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THEADVANTAGESOFCONTINUOUSMONITORINGOFPOWERLINECARRIER(PLC)CHANNELSAPPLIEDTOPROTECTIONSYSTEMS

RogerRay,AlanJayson&RayFella,PowerCommSolutions,LLC,JeffreyEBrown,Georgia

Transmission;NeilStone&RobertBaldwin,SouthernCaliforniaEdison

INTRODUCTION

Thecriticalnatureofthepowertransmissionsystemtodaymakesitimperativethatutilitieskeepupwiththedemandofroutinemaintenanceoftheprotectionsystem,aswellas,monitoringthehealthofthesystem.Inthismanner,thereliabilityofthesystemcanbeassured.Thispaperwilldescribemethodsbywhichthesystemcanbemonitoredandhowthedatacanbeusedtopredicttheneedformaintenancebeforesystemfailureoccurs.

Todaytheprotectionsystemismadeupofmicroprocessorrelays,whichcanmonitortheirhealthandalarmifthereareproblemswiththesystem.ManyoftheseprotectionsystemsemploytheuseofPower-Line-Carrier(PLC)equipmenttoaidinthesimultaneousdetectionofthefaultatalllineterminalstoclearthefault.ManyofthesePLCsystemsdonotcanmonitorallaspectsoftheirhealth.Also,wehavenothadtheabilityofbeingabletohaveanindependentdevice(suchaswhataDigitalFaultRecorder(DFR)doesforthepowerfrequencyequipment)thatcanmonitortransientresponsesoftheRFportionofthePLCsystem.Ifthistypeofequipmentwereavailable,anyabnormaltransientbehavioroftheterminalequipmentaswellasthecommunicationspathcanbemonitoredandproblemscanbedetectedbeforetheybecomeanissueaffectingthereliabilityoftheprotectionsystem.Inaddition,whenunexpectedsystemeventsoccur,datawillbeavailableforindepthanalysisofthecommunicationpaththatcanbesynchronizedandcomparedtootherdevicesonthesystem.ThisdatacanbeusedtoassistinanalyzingwhatisoccurringontheRFpathwhenaPLCissue(e.g.carrierholes)hasoccurred.

PRC-005-002PowerSystemMaintenanceStandard[4]nowrequiresutilitiestoperformmaintenanceontheirProtectionSystemsatspecificmaximumintervalsbasedonthelevelofmonitoringthatexists.Complyingwiththisrelativelynewstandardcanpotentiallybeverycostlytoautility.ADFRtypeofcontinuousmonitoringsystemforthePLCsystemcoulddrasticallyreducethecostoftheperiodicmaintenance.Informationsuchasreflectedpower,levels,margins,andevensystemnoiseatcarrierfrequencycouldbemaintained.Whenamaintenancecycleapproachesrealtimedatafromthemonitoringsystemwouldbecapturedandcomparedtoarchiveddatatodeterminewhatmaintenance,ifany,isneeded.Thisreal-timemonitoringwillreducesystemdowntimewhileminimizinghumaninteractionwithlivesystemsthatsometimesleadtounexpectedoperationalincidents.

FUNCTIONSIMPORTANTTOAPLCMONITORINGSYSTEM

StandingWaveRatio(%RFLP)/%ReflectedPower%RFLPMonitoring

Monitoring%RFLP/%ReflectedPowerprovidesvaluableinformationtoaPowerLineCarrierprotectionuser.The%RFLPofaPLCsystemisaffectedbychangesinImpedanceterminatingthetransmitter.WhenchangesoccuronthePowerLineCarriersystemtheyaretypicallyacombinationoftheresistive,capacitiveandinductivecomponents.KnowingtheImpedanceandPhaseAngleofthe%RFLPiscriticaltothediagnosisofthesechanges.Havingadevicethatis

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capableofmeasuringboththeimpedanceandphaseanglewiththe%RFLPmeasurementisimportantfortroubleshootingthechange.Anychangesintheseelementsprovidescluestowhatmayhavecausedthechangeinthereflectedpowerreading.Forexample,aPowerLineCarrierMonitoring(PCM)devicelocatedperFigure11withazero%reflectedpowerreadingshouldmeasureanimpedanceof50𝛀withazero-degreephaseangle.

AnincreaseintheimpedanceofthemeasurementmeansthattherewasanincreaseintheimpedanceoftheentirePLCsystem.Anegativephasetellstheuserthattherehasbeenachangethathascausedthesystemtobecomemorecapacitivetothatfrequencyoriftheangleispositivetheimpedancehasbecomeinductive.Someexamplesofwhatthesedetailedmeasurementscanindicatearelinetrapfailures,linetunerproblems,overalllineimpedancechangesforvariationreasons.

Ifonlythemagnitudeorpercentreflectedpowerisknown,thereisnowaytoknowwhatismismatchedorwhatmayhavechangedontheoverallPLCsystem.

Table1showsexamplesthatallrepresenta10%reflectedpowerreading.Notethateachhavesignificantlydifferentresistive,capacitiveandinductivecomponents.Havingtheimpedanceandanglemeasurementsnowprovidesaclearerpathtowhathaschangedintheoverallsystem.

Table1-ImpedancesResulting

ina10%ReflectedPower

Z FAngle

80.75𝛀 +23.95o63.59𝛀 -32.71o39.37𝛀 +32.75o36.68𝛀 -30.94o

PLCReceiverTypeMeasurements

HavingamonitordevicethatreplicatesthecharacteristicsofaPowerLineCarrierreceivernotonlyprovidesasecondwaytodetectproblems,butthisindependentdeviceisnotrestrainedbytheextraprotectionsandtimersneededtomeetthedesiredsecurityanddependability.Anindependentreceiver/monitoringdevicecanbesetmoresensitivetocaptureactualrawmeasurements.Thisiscriticalinformationthattheregularreceivermaysee,butdoesnotreactto,basedonitsschemeand/orindividualprotectivesettings.Amoresensitivedevicecanprovidevaluableearlydetectiontopotentialfutureproblemsbeforetheyoccur.Addinglongtermtrending(hourly/dailymeasurements)forLevelorReflectedpowerenhancestheopportunitytoavoidpossiblemis-operationsinthefuture.TrendingcanalsoprovideinsighttoshorttermeventsthatnegativelyimpacttheCarriersystem,likeadverseweatherconditions.TimeSynchronizationoftheeventrecorderisalsovaluablewhencomparingeventlogsbetweenvariousprotectivedevicesinthesystems.

SpectrumAnalysisUsingFastFourierTransform(FFT)

UsingFFT’s:Withtimedomainviewing(Oscilloscope)itisnotpossibletoseetheindividualsignalyouareinterestedinbecauseitshowsacompositeofallthesignalspresent,includingnoise.Toviewmultiplesignalsatthesametime,usingfrequencydomain(FFT’s)isthebestway.

