国际标准的发展促进国内PLC的研究.docx

国际标准的发展促进国内PLC的研究.docx

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国际标准的发展促进国内PLC的研究

PLCStudiesinChinaasaContributiontotheDevelopmentofInternationalStandards

Abstract

InthefieldofPLC,thestandardizationprocessoninternationallevelisprogressingveryslowly.TheEMCLaboratoryoftheNorthChinaElectricPowerUniversityhasreceivedthetasktodevelopameasurementmethodforthefieldradiatedbyPLCinstallationsandastandardtobeusedinthefuturefortheregulationofthePLCdeployment.Afterashortintroductionofthestandardizationprocessatinternationallevel,thepaperpresentsmeasurementsperformedattheNorthChinaElectricPowerUniversityofradiatedfieldsduetoPLC.Comparisonsofthefieldwithvariouslimitsareshown.Finallythepaperalsopresentsareviewoftheregulatorysituationoninternationallevel.

Keywords:

PLC,standardization,electromagneticdisturbances.

1.Introduction

Inthelast6to7years,feasibilitystudieshavebeenperformedinvariouscountriestocheckthepossibilityofusingthelowvoltagedistributionnetworktoprovidedatatransmissionandeventuallyalsotelephoniclinkstoindividualcustomersatfrequenciesupto30MHz.ThisnewtechnologyiscalledPowerLineCommunication（PLC）.Thisapplicationisparticularlyinterestingforpowerutilitieswhich,ononesidecanenterinthiswaythetelecommunicationmarketandusetheirnetworkforpowernetworkdatatransmission,ontheothersidecanusethistechnologytocontroltheirownnetwork.

However,thistransmissionmodeinthefrequencybandextendingfrom1.6to30MHzpresentsvariousandquitecomplexEMCproblems.Themainproblemisproductionofdisturbancesinthenetworkandintheenvironment.

2.Disturbancesources

Thesourcesofdisturbancearebothradiatedandconducted:

-theemissionofelectromagneticnoisewhichcaninterferewithradiocommunicationsforsafetyormilitaryuse,ordisturbtheradioamateurs;

-conducteddifferentialandcommonmodecurrentscanpenetrateinanyequipmentconnectedtothenetworkinwhichPLCisworking.Thedisturbanceshavetwotypesoforigins:

-thesignalsourceasymmetry,duetothecouplerasymmetry;

-theunbalanceoftheLowVoltageDistributionNetwork（LVDN）andasaresultancommonmodetodifferentialmodeconversion.

Theconversionfromdifferentialtocommonmodeduetothenetwork

unbalancehasbeenanalysedinvariouspaper,asforinstancein[1].Differentmitigationsolutionshavebeenalsobeenproposedintheliterature[2,3,4],buttheresearchworkmustbefurthercontinued.

3.Standardizationatinternationallevel

ConcerningEMCproblems,ataninternationallevel,twotypesofstandardsmustbedeveloped:

-aproductstandard;

-anetworkstandard.

3.1Theproductstandard

TheproductstandardshouldbeanamendmentoftheCISPR22standardandisthetaskoftheSubcommitteeCISPR/I/.

AfirstideawastoextendtheconceptofLongitudinalConversionLoss（LCL）specificforsymmetrictelecommunicationpairsofwiretothenonsymmetricpowernetwork.

Measurementsperformedinvariouspowernetworks,asthoseshowninFig.1,havegivenalargespreadofLCLvalues[5].

ItwasnotpossibletoarrivetoaconsensusfortheconceptbasedontheLCLvalue,tobeusedforthecalculationofavoltagelimitattheportsoftheequipmentconnectedtothenetwork,althoughthatthisconcepthasbeenwell-establishedforthecaseoftelecommunicationlines.Afterabout4yearsofworkandawholeseriesofdocumentsatCD（CommitteeDraft）stage,theconceptdidnotfindtherequestedqualifiedmajorityforapprovalbytheCISPR/I/althoughthatitfoundmajorityapprovalwithintheworkinggroup.Itwasdecidedtore-starttheworkevaluatinganewbasis.

ANewWorkItemProposal（NWIP）waspreparedbytheFrenchnationalCommitteeandapprovedinApril2005[6].TheworkwillnotbefocusedanymoreontheLCLvalue,butwilltryto:

-describethetypicalelectricityinstallationswhereitisintendedtoconnectPLCequipment;

-identifythepotentiallydisturbedservices/equipmentforeachtypicalsectionofelectricityinstallationsdescribedabove;

-assessthelevelofprotectioncurrentlyprovidedbytheCISPR22

foreachequipment/service;

-setradiatedandconductedlimitsforemissionsofeachtypicalsectionofelectricityinstallationwhenPLCisoperating.

TheworkstartedinJune2005andiscurrentlyinprogress.

3.2Networkstandard

TheEuropeanCommissionhasissuedin2001theMandate313whichgivesCENELECandETSIthetasktodevelopastandard,todefineemissionlimitsforallcommunicationnetworksincludingPLC[7].

Differentlimitshavebeenproposedbyvariouscountries（Germany,UK,Norway）andentities（CENELEC,FCC,BBC）.Thedifferencesbetweenthevariousproposalswerequitelargeanditwasnotpossibletoreachaconsensus.

AJointWorkingGroupETSI/CENELEChasproducedseveraldrafts,w