文献翻译原文-基于Web的分布式电能质量评估测量系统

Aweb-baseddistributedmeasurementCastillejoElectronicsAlgeciras,VinciReceivedinrevisedform4January2010ishighlysensitivetoPQevents.ControlandsupervisionofanindustrialprocesshasmainlyAssessmentofVQandpowerdisturbancesinvolveslookingatelectromagneticdeviationsofthevoltageorcur-rentfromtheidealsingle-frequencysinewaveofconstantamplitudeandfrequency.VQproblemscommonlyfacedbyfacilitiesoperationsincludetransients,sags,swells,surges,outages,harmonics,andimpulsesthatvaryinquantityormagnitudeofthevoltage1.Aconsistentsetofdefinitionscanbefoundin2.Thequalityofthepower0263-2241/$-seefrontmatterC2112010ElsevierLtd.Allrightsreserved.qThisworkwasfundedandsupportedbytheAndalusianGovernmenttowardstheResearchUnitPAIDI-TIC-168,andbytheSpanishMinistryofScienceandInnovationviatheprojectTEC2009-08988.*Correspondingauthor.Address:UniversityofCdiz,ResearchunitPAIDI-TIC-168,AreaofElectronics,EPSA,Av.RamnPuyolS/N,E-11202Algeciras,Cdiz,Spain.Tel.:+34956028020;fax:+34956028001.E-mailaddress:juanjose.delarosauca.es(J.J.G.delaRosa).URL:http:/www.uca.es/grupos-inv/TIC168/(J.J.G.delaRosa).1MainResearchersoftheResearchUnitPAIDI-TIC-168.Measurement43(2010)771780ContentslistsavailableatScienceDirectMeasuremjournalhomepage:www.elsevierdoi:10.1016/j.measurement.2010.02.009Asmoreandmoreelectronicequipmententertheresi-dentialandbusinessenvironment,thesubjectsrelatedtoPowerQuality(PQ)anditsrelationshiptovulnerabilityofinstallationsisbecominganincreasingconcerntotheusers.ThetwomainaspectsofPQare:C15TechnicalPQ,whichincludes:Continuityofsupplyorreliability(sustainedinterruptions)andVoltageQuality(VQ),thatisvoltagelevelvariationsandvoltagedisturbances.lated(suchasthedelaytogetconnectedtothegrid,etc.)aswellascommercialservicesforenergyretailtoregulatedcustomers.Sustainedinterruptions,whichoccurwhenvoltagefallstozeroformorethanoneminute,arethereliabilityprob-lemwithwhichmostelectricityconsumershavethegreat-estdirectexperienceandarethekeyphenomenameasuredintraditionalutilityservicequalityandreliabil-itystatistics.IndicessuchasandSystemAverageInterrup-tionFrequencyIndex(SAIFI)andCustomerAverageInterruptionDurationIndexrespectively(CAIDI),donotcapturePQperturbations.Accepted17February2010Availableonline21February2010Keywords:DistributedmeasurementsystemPowerQuality(PQ)Smartsensors1.Introductionbeenfocusedontheelectricalprotection,andlittleattentionhasbeenpaidtothequalityoftheelectricalsupplies.Nowadays,measurementandcommunicationssystemshaveadvancedtoenabletheinstallationofweb-basedsensorswithinaPQassessmentscenario.Inthissense,thispaperpresentsaninnovativelow-costmeasurementsystem,aswellasinvestigatesthechallengesandtrendsinthedevelopmentofdistributedPQmeasurementsystemsusingsmartsensors.C2112010ElsevierLtd.Allrightsreserved.C15Commercialservicesassociatedtothewiresareregu-Articlehistory:Received17June2008Industriessystemsareshiftingtowardalmostentirelysophisticatedelectronicdevices.PowerQuality(PQ)analysisisgettingimportancefortheeconomybecausethisequipmentassessmentqJuanJosGonzlezdelaRosaa,b,*,1,AntonioMorenoVctorPallarsLpeza,c,JoseAntonioSnchezaResearchGroupPAIDI-TIC-168:ComputationalInstrumentationandIndustrialbUniversityofCdiz,AreaofElectronics,EPSA,Av.RamnPuyolS/N,E-11202cUniversityofCrdoba,AreaofElectronics,CampusdeRabanales,LeonardodaarticleinfoabstractsystemforelectricalpowerqualityMuoza,c,1,AuroraGildeCastroa,c,c(ICEI),Andalusia,SpainCdiz,Spainbuilding,E-14071Crdoba,S/locate/measurement772J.J.G.delaRosaetal./Measurement43(2010)771780supplydeliveredbyutilitiesvariesconsiderablyandde-pendsonanumberofexternalfactors.Thingslikelight-ning