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Withatime-domaindisplayoneisviewingamplitudeontheYaxisandtimeontheXaxis).WithafrequencydomaindisplayoneisviewingamplitudeontheYaxisandfrequencyontheXaxis.

Thesignalissampled“N”times(totalsamples),atafrequencyhighenoughtoproduceallfrequenciesineachband,andstoredinabuffer.AnFFTisrunonthestoredsamplesandanamplitude/frequencyplotisproduced.AnexampleofatimedomainplotvsafrequencydomainplotisshowninFigure1below.

Figure1-Timedomainvsfrequencydomainplots

EventDrivenFFT’s:

EventdrivenFFT’SprovideanopportunitytoseewhathasoccurredontheRFpathduringaspecificevent.Examplesofsomeoftheseeventsarelossofsignal,receivedguardortrip,%RFLPoutofrange,etc.Thecapturedspectralanalysisprovidesmoreinsighttowhatmayhavehappenedwhenoneofthesespecificeventsisrecorded.Forexample,somelossofguardeventsrecordedbyPLCreceivers,canbecausedbyvariousevents,notjustbythelossoftheactualsignal(Guard).Atransientnoiseeventcancausethesignaltonoiseratiotodecreasesignificantlywhichcouldcausethereceivertoindicatealossofguardeventhoughtheguardfrequencyisstillpresent.

Figure2showsanFFTcaptureofasingleFSKtransmitterinitsnormalstate.Figure3showsacaptureofatransientnoiseeventonthesamelinewiththeguardfrequencystillpresent.NotetheGuardfrequencyisstillpresent,althoughthesignal-to-noiseratioisvisiblyworse.Insomecases,thistypeofeventcancauseareceivertoclamp(notpermitguardortrip),whichcanberecordedbythePLCReceiverorprotectiverelayitstiedasalossofguardevent.AnFFTcaptureofthiseventhelpstheuseridentifythatthetransmitterandreceiverseemtobeoperatingasexpectedandthussavessignificanttimebyeliminatingthetransmitterandreceiverasthecauseoftheproblem.

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Figure2-ExampleofaTransmitterinitsNormalState

Figure3-ExampleofaNoiseEvent

SpectralAnalysisCapturewithOverlay

WhencommissioningaPCMdevice,theabilitytocapturearealtimeSpectralAnalysisoftheChannelcanbeanincrediblyusefultoolinanalyzingchangesorintrusionstotheknownfrequenciesontheline.Areal-timecapturepermitstheusertheabilitytoidentifyallfrequencies,levelsandnoisepresentatthetimeofcommissioningandverifythattheyareknownentitiesandacceptablelevels.Ifthis“commissioning”oracceptablestateSpectralAnalysiscanbesavedasareferenceorbaseline,theusernowhasaninvaluabletoolforfuturesystemanalysisor

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troubleshooting.WhentheuseraccessesthePCMdeviceonalaterdateandcapturesanewSpectralAnalysisofthesameChannelandthenimportstheoriginalcaptureasanoverlay,theycanseeanychangesthatmayhaveoccurred.Figure4showsaninitialRealTimeCaptureofaChannelwith3frequenciespresent.

Figure4-InitialRealTimeCapture

Figure5-InitialCaptureOverlaidwithaLaterCapture

Figure5showsapresentSpectralAnalysisCapturewithanoriginalcaptureoverlaid.Thegreencapturerepresentstheoriginalcaptureandtheyellowrepresentsthepresentcapture.Notethatthenewcapturehasa4thfrequencythatdidnotexistattimeoftheoriginalcapture.

Thisoverlaytoolcanbeusedtoassistandidentifymanypotentialissuesbeforetheybecomeactualproblemsormisoperations.Forexample,whenanymaintenanceornewinstallsareperformedonlyafewbussesawayfromasitebeingmonitored,oftentimefrequenciescanbleedthroughandshowupathighenoughlevelstopotentiallyinterferewithanexistingprotectionchannel.Usingtheoverlayprocessatanytimecaneasilyhelpidentifypotentialproblemsquickly.Thereisalsothepossibilityofdetectinglinetrapfailuressimplybecauseanewfrequencyhasappearedinthepresentrealtimespectralanalysiscapturethatoncedidnotexist.Knowingthatunexpected

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frequencyvaluepermitsausertheabilitytoidentifywhereintheirsystemthatfrequencymaybecomingfrom.

LongTermMonitoring–MaintenanceExtension–AssistwithNERCCompliance

APCMinstalledpermanentlyprovidestheutilityamechanismthatcanbeusedtomoreeasilycomplywithPRC-005-002maintenancecycles,butcanalsoreducecosts.Inaddition,onceinstalled,thePCMcanbeaccessedatanytimeeitherremotelyorlocallytoreviewmeasurementswithouttheneedforaPLCsystemoutage.ApermanentlyinstalledPCMdeviceislikehavingmultipleinstrumentsinthesystemalways.ThePCMcanbeusedtorecord“AsLeftData”atcommissioningoratanyfuturetime.This“AsLeft”datarepresentsthepresentmeasurementsofthePLCchannelsandwhenconnectedtoasatelliteclockcanrepresentamaintenancetest.ThisAsLeftreadingcannotonlybeusedformaintenancetesting,butalsobecomesapermanentelectronichistoryofallmaintenancemeasurementsperformedwithtimeanddatestamp.

APPLICATIONOFAMONITORTOTHEPLCSYSTEM

HowLocationofthereflectedPowerMeasurementAffectstheResults

BeforeadiscussionabouttheapplicationofamonitortoaPLCsystem,itisimportanttoknowhowthelocationwherethe%RFLPismeasuredwillaffectthereading.Itiswidelyacceptedthatthebestlocationtoperform%RFLPmeasurementsisattheRFinputofthelinetuner.Whenadditionalcomponentslikehybridsareinsertedintothepathbetweenthe%RFLPmeasurementandthetuner,thereadingswillnotbethesame.Commonlocationsfor%RFLPmeasurementscanbeseeninFigure6&Figure7.

Figure6-%RFLPVariationBetweenLocation1&2

Figure7--%RFLPVariationBetweenLocation1&3

Figure8shows%RFLPmeasurementsmadeatbothlocations1&2,withtheImpedanceconstantat50𝛀andavariablephaseangle.

