。硬件电路与实验室中的标准表如电流表、电压表、功率表，功率因数表和电能质量流量计进行比对测试。所有的硬件都在实验环境中进行了测试并将测量数据进行记录和分析。II.硬件组成该数字仪器框图如图1所示。单相电力系统由线路（L）和中性（N）。方框图主要由四部分组成。他们是a)霍尔效应传感器。b)信号调理电路。c）数字处理unit-msp430发射台。d）1602液晶显示器。A霍尔效应传感器要测量各种电能质量参数，所需的基本输入是电压和电流。因此，为了测量电压和电流，霍尔电流电压传感器（换能器）制造的问题进行原型。这些传感器进行测试和校准与实验室设备。上面的图显示电压互感器由两个输入端（+HT，HT），三个输出端（+，-，M）和两个电阻（R1）每个输入和输出（RM）。输入端子（+HT，HT）连接线和一个单相电源为中性。输出端（+和-）被用来给换能器的功率。他们可以连接到±12V或±15V。剩余的输出端（M）通过一个电阻RM和接地在RM的电压降会从换能器输入衰减电压。电阻的计算如下。初级额定电流（IPN）=10mA。最大电压，可以通过传感器感应=500伏。输入电阻（R1）=50公斤50K欧姆，5W。次级额定电流（是）=25。定义的次级电压输出=0.5V输出电阻（RM）=0.5v/25ma=20ohms20,0.25w。图3。显示电流传感器由三个输出端子（+，-，M）和输出电阻（RM）。它由一个中空的结构，在该结构中，供电线为裸线。输出端子（+和-）是用于功率传感器。他们可以连接到±12V或±15V。剩余的输出端（M）通过一个电阻RM在RM的电压降会连接到地面的衰减电压与电流测量。电阻的计算如下。次级额定电流（是）=100mA。定义的次级输出电压为2V。输出电阻（RM）=2V/100mA=20ohms。B信号处理电路一般来说，如果一个模拟信号的目的是给一个数字处理器像ADC或微控制器，然后给它应该操纵以满足要求的下一阶段进一步处理。这被称为信号处理。运算放大器是常用的信号处理电路。该模块中，三种电路由运放电路建立。他们是：1）过零检测器。2）电压跟随器（缓冲区）。3）反相放大器。1）过零检测电路：该电路通过零检测电路来实现信号频率的测量。如图4所示。两个连续的过零点和他们之间的时间为信号周期的一半，用来计算信号的频率。2）电压跟随器（缓冲区）：该电路是用来满足ADC的要求模拟信号放大和防止第二电路加载第一个电路。由于一个理想的运算放大器具有无限的输入阻抗和输出阻抗。如果增益（AV）为1，则称为单位增益缓冲器或电压跟随器，如图所示。3）反相放大器：它是用于模拟信号的放大和反相。在电路中ADC只能输入正极性信号，因此，为了实现完整的信号采样，在该运算放大器电路的帮助下，负的半周期的信号反向变为正的。如图：C数字处理单元数字处理单元用来处理数字信号，实现所需的参数要求。本文提出的原型，MSP430F5529发射台作为数字处理单元。其基本特征是如图7所示。它由16个通道的12位逐次逼近型模拟数字转换器（ADC）在这两个通道非别对正极和负极信号单独进行采样。D1602LCD液晶显示器在该模块中，1602液晶显示器用来显示被测量。VDD和VSS端子用于功率显示。V终端用于显示调整后的绿色光的对比。D1D3和D4位接D7位用于显示数据位。遥感，R/W，E是控制引脚来控制数据，即从测量到读或写显示.III.测量算法除了硬件电路，应该有一个软件支持作为编码的一部分，以测量电能质量参数。这种编码有助于连接硬件电路的数字处理器提供测量参数。因此，在这一部分中，每个参数的测量算法进行了讨论，使知道在微控制器的软件编程。不同测量量的算法如下。1）电压和电流均方根值测量：霍尔电压传感器具有一系列0-500V是用来测量电压和霍尔电流传感器具有一系列0-100a是用来测量电流这一原型。在方程（1）中给出了根均方值（有效值）值的函数该函数Y可能是一个电压或电流，其有效值是被发现和X将是一个周期的样本数超过一个周期，特别是作为128个样品/周期。测量有效值的算法在图9中给出。2）有功功率：软件算法是用MSP430以电压和电流传感器的输出通过ADC。函数来找到根均方（有效值）值的公式（2）。该算法的目的是计算功率值乘以电压和电流在每个周期的，说明在fig.10.this样品会给有功功率的测量.3）频率、相位角和功率因数：电源波形的频率可由零点和功能之间的时间段相互决心找到频率给出了方程（3）。Frequency(F)=1/Timeperiod(T)-(3)在同一时刻的电压和电流波形的过零点，可以发现相位角。差异零交叉点之间的相位角可以在时间上，它可以被转换成相位角的方程（4）。Phaseangle(PA)=TimeDifference*360/TimePeriod-(4).功率因数可以通过考虑电压和电流之间的夹角的余弦值来确定。即相位角。在方程（5）中给出了相位角的表达式（）PowerFactor(P.F)=Cos(phaseangle)(5)发现这三个参数的相关软件算法示于图。它还包括一个单独的算法来表示领先，以及滞后的功率因数。4）谐波（总谐波失真）：谐波是基频以外的频率。通常它们是基本频率的倍数。他们造成电源中的干扰，会产生热，噪音等，也导致非正弦波形式，可能会损坏电气设备。找到他们，一个数学的方法快速傅里叶变换（FFT）分析法，以及总谐波失真（THD）给出了各次谐波。在一个模拟电压或电流波形的谐波分量的计算说明图。最初，从电压或电流传感器输出信号给ADC采样作为它的每个周期的128个样品，采样数据进行FFT分析处理计算谐波。FFT分析的主要目的是将时域信号转换成频域表示这是由方程（6）。其中k=0,1,2，的n-1n是时间域和频率域的顺序依次是。在这种情况下，n为128的样品的数目为代表的。转换到频域后，我们将得到的表达。然后谐波的幅值和相位可以通过方程（7）。时域信号转换到频域中，它是要知道即使样品和奇怪的样品分别处理，最后结合如图有趣。软件算法的FFT分析显示图的实现。最初给出的数据是在倒位序如图，然后进行第一阶段，在第一组和第一只蝴蝶。在计算该蝶后，它将完成剩余的所有其他蝴蝶位于不同组的不同阶段，每一个以上的算法，并给出了在频域中的谐波的值。本文提出的原型，它可以测量1到63次谐波和总谐波失真（THD）。这个总谐波失真是指对所有谐波分量的基波功率给出了方程的力量总和的比值（8）。它表示在信号中存在的完整的谐波失真。对于测量，具体的电压波形THD只有百分比是液晶显示了。IV.样机开发与调试V.样机开发与调试以上讨论的第二部分和第三部分介绍了在这个原型中使用的硬件和软件编程。在这一部分中，所提出的工作显示所有组件连接在图及其描述整个原理进行了详细的讨论。在图中，我们观察到一个单相电源通过电压和电流传感器连接到一个负载的电能质量参数被发现。负载可能是一个电阻，电感，电容或任何组合。稳压电源是提供以生成+12V，12V偏压传感器和+5V供电的MSP430微控制器，LCD显示。正如在第二节中已经讨论的，运算放大器电路是用于三个目的，即过零检测，信号增强和信号反演。这三个回路电压和使用一个四通道lm324op-amp电流。这三个电路的输入是相同的