,industrialpremiseswhichapplyandremovelargeloads,non-linealloadstresses,inadequateorincorrectwir-ingandgroundingorshortcircuitscausedbyanimals,branches,vehicularimpactandhumanaccidentsinvolvingelectriclines.Somepowerprovidersseektodeterminecompliancewithlimitsestablishedinstandardssuchas3.Amongallcategoriesofdisturbances,thevoltagesag(dip)andmomentaryinterruptionarethenemesesoftheautomatedindustrialprocesses4.Voltagesagiscom-monlydefinedasanylowvoltageeventbetween10%and90%ofthenominalRMSvoltagelastingbetween0.5and60cycles.Ontheotherhand,voltageswells(whicharenotsocommon)donotnormallydisruptsensitiveload,butcancauseharmtoequipment.Momentaryvoltageinterruptionisanylow-voltageeventoflessthan10%ofthenominalRMSvoltagelastingbetween0.5cyclesand3s.Voltagesagscanbecausedbynaturalevents(e.g.,treesfallingonpowerlinesorlightningstrikinglinesortrans-formers),utilityactivities(e.g.,routineswitchingopera-tionsorhumanerror),orcustomeractivities(e.g.,startingoflargemotors).Voltagesagsatacustomerbusaredifferentdependingtohislocationintheelectricalnet-work5.BecauseoftheshortdurationofthesePQevents,residentialcustomersarerarelyawarethataVQeventhastakenplace.However,formanyindustrialcustomers,theyposeafarmoresignificantproblemthanoutagesbecauseoftheirmuchgreaterfrequencyofoccurrenceandoverallbecauseofthattheirincidencecancausehoursofmanu-facturingdowntime6.Ithasbeendiscoveredthatthe85%ofpowersupplymalfunctionsattributedtopoorVQarecausedbyvoltagesagorinterruptionsunderonesec-ondofduration.Somemajorproblemsassociatedwithunregulatedlinevoltages(inparticular,long-termvoltagesags)includeequipmenttripping,stalling,overheating,andcompleteshutdownsofsensitiveequipmentifitisdesignedtooper-atewithinnarrowvoltagelimits,oritdoesnothaveade-quateride-throughcapabilitiestofilteroutfluctuationsintheelectricalsupply.Thesesubsequentlyleadtolowerefficiencies,higherpowerdemand,highercostforpower,electromagneticinterferencetocontrolcircuits,excessiveheatingofcablesandequipment,andincreasedriskofequipmentdamage.Theneedforlinevoltageregulationstillremainsanecessitytomeetdemandsforhighindus-trialproductivity.Thereareseveralconditioningsolutionstovoltageregulation,whicharecurrentlyavailableinthemarketplace.AmongthemostcommonareUn-interrupt-iblePowerSupplysystems(UPS).Recently,newtechnolo-gieslikeCustomPowerdevicesbasedonpowerelectronicconceptshavebeendevelopedtoprovideprotectionagainstPQproblems7.However,themostsignificantbarriertoimprovingthePQisthelackofcontemporaneousandhistoricalPQdata8.ThenormIEC61000-4-309hasbeenestablishedtodefinethemethodsformeasurementandinterpretationofVQparameters10.Foreachrelevanttypeofperturba-tionameasurementmethodisestablished.Twodifferentclassesofmeasurementdevicesaredefinedaccordingtotheaccuracy.ClassAdevicesareusedwhenprecisemea-surementsarenecessary.Forexample,forcontractualapplications,verifyingcompliancewithstandards,resolv-ingdisputes,etc.ClassBmeasuringinstrumentsareusedtodeterminestatisticalvaluesandregulate/correcterrors(troubleshooting).ApropermonitoringsystemthatiscapableofobservingPQphenomenaonacontinuousbasisisneededsincetheoccurrenceofapowerdisturbanceishighlyunpredictable10.ThemaincharacteristicsandtrendsinadvancedPQmeasuringinstrumentscanbefoundin1113.Lastyearssomeexperimentalsolutionshavebeenproposed.In14thesystemisimplementedbytheuseofstandardLabViewTCP/IPtechnologyonapartialbuildinglow-voltagenet-workthatcouldbeasimplifiedrepresentativemodeloflargernetworks.Asbefore,thesystemhardwarein15consistsofseveralPCs,eachonehostingadataacquisition(DAQ)board,linkedtothepowersystembyavoltagetransducer.ThesoftwareimplementsdifferentVirtualInstruments,usingthewellknownNILabViewgraphicalprogramminglanguage.Moreover,manyutilitiespresentlyutilizededicatedPQmonitoringdevicesonthehighandmediumvoltagestationstodetectpowerqualityevents16.OneofthemilestoneapproacheswasoriginallydevelopedfortheElectricPowerResearchInstituteinthelastdecade17.However,themostwidelyextendedinfra-structureinstalleduptonowis18.Ontheotherhand,manyautomatedfactoriespresentlyutilizededicatedPQmeasurementdevicesbutonthepointofcommoncou-pling(PCC)andwiththeexclusivepurposeofdeterminingtheutilityresponsibilityinPQevents.Littleempiricalresearch,however,isavailablefromtheperspectiveofintegratingdistributedmeasurementinsidetheplant.Inbrief,isneededalow-costsystemcapableofobservingPQphenomenaonacontinuousba-sis.Thisisimperativesincemostofthehiddencausecomefromunlikelysourcessuchasoperationofexistingfactoryequipmentorincorrectwiringschemes.Whileallmajoreventscanbecaptured,thiscouldresultinexces-sivedatafromnon-criticalevents.Themaintenanceengi-neermustthensortthroughthisdatatoanalyzethePQdisturbance.Manualmethodsareexpensive,timecon-suming,anderrorprone.Customsoftwaredevelopedforeachsiteforanalyzingdata,again,canbeveryexpensivetodevelop,maintain,and-dependingontheirunderlyingarchitecture-difficulttoexpand.Thus,design-ingasystemthathastheabilityofanalyzing,condensingandinterpretingvoluminousrawdatasothatlevelscanbeassessedagainstlimitsandcanbeeasilyexpandedwouldbecomethemostsignificantchallengeinthePQmeasurementarena.Thispaperintroducesaninnovativeandextremelylow-costPQweb-basedmeasurementsys-tem,whichissuitableforcontinuousPQmeasurementinanindustrialorcommercialplant.Thepaperisstructuredasfollows:Section2summa-rizesthestrategydevelopedinthedesign.Sensorconfig-urationisdescribedinSection3.TheinvolvedmeasurementerrorsaredetailedinSection4.TimingprotocolscompatibilityisjustifiedinSection5.SystemoperationisdescribedinSection6.Finally,conclusionsaredrawninSection7.J.J.G.delaRosaetal./Measurement43(2010)7717807732.Designstrategy2.1.RequirementsTheweb-basedmeasurementsystemactsasasentinelthatreliesonwidespreaddeploymentofanumberoflow-costsensors,termedPQwatch,throughoutthedistri-butionnetworkoftheplant.TheycontinuouslymonitorenergyconsumptionaswellasmeasuredetaileddataonPQevents,includingoutages,blackouts,brownouts,inter-ruptions,andshort-durationdisturbances,suchasvoltagesagsandswells.Inadditiontothesefeatures,advancedfunctionsforenergysavingsandimprovingEnergy-UseDiagnosticscanbeimplemented.ItisalsopossibletogatherallmeasuredPQdatafromvarioussitesinsidetheplant.DatafromPQwatchsen-sorsallowstoidentifyPQeventsanddeterminetheirim-pactonindividualmachines.Inaddition,becausethedatafromallmonitorsareuploadedviatheinternet,wecancorrelatedatafrommultiplemonitorstodeter-minewhethereventsrecordedatonesiteweredetectedorhadimpactelsewhere.Fromthisinformation,wewilldeterminatetheoriginandcauseoftheeventandtheef-fectoftheeventoncompanyprocesses(downtimecosts),drawingconclusionsabouttheresponsibilityoftheutility.PQdisturbancescanrangefromhighfrequencyim-pulsescausedbylightningstrikes,tolong-termsustainedover-voltagesresultingfrompoorvoltageregulation.Thecapabilitiesofthemeasurementdevicewillalsoinfluencethechoiceofwhichparameterstomeasure.Broadlyspeak-ing,thesesensorswillmeterthefollowingquantities:volt-ageandcurrent,activepower,apparentpower,totalreactivepower,fundamentalfrequencyreactivepower,en-ergyuse,costofpower,powerfactor,totalharmonicdis-tortionofthesupplyvoltage(THD),alsotheninemostimportantharmonicvoltages,frequencyofthesupplyvolt-ageandvoltageunbalancebetweenthethreephases.Addi-tionalmeasurementsarevoltageswells,sagsandinterruptions.Therecordingdensitycouldbesetassomeseconds,minutesorhours.ThesimplestversionofthePQmonitorwouldrecordonlyaforementionedpowers,voltageandcurrentvariations.Onlineandoff-lineanalysishavetobeconsideredasimplementationoptions.Onlineanalysisisdevotedtotheincidentsthatneedimmediateattention(forexamplesagsorinterruptions).Theonlinedataanalysiscanbeper-formedwithintheinstrumentitselforimmediatelyuponcollectionoftheinformationatacentralprocessingloca-tion.Inordertoreducetheoverburdendata,theeventaregroupedincategories:transients,interruptionsorvolt-agesagsandswells.Asexistthepossibilityofreceivingseveralincidentalarmatthesametime,itcouldbeneces-sarytheuseofsomekindofdistributionscoreboard”algorithmthatautomaticallyclassifieseventsrankingimportance.Thiscouldbedonebytheuseofdifferentcri-teria,e.g.maximaltimeduration,maximalmagnitudevar-iationormaximalenergyvariation.Regardingtheoff-linePQanalysis,thefollowinginfor-mationisusuallyincludedinareport:C15Statisticsofthesteady-statevariations(voltagelevel,harmonics,unbalance,orflicker).C15StatisticsoftheEventresultingfromincidents(sags,short-interruptions,swells,ortransients).C15Identificationofthelikelycauseofthepowerdisturbances.C15Characterizationoftheelectromagneticcompatibilitylevelofequipmentsandinstallation.C15Recommendationsforcost-effectivemitigationandmaintenancesolutions.Inaddition,itisnecessaryascaledapproximationinthisreportingactivity,differentiatingbetweenthedetailedlocalapproximationtoaglobalpointofview.Thus,thedevelopmentofsystematicproceduresforPQdataman-agementsupportsingeneralthereportingofdistributionPQsurveys:C15Sitereport(e.g.detailingsufficientlythequalityreports,planningofcompensationofreactivepower,instruc-tionsfortheuseofvariousequipment).C15Plantnetworkreport(e.g.givingsimplesiteindicesforallmeasurementpoint,forinvestmentplansandman-agementofvoltagedropsandotherdisturbances,andofferingtheabilitytocorrelateeventsrecordedatgeo-graphicallydispersedlocations).Inallofthecases,thereportisdifferentforvariationsandevents,withvariationssiteindicesbeingakindofaverageandeventsiteindicesbeingakindofeventcount.2.2.ThemethodThemethodimplementedintheweb-basedsystemfol-lowsthethreesteps.First,toobtainsampledvoltageswithacertainsamplingrateandresolution.Foreveryevent,voltagesamplesareobtainedwithasamplingrate(estab-lishedassamplespersecondorpercycle)andwithares-olutiondetermined,statedasthenumberofbits.ManycommercialPQmeasurementinstrumentshavesamplingratesof256samplespercycle,sincethemajorityofPQeventshavefrequencycontentsbelow5kHz.Oscillo-graphicdataprovidesthemostdetailedinformationforengineeringtroubleshooting,withthehandicapofmemorystorage.Secondly,itcalculateseventfeaturesasafunctionoftimefromthesampledvoltages.ThischaracteristicscanincludeRMSvoltages,RMScurrents,negativeandzero-se-quenceun-biases,realandreactivepower,harmonicdis-tortionlevelsandindividualharmoniccomponents.Forthree-phasemeasurements,thethreevoltageswilltypi-callygivedifferentcharacteristicsversustimeforthethreephases.Fromthesethreefunctionsadditionalcharacteris-ticsareneeded.Severalmethodshavebeenproposedtoachievethisgoal.Although10ismainlybasedonsin-gle-phasemeasurements,formulti-channelmeasure-mentstheworstphaseistakenforfurtheranalysiswhencalculatingsingle-eventindices.Thiswillbeanalyzedbe-low.Asacomplement,theeventdurationmeasurementcanbestartedononechannelandterminatedonaPQdatacanberecalculatedandpackedintoindicesthatofamomentaryinterruptioneventdefinedbythefinal774J.J.G.delaRosaetal./Measurement43(2010)771780draftofIEEEP1366.Toconsidertheimpactofvoltagesagstoanindustrialload,someutilitieshaveadopteda15-minor30-minaggregationperiod.However,a1-minaggrega-tiontimeperiodagreeswiththedefinitionoftheminimumlengthofasustainedinterruption.SpatialaggregationisusedtoreducethenumberofRMSvariationmeasurements,thetemporallyaggregatedmeasurementsfrommultipleinstrumentsarecombinedintoasinglemeasurement.Forexample,thistypeofaggre-gationwouldbeinterestedincomputingRMSvariationindicesatasinglesubstationthatismonitoredviamultiplebuses.3.PQsensorconfigurationSensorscanbeclassifiedintoelectrical,mechanical,thermal,radiation,optical,magneticandchemical/bio-chemicalsensors.Sensorsarelabeledasmicro-sensor,nano-sensororsimplysensoraccordingtotheirphysicaldimensions.Theboundariesbetweenthesedifferentcate-couldbegatheredandstoredbytheSCADA.Thisincludesvoltagesagsandswellsinmagnitudedurationtables,transientstableswhichincludemaximumvoltage,tran-sientdurations,andtransientfrequency,ormagnitudedurationscatterplotsbasedonCBEMA,ITIC,oruser-spec-ifiedmagnitudedurationcurves19.Inaddition,itcouldbeprovidedstatisticalanalysisofvariousminimum,aver-age,maximum,standarddeviation,count,cumulativeprobabilitylevels;concretelythisisnecessaryforthehar-monicindices.Singleindicesgivetheenduseranaccuratediagnosisofwhathasoccurredonthesystemfortheoff-lineanalysis.2.3.AggregationAnaggregatePQeventisthecollectionofmeasure-mentsassociatedwithasingleoccurrence,whichislabeledforcomputingpurposes.Theaggregateeventassociatedwithafaultgatherstheassociatedmeasurements(magni-tude,duration,etc.).Manycustomerdevicesandprocessestripormiss-operateontheinitialsagassociatedwithafault.Subse-quentcircuitprotectionoperationswouldhavenotcausedsubsequentmiss-operationsbecausetheprocesshadnotyetbeenrestarted.Consideringmultipleeventsresultingfromthesamepowersystemoccurrenceindividuallymaydistorttherepresentationofthetruestateofthesys-temservicequality.Thus,anaggregationperiodshouldbechosenrelativethetimingsequencesofprotectionschemes.Thetimelengthchosenforaggregationisarbi-trary.A5-minperiodconcurswiththemaximumlengthdifferentchannel;thisisthemethodproposedforsagscharacterizationandcanbeextendedtointerruptionsandswellstoo.Bothproceduresreduceover-countingandcanbeconsideredasaphaseaggregation”technique.Finally,themethodcalculatessingleindexesfromtheeventandvariationscharacteristics.Thekeypointconsistsofretrievingdatainthetimeneededfortheanalysis.Then,goriesareflexible.Inpowermeasurement,sensoroutputscanbevoltageorcurrentsignals,whicharetraditionallyassociatedwithanalogsensors.Theoutputtedanalogsig-naliscontinuouslypushedtoacentralcontrolblockforla-terprocessingthroughashieldcable.Goingonestepfurtherappeardigitalsensors,theseearliersolutionscanreadtheanalogsignalandtransformitintoadigitalformfortransmission.Inindustryanewtendencyinthefieldofsensorapplicationcanbeobservedofgettingmoreinformationfromonlinesensorsignalanalysis.Thoughthedigitalsensorsarecapableofnetworking,theywillbringheavyburdenstocentralserverstoprocessdataandnetworkloads.Thus,bothkindofsensorsarecalleddumb”sensorduetolackoftheprocessingcapabilityatthesensorsite.Intelligenceinthecontextofasensorisnotcomparablewithhumanintelligence.Itindicatesonlythatthesensorisdifferenttoonethatsuppliesjusttherawdata.Thetermsmartisalsousedinsteadofthewordintelligent.SmartSensorsystemsarecomposedofthreeparts:communications,dataacquisitionandsensors.Itistodaypossibletohaveallthreepartsonasinglechipatalowcost20.Comparedtodumpsensors,Smartsensorshavetheirownbrains”andcanmakedecisionsbythem-selves.Theyusuallyoutputdigitalvaluesinwhichtheembeddedmicroprocessorcoremayperformcalibrationsandscalin