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Figure8-%RFLPDifferencesBetweenLocations1&2:

ImpedanceFixedat50𝛀:VariableAngle

Priortothehavingtheabilitytomeasurethephaseanglecomponentofa%RFLPmeasurement,itwasnotpossibletoknowhowacapacitiveorinductivechangetotheCarriersystemwouldaffectreadingsatdifferentlocationsinthecircuit.ForthemeasurementscenariosshowninFigure6&Figure7,twodifferentmeasurementtestswereperformedforeachfigureshown.ThefirsttestkeptthePhaseAngleconstantatZeroDegreesandvariedtheImpedance.ThesecondtestkepttheImpedanceconstantatapproximately50𝛀andvariedthePhaseAngle.ForFigure6(0⁰PhaseAngle,VariableZ),thereadingsatLocations1&2areessentiallythesame,sonochartwasnecessarytoshowthedifferences.Thatisnotthecasewhenthephaseanglechanges.PerFigure8,measurementsatlocation2arenoticeablyaffectedwhentheImpedancestaysconstantatapproximately50𝛀,butthephasevaries.Notethatwhenthephaseangleisnegative,measurementsatlocation2havedifficultydetectinganychangeinthereflectedpowerreading,althoughmeasurementsatLocation1stillseetheexpectedchangesoccurringonthepath.Inaddition,thistestingalsoidentifiedthatchangingthefrequencyofthe%RFLPmeasurementwillalsoaffecthowdifferentthereadingwillbebetweenthetwolocations.Pertheseresults,sincedifferencesinthereadingsarenotlinear,applyingacorrectionfactortoadevicemeasuringatlocation2wouldnotprovideanyconfidencethatthereadingwouldcorrelatewithreadingsatlocation1.

Thismeasurementdifferencebecomesevenmoresignificantwhenaresistivehybridisplacedinthecircuitalongwithaskewedhybrid(SeeFigure7).Inaddition,whenchangesoccurtoeithertheimpedanceorphaseangle,the%RFLPmeasurementsaresignificantlyaffectedbetweenmeasurementsmadeatlocations1and3.Figure9shows%RFLPmeasurementsmadeatbothlocations1&3,withtheImpedanceconstantat50𝛀andavariablephaseangle.

Figure9-%RFLPDifferencesBetweenLocations1&3:ImpedanceFixedat50𝛀:VariableAngle

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-50 -40 -30 -20 -10 0 10 20 30 40 50

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02468101214161820

-50 -40 -30 -20 -10 0 10 20 30 40 50

%ReflectedPow

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Figure10-%RFLPDifferencesBetweenLocations1&3:0Degrees&VariableImpedance

Figure10shows%RFLPmeasurementsmadeatbothlocations1&3,withthephaseangleconstantatzerodegreesandavariableimpedance.Notethedramaticdifferencesbetweenmeasurementsmadeatlocations1&3whenbothaskewedandresistivehybridareinthecircuit.Inaddition,thereisoneveryimportantmeasurementcomparisonthatisnotshowninFigure10,butiscriticaltoknow.Whenthereisno-loadinthecircuitofFigure7atthetuner,thereisdramaticdifferencebetweenthe%Reflectedpoweratlocations1&3.Anexampleofano-loadconditiononaPLCsystemcouldbeabrokenordisconnectedcoaxialcableinthepath.Asexpected,themeasurementreadingstakenatlocation1are100%reflectedpower.Duetotheinherentimpedancecharacteristicsofatypicalresistivehybrid,themeasurementatlocation3onlyreads16.6%reflectedpower,eventhoughthecableisdisconnectedatthetuner.

Thistestingandresultingdataclearlyidentifiesthattheoptimalplacetomonitor%RFLPisatlocation1only.Measurementsmadeatlocations2or3cannotreturnthesameresultsduetotheaffectsthathybridsintroduceintothecomplexcircuitwhichisaPowerLineCarriersystem.

CommonCouplingSchemes

Sincewearetalkingaboutadevicethatwilldorealtimemonitoringofboththesteady-stateconditionsofthepower-line-carriersystemandcapturingthetransientconditions,wewouldexpecttoseethedeviceappliedsomewhereinthepowerlinecarrierchain.Ifthedeviceisamulti-channelmonitorandbasedonthediscussionintheprevioussection,thenthebestplaceforittobelocatedisinthecoaxjustbeforeitleavesthecontrolhousetogotothelinetuner.ReferenceFigure11.

Figure11-GeneralpreferredlocationforaPCM

ThereareseveralreasonswhythislocationisthebestplaceforthePCM.First,likeaDigitalFaultorTransientrecorderthemonitorshouldbeplacedinalocationwhereitseestheoriginalsignalsentering&leavingthesystem.Second,ifitisamulti-channeldeviceitmustbeatalocationsothat

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itcanmonitorallthedesiredfrequenciesinthesystem.Also,athird,oneofthemostusefulquantitiestobemonitoredisthereflectedpowerfromthelinetuner.Thisquantityismostimportanttowatchsinceitwilltelltheuserthestatusandhealthofthelinetuningsystem.Therefore,asshowninthepreviousdiscussion,thebestplacetoobservereflectedpowerisrightbeforethecoaxcableleavesthecontrolhouse.Atthislocation,thereflectedpowerhasn’tbeenchangedbyanyhybridsinthecouplingchainandthecorrectphaseangleoftheimpedancecanbemeasured.

TheaboveFigure11willsufficeforallapplicationsthatinvolveasinglecoaxleavingthecontrolhousetotheswitchyard.Thereisoneexceptiontothesinglecoaxapproachwhichwillbediscussedlater.

However,whatcanbedonewithapplicationsthatinvolvemulti-phasecoupling.Theseapplicationscangetabitmoreinvolved.First,let’slookatthemostcommonphase-to-phasecouplingscheme.ThisisshowinFigure12.

Figure12-PCMLocationforPhase-to-PhaseCoupling

Atfirstglance,itappearsthattheruleofhavingthePCMinthecoaxialcablerightbeforetheleavingthecontrolhouseisviolated.Inthiscase,iftheterminationonthesplitteroutputsistheclosetoidenticaltheeffectsonanycharacteristicofthesignalbeingmonitoredisveryminimal.Thisincludesthereflectedpower.Let’sdigressandlookatthesplitterschematicinFigure13.

Figure13-GeneralCircuitforaSplitter

Withbothoutputsterminatedthesamethenthereisnocurrentinthe25𝛀resistorandthusthereisnolossesandtheinputsees50𝛀.Thepowerattheoutputofthetransformerisequaltothepowerintothetransformer.Thus,eachoutputseesonehalfoftheinputpowerandthecurrentoneachoutput(referencedtoground)isoutofphasewhichiswhatonewantsinphase-to-phasecoupling.

AsfarasmonitoringtransmittersgoingoutthepoweroutseenbythePCMwillequalthesumofthepoweronthecombinedphases.So,thetransmittermonitoringwillbecorrect.Ifthevoltageis

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receivedfromtheotherendisequaland180ooutofphase,thentherearenoextralossescominginandthevoltageacrosstheinputsideofthetransformerisequaltothesumofthetwophasevoltagesdividedbythesquarerootof2(turnsratioofthetransformer).Eventhoughthisvoltageisdifferentthanthesumofthetwo-phasevoltages,thevoltagethereceiverwillsee(lessthelossesinanyhybrids).Thissameargumentalsoappliestothecurrents,andtheanglebetweenthecurrentsandvoltagesreceivedisnotchangedpassingthroughthesplitter.

Ifthesplitterdoesn’tremainbalanced,thenlosseswillbeincurredthroughitinbothdirections(transmit&receive).Ifthetwophasesdon’tterminateinthesameimpedance,thenlossesoccurduetocurrentinthe25𝛀resistor.Thisisokfromthemonitoringofvoltageandcurrentmagnitudesaswellasangleiftheterminationsareresistive.

Theonlyquantitythathasn’tbeendiscussedisthesplitterseffectonthemonitoredreflectedpower.Again,asabove,thereisnoaffectifthetwophasesterminatethesignalinthesameimpedance.Let’slookatanexample.IfIterminateeachphasein25𝛀andwemeasurethereflectedpowerineachofthephasestheybothwillread46%.Sincetheterminationisthesameforeachphasethenthereisnocurrentthe25𝛀balancingresistoranditisnotseeninthecircuit.Thus,itappearsthatthetransformerisconnectedtotwo25𝛀resistorsinseriesor50𝛀.The50𝛀translatesacrossthetransformerto25𝛀ontheprimary.IfwenowmeasurethereflectedpoweratthePCMlocation,itwillread46%(thesameasoneachphase).

Whathappenstothereflectedpoweriftheterminationsarenotthesame?Whatmightweconsidertobetheworst-casesituation?Let’sconsiderasingle-line-to-groundfaultnearthecouplingcapacitor.Theassumptiontomakehereisthatthefaultwillappearasashortcircuitacrossoneoutputofthesplitter.SeetoFigure14.

Figure14-CircuitforaSplitterwithOneOutputShorted

Onehalfofthetransformeristerminatedwith25𝛀fromoutput1toCTandtheotherhalfwillbeterminatedin75𝛀fromoutput2toCT.Therewillalsobeaninter-actionofcurrentsfrombothoutputsprovidingcurrentinthe25𝛀resistor.Ratherthanattempttosimulatetheresultsinacircuitanalysisprogramitwasdecidedtojustmeasureit.Thereflectedpower,ifmeasuredatoutput1is100%andifmeasuredonoutput2is0%.Theimpedanceattheinputtothesplitterismeasuredat17𝛀ata7.5oangle,whichrepresentsareflectedpowerofabout24%.

Nowifontheotherhand,theoutput1wereanopencircuit,thenthemeasuredimpedanceattheinputtothesplitteris144𝛀ata2.3oangle.NowthemeasuredreflectedpowerattheoutputofthePCMwouldreadabout23%.IneitherofthesecasesthemagnitudeofthereflectedpowermeasuredattheoutputofaPCMlocatedasinFigure12issuchthatanalarmforreflectedpowerinthePCMcouldbesetatabout18%andalarmforeitherofthesecases.Thealarmisnotsensitiveenoughtoalarmforamismatchofsay25𝛀onoutput1and50𝛀onoutput2.InthiscasethereflectedpowerattheoutputofthePCMisonlyabout3%whenthereflectedpowermeasuredatoutput1willbeabout11%.

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TheconclusiontotakeawayfromthisconversationisthattheapplicationshowinFigure12isacceptableformanycarrierconfigurations.Itcanalarmforsevereconditionsononeoftheoutputsofthesplittertransformeranditwillcorrectlymeasurereflectedpowerontheoutputofthephasesonthelineifbothoutputsareterminatedinnearlythesameimpedance.However,iftheuser’srequirementsarecriticalanditisrequiredtohaveanaccuraterepresentationofreflectedpoweronbothphasesthecircuitasshowninFigure15shouldbeused.

Figure15-PCMConfigurationtoMonitorEachPhaseofaPhase-to-PhaseSystem

AMode1couplingschemecangetabitmorecomplicatedtomonitorsinceyouarecouplingtoallthreephases.BecauseoftheaddedSplitterthatisrequiredtodoMode1coupling,IwouldsuggestthattheclearestinformationisobtainedbyusingthreePCMsandputtingoneineachphasepriortothelinetuner.Figure16showsthisconfiguration.

Figure16-PCMConfigurationforMode1Coupling

ApplicationforFullyRedundantCouplingSchemes

Whenapplyingpower-linecarriertoEHVthatarepartofthebulktransmissionsystems,itisoftenconsideredthattworedundantpilotprotectionsystemsbeapplied.Therearemanymethodsbywhichthiscanbeaccomplished.Theissuetobeconsideredhereisthecasewherebothpilotsystemsareonpower-linecarrierandcoupledtothesameline.Couplingschemesthatarefullyredundant(ie,nosinglecomponentfailurewillbutbothsystemsoutofservice)mayberequired.Thisrequirementmakesforamuchmorecomplicatedcouplingsystem.RefertoReference3)formoreinformationonthissubject.

Forthisrequirement,asingle-linetogroundcouplingschemewillnotbediscussedsincethatsystemdoesnotprovideanyredundancyatall.Phase-to-phaseandmode1couplingwillbediscussed.Let’sconsiderphase-to-phasecouplingfirst.Figure17wouldbeadesignthatwouldbeconsideredafullyredundantcouplingsystem.However,thesameshortcomingsapplyhereas

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discussedinthenon-redundantphase-to-phasecouplingabovewiththePCMbehindthebalancetransformer.Inthiscase,thereflectedpowermeasurementwillsuffersincethemonitorpointisbehindacombinationofasplitterandacombiner(hybrid)theerrorbecomesfargreaterthaninFigure12.

Figure17-Phase-to-PhaseFullyRedundantMonitoringSystem

Ifforsomereasononeisnotgoingtomeasurereflectedpower,Figure17wouldbethecorrectwaytodesignthesystem.ThereasonthiswouldbecorrectisthatonePCMismonitoringsystemAandtheotherismonitoringsystemB.Ifontheotherhand,onewantstomonitorreflectedpowerandobtainacorrectreadingyoumustchangethepositionofthemonitoringlocationtothatshowninFigure18.

Figure18-AlmostFullyRedundantMonitoringforPhase-to-PhaseCoupling

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Eventhoughwecan’tcallthisschemeinFigure18fullyredundant,itisasredundantasanysystemsincethelinetuner,couplingcapacitorandlinetrapthePCMsareconnectedisnomoreredundant.Afailureofanyoneofthosecomponentswillcompromisebothsystemssomewhat,butinmostcases,willnotcauseatotalfailureofeitherprotectionsystem.

TheinputtooutputcoaxconnectorinthePCMwillonlyhaveacurrenttransformerinserieswiththecenterconductorandavoltagetransformeracrossthecoaxcentertoshield.Afailureofeitheroftheseunitsaretheonlycomponentsinthemonitoringboxthatcancompromisethesystem.Thesetransformers,beingveryrobustandpassivecomponents,addverylittleprobablyoffailuretotheoverallprobablyoffailureofthelinetuner,couplingcapacitorandlinetrapcombination.So,theeffectofhavingthePCMinthelocationshowninFigure18intermsoffailureprobablyisverysmall.

Figure19-AlmostFullyRedundantMonitoringofMode1Coupling

Figure19aboveshowshowyouwouldarrangethemonitoringforamode1couplingscheme.ThesamecommentsasstatedabovefortheredundancyinFigure18alsoapplytothemode1coupling.RefertoReference3)foradetailedschemeshowingtransformerpolaritiesandconnectionsfortheschemeonFigure19

FIELDTESTINGOFCONCEPTUALDESIGNPCMapplicationTrialforPeriodicMaintenance&meetingNERCrequirementsatGeorgiaTransmissionCo.

Inthepast,periodictestingofpilotsystemshasbeenleftuptotheutilities.Thishasallowedthepilotsystemstobeinvariousstagesofworkingorder.Someutilitieswentoverboardandwereperformingtoomuchmaintenanceandotherswereneglectingtheirsystemsalltogether.Intoday’sregulatorycomplianceledworldthisisnolongeracceptable.Whilesomeminimumrequirementshavebeensetbytheregulations,muchoftheupkeephasstillbeenlefttotheutilities(seeReference[4]).Onlynow,whateveryourmaintenanceprogram,thegovernmentwillaudittheutilitiestoprovethatyourstatedmaintenanceprogramisbeingimplemented.

ThemaintenanceprocesswilltypicallyinvolvetestingoftherelayandPLCsystemtovalidatetheschemeisworkingcorrectly.Thisinvolvesensuringthecorrectsettingsareappliedandthe

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inputs/outputsarefunctioning.Also,thismeanstakingtheschemesoutofservice,havingpeopleatbothendsoftheline,andtakingvariouschannelchecksandreadinglevels.Oncethisinformationhasbeengatheredandevaluated,thedecisionwillbemadewhethertodofurthercalibrationonyourtrapsandtuners.Maintenanceonyourtrapsrequirecrews,manliftsandsystemoutages.Inall,theutilitywillhaveengineers/techniciansandcrewspossiblytiedupfordaysatatimedependingonthesizeofthestationthatisduemaintenance.

WithaPowerLineCarrierMonitoringSystem,periodicmaintenanceofyourpilotschemeswillbecomestreamlinedandmoreefficient.

Let’stakeforexamplearoutinemaintenanceatahypotheticalSpringsubstation(seeonelinediagraminFigure20)equippedwithPCM’s.

2017RoutineatSpringSubstation

Figure20-OneLineDiagramofSpringSubstation

ThreeofthefourtransmissionlineshavePowerLineCarrier.

Spring–KingSt115kvLinehasaDCBscheme.

Spring–LukeWay115kvLinehasaDCUBscheme.

Spring–PeacockAve115kvLinehasaDCUBandTTRxScheme.

Spring–StDillard115kvLineisnon-pilotandprotectedbyZoneProtection.

AllpilotschemesconsistofthelatestPLCequipmentandmicroprocessorrelayswithremoteaccess.

EachpilotschemeisequippedwithaPCM.

Forthisdiscussion,themaintenancewillbebrokenintotwosections.

1. TheControlHouse-ThismaintenancewillconsistofthechecksontherelaysandPLCequipment.ThisinvolvesreadinglevelsandsettingmarginstoensurethePLCsareinworkingorder.Also,theinputs/outputsbetweentherelayandPLCsaretestedtobefunctioningcorrectly.

2. TheFieldEquipment-Thismaintenancewillconsistwiththegatheringofourchannelqualitychecks,specifically,ReflectedPower.Itwillalsoinvolveswappingsignalswiththeremoteterminal.Thistypeofinformationwillbeusedtodetermineifyourtunerortrapneedsattention.

TheControlHouse

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Spring–KingSt115kvLineDCBScheme

DCBSchemesusingON-OFFPLCequemptarerequiredtohaveaperiodiccheckbacktest.ThistestisdonetoverifythePLCsetandthechannelareinbasicworkingorder.AsuccessfultestverifiesthePLCsetiscapableofkeying/receivingablocksignalwhichprovesthatthechannelbetweenthetwostationsisintact.

WithaPCM,onecansimplyremoteintotheboxandgatheryourfirstimportantpieceofinformation.AscanbeseenfromFigure21&Figure22,thePLCsethassuccessfullyshiftedfromOFFtoONstateforthetransmitterandthenaplaybackwasreceivedtoverifytheremoteend.

Figure21-SpectralAnalysisofTransmitterintheOFFState&ONState

Figure22-TheCorrespondingReceiveSignals

Spring–PeacockAve115kvLineDCUBSchemeDCUBschemeshaveanormally“On”GuardSignal.WiththePCMonecanseethesystemshiftingfromGuardtoTrip.RefertoFigure23,Figure24&Figure25.

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Figure23-DCUBinGuard

Figure24-ShiftingtoDCUBTrip

Figure25-DCUBinTrip

Thisspectralanalysiswastakenfromasystemevent.TheDCUBTransmitterisputtingoutasolid10wattsata138.75kHzguardfrequency.

Asatestisinitiated,theradioisstartingtheshiftfromguardtotrip.Informationabouttheschemecanbegleamedfromthisevent.Forexample,inthepilotrelay,theactualrelayoutputisexercisedtothecarrierset,wheretheactualinputonthesetisenergizedcausingittokey.Essentially,theoutputsandinputsassociatedwiththecorrectfunctioningoftheschemeisverifiedbythespectralanalysis.

Heretheradiocompletesitsshiftfromguardtotripensuringusthatlocalendisfunctioningcorrectly.Dependingonthetypeofevent,theremaybeacompanionreceiveeventtogowiththistransmitevent.SimilartotheDCBscheme,anexternalcheckbacksystemappliedintheprogrammablelogicofyourpilotrelaycouldbeusedtoperiodicallycheckyourinputandoutputsbothlocallyandremotely.

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Spring–LukeWay115kvLineDCUB/TTRxSchemeDCUBSchemeshaveanormallyonGuardSignalfortransmitandreceive.TheTransferTripReceivershavegoodGuardSignalsaswell.

Figure26-SpectralAnalysisSpring–LukeWay115kvLine

ThisspectralanalysisinFigure26capturesthecompletepicture.ItshowusthecompleteDCUBsystemandthetwoTransferTriprecivers.Theselevelscanbearchivedandusedforfutureschemeevaluations.

ControlHouseConclusion

Fromactualeventstocheckbacktests,theschemescanbedeterminedtohaveoperatedcorrectly.Theinputsandoutputsarevalidated.Thespectralanalysesshowthecarriersetisshiftingandreturningtonormal.Levelsarecapturedandarchived.Ifdataisgatheredandmaintained,someofyourrelayandradiomaintenancecanbeavoided.

TheChannel

Spring–KingSt115kvLineDCBSchemeSomeofthebasicreadingsandinitialvaluesweregatheredfromourControlHousereadings.Tocompleteourchecksofthepilotsysteminvolvestakingreflectedpowerreadings.Inthepast,wesubmittedworkrequeststodisabletheschemestoinsertourtestequipmenttotakeareading.NowwesimplyremoteintothePCMandtakeactualin-servicereadings.ADCBschemeisnormallyoffanditmustbekeyedtotakeareflected

1 2 34

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powerreading.ThePCMcankeytheradiobypulsingitsoutput.Itthencancaptureareflectivepowerreading.

Figure27-In-servicereadings

Figure28-“AsLeft”ReadingsfromPastTesting

Asyoucanseefromtheabovereadings,thePCMcantakeanin-servicereadingthatcanbecomparedtoapast“AsLeft”reading.If,forexample,thereflectedpowerchangesbyonlyapercentortwo,itcanbeconcludedthatnothingsignificanthaschangedonyourline,inyourtuner,orwithyourlinetrap.IfyourinitialequipmentcalibrationsaredocumentedcorrectlyandthePCMisutilized,yourmaintenancefortheabovecanbeconsideredmuteandunnecessary.

PeriodicMaintenanceConclusion

TakingreadingsfromaPCMtakesamomentcomparedtothetypicalprocessofanengineerwithatestset.Onesuchmaintenanceintervalforasinglepilotschemecansaveyourcompanythousandsofdollars.

So,inconclusion,aPowerLineCarrierMaintenancedevice,ifproperlyinstalledandmaintained,cansignificantlyreducemaintenancecostsandschemedowntimes.Operationsonyoursystemwillbeeasilyidentifiableandinvestigated.Proper“AsLeft”datacanbeusedonanyequipmenttroubletohelpdocumentandtrendequipmentissues.PropertrendingwithyourspectralanalysiscouldhelputilitiesidentifyPLCissuesthatareathecauseforsystemincorrectoperations.TheusesofaPCMwillbeonlylimitedbyyourimagination.

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PCMApplicationtrialatSouthernCaliforniaEdisonforTroubleShootingPLC

Overview:

SouthernCaliforniaEdison’s(SCE)TechnicalSupportandStrategy(TS&S)grouphasperformedacostbenefitanalysisofpermanentlyinstallingPCM’sasameansofreducingthecostsnormallyassociatedwiththemaintenance,operationandtroubleshootingofourPowerLineCarrier(PLC)schemes.SCEhasdeterminedthatthecostsrelatedwithmaintainingandtroubleshootingtheirPLCschemeshavebeenincreasing,largelyduetotheattritionrateofqualifiedtechnicianswhohavethenecessarybackgroundandexperiencerequiredtoworkonPLCsystems.They’vealsodeterminedthatwhentheirhigh-speedPLCprotectionsystemsareoutofservice,especiallyforextendedperiodsoftime,thereareincreasedrisksofclearingfaultswiththeback-upprotectionsystems.

SCErecentlyappliedaPCMtooneofitsPLCsystems,toexplorewaystobegintoreducethecostsofmaintainingitsPLCsystems,andtoprovidecontinuousmonitoringofthehealthofitsPLCsystems.TheywereintriguedbytheabilityofaPCMtoprovideapassive,non-evasive,methodofcapturingthecarriersignal’sspectraldata.Further,theywantedtoevaluateifapplyingaPCMwouldallowthemtoconsidertheirPLCsystemstofully-monitored,asameansofextendingthemaintenanceintervalsfortheirPLCsystems.

EvaluationofaPCM:

SCE’sTechnicalSupportandStrategygroupfirstevaluatedthesetupandoperationofaPCMintheirlaboratory,locatedinPomona,CA.WhiletheycoulddemonstratesomeofthebasicfunctionalityofaPCMintheirlaboratory,itsoonbecameapparentthattheirlaboratoryenvironmentdidnotcontainallthenecessary,realworldcomponentsofatruePLCsystem(linetuners,linetraps,transformerhybrids,skewedhybrids,etc.).Theysoondeterminedthatitwastimetotakethenextstep,andapplyaPCMononeoftheirPLCsystems.TheyalsofeltthatevenmoreidealwouldbetoapplyaPCMtooneoftheirPLCsystemsthathadahistoryofreliabilityissues.

Asluck,wouldhaveit,SCE’sSubstationTestgrouphadbeenhavingissuesintroubleshootingapowerlinecarrierdirecttransfertrip(PLC-DTT)protectionsystemappliedtoitsAntelope–Whirlwind500kVtransmissionline.RefertoFigure29forthePLCconnections.ThePLC-DTTsystemhadbeenproducingspuriousTripReceivedsignalsfromoneofitstwotransmitter-receiversets.ThesespuriousTripReceivedsignalswerebeingreceivedatjustoneofthelineterminals,specificallyatAntelope.Unfortunately,therehavebeencaseswhenthisPLC-DTTsystemhasincorrectlyoperated,trippingopentheAntelope–Whirlwind500kVlineatbothends,whenspuriousTripReceivedsignalswerereceivedatAntelopefrombothofthisPLC-DTT’receiver.

Interestingly,ineachcasewhenthespuriousTripReceivedsignalshadbeenreceivedatAntelope,therewerenoindicationsofthecorrespondingTripSentsignalbeingsentfromtheoppositeWhirlwindlineterminal.ThisspuriousTripReceivedsignalissuehadbeengoingonforwellovertwo(2)years,andduringthattime,manydifferentTestcrewshadspenttimeonsite,troubleshootingthisissue.ThisspuriousTripReceivedsignalatAntelopehasresultedinthisPLC-DTTbeingremovedfromserviceforovertwoyears,now.Fortunately,inaccordancewithSCE’sstandards,there’saseconddirecttransfertripsystemappliedtothissame500kVtransmissionline,whichutilizesdigital

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Figure29-SCE’sAntelope-Whirlwind500kVPLC-DTTSystemConnections

microwavecommunications,commonlyreferredtoasMW-DTTatSCE.Thus,eventhoughthis500kVline’sPLC-DTTsystemhasbeenout-of-serviceformorethantwoyears,thissameline’sMW-DTTsystemhasremainedin-service,providingthedirecttransfertripcapabilitiesforthisline.

Asalast-ditcheffort,SCEsentthetransmitter/receiverunitsfromthisAntelope–Whirlwind500kV’sPLC-DTTsystembacktothevendor,withthehopesthattheycouldfindsometypeofissuewiththeirtransmitter/receiverunits.Unfortunately,theyfoundnoissueswiththesetransmitter/receiverunits,andtheyreturnedtheseunitsbacktoSCE.ThisAntelope-Whirlwind500kVPLC-DTTsystemhasbeenout-of-serviceforovertwoyears

Consideringtheabove,SCE’sTS&SgroupfeltthatthisAntelope–Whirlwind500kVPLC-DTTsystemwouldbeanidealcandidatetoevaluateaPCM.TheunreliabilityofthisPLC-DTTsystemhascostSCEmanyman-hoursoftroubleshooting,operationsswitchingcost,andthelossofoneoftheprotectionschemesonanin-service500kVtransmissionline.ItwasfeltthatapplyingaPCMtothisPLC-DTTsystemwouldprovidebenefitsbecauseofthereal-timedatacapture,andmightevenhelpSCE’sTestcrewstoresolvetheunreliabilityissueswiththisPLC-DTTsystem.

PilotApplicationofaPCM:

Inearly2016,SCE’sTS&SgroupbegantheirpilotevaluationofaPCM,astheyworkedtogetherwithfieldTestcrewstoinstallaPCMateachendoftheAntelope–Whirlwind500kVline’sPLC-DTTsystem.Figure29showsthatatbothAntelopeandWhirlwind,aPCMwasinstalledinserieswiththetri-axialcableconnectedbetweenthehybridcombinerunitandthelinetuner.

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LookingbackattheeventrecordsfromthisPLC-DTTsystem,itsoonbecameapparentthattherewasnoparticulartimeofdaythattheTripReceivedsignalswerebeingreceivedatAntelope.InordertoprovideanaccuratetimestampofthedatatoberecordedbythesePCM’s,aGPSreceiver’sIRIG-BtimesynchronizationwasconnectedtoeachPCM.

ItwashopedthatthePCMswouldprovidetheabilitytoobservesomeofcharacteristicsofthepowerlinecarriersignal,suchastransmittedpower,receivedpower,andreflectedpower.OncethesePCMswereinstalledandpoweredup,itwasnotedthatthesetheythecapabilitytomonitorthesethree(3)characteristicsofapowerlinecarriersignal,alongwithmanyothercharacteristics(refertoFigure27).

Capturingthesepowerlinecharacteristicsovertimeallowsdetailedanalysistobeperformed,whichmayhelptodeterminethecauseoferroneoustripswhichoccurduetospuriousnoise,intermittentlossofsignal,etc.Further,theabilitytostorethesepowerlinecharacteristics,astheyoccurovera24-hourtimeperiodthroughouttheyear,canbeveryhelpfulintheefforttomaintainthereliabilityofthesepowerlinecarriersystems.

DataCollectionandAnalysis:

SCE’sTS&SgrouphasbeentakingadvantageofthestoragecapabilitiesofthesePCMs,inorder,tocaptureeventrecordsstoredwithinthesetwo(2)PCM’s.

"ID","Date","Time","FFT","Channel","Description""20","04/15/2016","16:46:27:267","0","0","RFVoltageinRange""19","04/15/2016","16:46:26:519","0","0","RFVoltageOverload""18","04/15/2016","16:44:58:887","0","0","ConfigurationAccess""17","04/15/2016","16:44:58:615","0","0","AccountLoginadmin""16","04/15/2016","16:00:31:457","0","5","85-3FSKDTTRXLowFreq:GUARD""15","04/15/2016","16:00:30:783","1","5","85-3FSKDTTRXHiFreq:TRIP""14","04/15/2016","15:51:33:048","1","3","85-2FSKDTTRXHiFreq:GUARD""13","04/15/2016","15:51:32:349","0","3","85-2FSKDTTRXLowFreq:TRIP""12","04/15/2016","15:32:19:109","0","1","85-2FSKDTTTXReflectedOK""11","04/15/2016","15:32:18:900","0","5","85-3FSKDTTRXLowFreq:GUARD""10","04/15/2016","15:32:18:900","1","3","85-2FSKDTTRXHiFreq:GUARD""9","04/15/2016","15:27:46:509","1","1","85-2FSKDTTTXReflectedO/R""8","04/15/2016","15:27:46:309","1","5","85-3FSKDTTRXSignalO/R:Low""7","04/15/2016","15:27:46:309","1","3","85-2FSKDTTRXSignalO/R:Low""6","04/15/2016","13:09:46:452","0","0","TimedAccountLogoff:admin""5","04/15/2016","12:41:59:102","0","0","IRIG-BSynch""4","04/15/2016","12:40:31:709","0","0","ConfigurationChange""3","04/15/2016","12:40:30:239","1","3","85-2FSKDTTRXHiFreq:GUARD""2","04/15/2016","12:40:30:237","1","2","85-3FSKDTTTXLowFreq:GUARD""1","04/15/2016","12:38:56:021","0","0","IRIG-BUnsynch""0","04/15/2016","12:36:59:567","0","0","AuditLogCleared"

Figure30-ExampleEventRecordsofafromSCE’sAntelopeSubstation

TheeventrecordstypicallycapturedbyaPCM(Figure30)haveallowedtheend-usertoobservetime-taggedoperationalcharacteristicsoftheirrespectivePLCsystem,inthiscase,forSCE’sAntelope–Whirlwind500kVline’sPLC-DTTsystem.FortheAntelope–Whirlwind500kVline’sPLC-DTTsystembeingmonitoredbytwo(2)PCM’s,theresultshavebeenverytypicalforthirty-sixhundred(3,600)individualeventrecordstoberecordedoveraforty(40)dayperiod.

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InadditiontotheabilityofaPCMtocaptureandstorethesetypeofeventrecords,aPCMalsohasthecapabilitytocaptureandstoreFastFourierTransform(FFT)displaysofthepower-line-carriersignalbeingmonitored.Figure23,Figure24&Figure25showsomeexamplesofthesetypesofFFTdisplays,andthissetofthree(3)displaysshowstheshiftofoneofthetransmitterswithinSCE’sPLT-DTTsystemfromguardtoitsrespectivetripfrequency.

PreliminaryanalysisofboththeeventandFFTdatacapturedbythetwo(2)PCM’sinstalledonSCE’sAntelope–Whirlwind500kVline’sPLC-TTsystemhasshownaverydistinctpossibilityofflashoversoccurringacrossthedraincoil’ssparkgapsappliedonthisPLC-DTT’ssystem.ThedatacapturedbythesePCM’sshowanintermittentlossofguardsignaloccurringattheAntelopelineterminal.TheadditionoftheGPSreceiver’sIRIG-Bsignaltothesetwo(2)PCM’shasproventobeextremelyvaluable,sincetheseeventshavebeenshowntobeveryfrequentandunrelatedtoweather.FurtherdetailedanalysisoftheeventrecordsandFFTdisplaysfromthesePCM’shaveshownthatthelikelysourceoftheseeventsisaresultofpowerlinenoise,whichisaresultoftheswitchingofpower-factorcorrectioncapacitorbanksappliedtothesolarandwindpowergenerationinstallations,whichareinstalledveryclosetotheright-of-wayofSCE’sAntelope–Whirlwind500kVtransmissionline.

SCEispresentlyworkingtogetherwiththevendorofthetransmitter/receiverequipmentappliedtoitsAntelope–Whirlwind500kVline’sPLC-DTTsystem,toexplorewaystomodifysomeoftheoperatingcharacteristicsoftheirtransmitter/receiverunits,tomakethisPLC-DTTsystemmoreresilienttotheabovesourcesofpowerlinenoise.ThedecisiontoinstallaPCMatbothendsoftheirAntelope–Whirlwind500kVline’sPLC-DTTsystemhasprovidedSCE’sTS&SgroupwiththetechnicaldatatheyneededtodeterminethecausebehindthereliabilityissuestheyhadbeenhavingwiththisPLC-DTTsystem.

CONCLUSIONSAPCMtypedeviceprovidestheuseranewtooltomonitor,maintainandtroubleshootapower-line-carriersystemusedforsystemprotection.ThecombinationofextendingmaintenancecyclesandmonitoringthesystemforunexpectedchangestypicallyrecoversthecostofthedeviceinarelativelyshorttimeandhelpstheuserbettercomplywithNERCstandardPRC-005-002[4].Theeventlogs/alarms,trendingandeventdrivenspectralanalysisprovidelongtermmonitoringofthesystemforyearsandameansforavoidingand/orevaluatingmisoperationsthatmayoccurinthefuture.Thisindependentmonitoringdeviceprovidestheuseraddedconfidencethatvaluableinformationwillbeavailable(withouttheneedforlineoutages)whenneededtoprovidedirectiontoapossiblesolutionandcauseoftheproblem.

REFERENCES1) IEEEStd643-2004,“IEEEGuideforPower-LineCarrierApplications”,2005

2) MiriamSanders&RogerRay,“Power Line Carrier Channel & Application Considerations For Transmission Line Relaying”, Ametek Power Publication #C045-P0597, 1997

3) IEEEPSRCWorkingGroupReport,“RedundancyinCouplingPowerLineCarrierChannelstothePowerLine”,WG15,2011

4) NERCStandard,PRC-00502,“ProtectionSystemMaintenance”

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AUTHORBIOGRAPHY’SRobertBaldwin

RobertreceivedaB.S.E.E.fromCaliforniaStateUniversity,LongBeachin1982,andanM.S.E.E.fromCaliforniaStateUniversity,LosAngelesin2007.He’sspentover32yearsatSouthernCaliforniaEdison(SCE),holdingpositionsofSubstationElectrician,TestTechnician,ShopEngineer,ProtectionEngineer,OperationsTrainer,TestSchoolSupervisor,andmostrecently.SeniorTechnicalSpecialistintheirRelay/Testgroup.DuringhistenureatSCE,hisprimaryfocushasbeenwiththeapplication,settingandtestingofprotectiverelays,powerlinecarriersystems,anddigitalfaultrecorders.RobertisapastChairoftheGeorgiaTechTransientRecorderUser’sCouncil.

JeffreyBrown

Graduated1997withaBachelorofScienceinEngineeringfromGeorgiaTechUniversity.Aftergraduation,heworkedforGeorgiaPowerfor25yearsandfinishedasTeamLeaderforPowerLineCarriercoveringtheStateofGeorgia.HepresentlyworksforGeorgiaTransmissionCorporationasPrincipalEngineerTransmissionandPowerLineCarrierSupport.HeistheauthorofPowerLineCarriers:Simplified.

RayFella

RayreceivedhisBachelorofScienceinElectricalEngineeringin1987fromRutgersUniversityinNewBrunswick,NJ.Hehasspenthis30-yearcareersupportingtheElectricUtilitySystemProtectionCommunicationsindustry.In2001,hejoinedPowerCommSolutions,LLCasBusinessDevelopmentDirectorwherehereceivedhisfirstpatent.PriortoPowerCommSolutions,heworkedforSignalcraftersandstartedhiscareerwithINIVEN.Heisa28yearmemberofIEEE,amemberofthePowerandEngineeringSociety,aswellasnumberofworkinggroups.

AlanJayson

Alanhasspentthelast31yearsdesigningvariousaudiotoneandpowerlinecarriercommunicationandinstrumentationproductsfortheElectricUtilitysystemprotectionindustry.Hestartedhiscareerin1986withINIVEN,wherehelpeddesignprotectioncommunicationsystemsthatarestillinusetoday.In2012hejoinedPowerCommSolutionsasleaddesignengineerandpriortothatworkedforSignalcraftersfor14years.Heisalsoapatentholder.

RogerRay

RogerreceivedaBSinElectricalEngineeringatthePennsylvaniaStateUniversityin1964andanMSdegreeattheNewJerseyInstituteofTechnologyin1976.

HeisamemberoftheIEEEandamemberofthePower&EnergySocietyandtheCommunicationsTechnologySociety.HeispastChairmanof(whatwasthen)theIEEEPowerSystemCommunicationsCommitteeandispresentlyChairmanofthePowerLineCarrierSubcommitteeofthePSCC.HeisalsoamemberofthePowerSystemRelaying&ControlCommittee.Intheyear2000,hewasalsoelectedasaFellowintheIEEE.

HeisanauthoroftwochaptersintheWestinghouseAppliedProtectiveRelayingBook.Heauthoredseveralpapersinhismajorfieldsofpilotrelaysystemsandpowersystemcommunications.ThesepapershavebeenpresentedatmajorrelayconferencesaroundthecountryaswellasconferencesoutsidetheUS.He,alongwithco-authorShanSun,receivedtheIEEEPowerEngineeringSocietyPrizePaperAwardfor1983andheholdsfivepatentsintheUSonsubjectscoveringphasecomparisonrelaying,powerlinecarrier,andfiberoptics.

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NeilStone

NeilreceivedhisBSEE-ITTTechnicalInstitute,SanDiego1998andPMPCertification–UniversityOfIrvineCa,2010.HeisalsoanIEEEMember.Neil’sworkexperienceincludesthefollowing:SonyCorp,applicationsengineer,RFCDMAdeploymentwithQualcomm(3years),PentadynePower,applicationsengineer,commercialflywheelUPSsystems(4years),ABB-PowerOne,fieldengineer,commissioncommercialUPSsystems(4years),SouthernCaliforniaEdison–NuclearTest(3years),NuclearStartupEngineer(2years),NuclearMaintenanceGeneralForeman(3years),SouthernCaliforniaEdison–TechnicalSpecialist/ScientistforTransmission&Distribution,StartupEngineer(3years)andiscurrentlyworkingwithSouthernCaliforniaEdisonasTechnicalManagerforTransmission&Distribution,RelayTestandTechnicalSupport(2years).