PowerSystemsEngineeringCenter

Preven&onofUninten&onalIslandsinPowerSystemswithDistributedResources

BenKroposkiNa3onalRenewableEnergyLaboratory

August2016

2

Presenta3onOutline

•  TypesofislandsinpowersystemswithDR

•  Issueswithuninten3onalislands•  Methodsofprotec3ngagainstuninten3onalislands

•  Standardtes3ngforuninten3onalislanding•  Advancedtes3ngofinvertersforan3-islandingfunc3onality

•  Probabilityofuninten3onalislanding•  Thefutureofan3-islandingprotec3on•  References

3

•  AreaEPS–AreaElectricPowerSystem•  LocalEPS–LocalElectricPowerSystem•  PCC–PointofCommonCoupling•  DR–DistributedResource(e.g.distributedgenera3on

(DG),distributedenergyresource(DER))•  DER–DistributedEnergyResource(TheIEEE1547Working

GroupvotedanddecidedtochangeDRtoDERinthenextversion.DERwillNOTincludeDemandResponseasitdoesinsomecountries)

•  An&-islanding(non-islandingprotec3on)–Theuseofrelaysorcontrolstopreventthecon3nuedexistenceofanuninten3onalisland

Terms

4

Island:Acondi3oninwhichapor3onofanAreaEPSisenergizedsolelybyoneormoreLocalEPSsthroughtheassociatedPCCswhilethatpor3onoftheAreaEPSiselectricallyseparatedfromtherestoftheAreaEPS.[1]

•  Inten3onal(Planned)•  Uninten3onal

(unplanned)

IslandDefini3on

DR

115kV

13.2kV

AdjacentFeeder

Islandformswhenbreakeropens

5

Inten3onalIslands(Microgrids)

IEEE1547.4isaguideforDesign,Opera3on,andIntegra3onofInten3onalIslands(e.g.Microgrids)[3]

(1)haveDRandload(2)havetheabilitytodisconnectfromandparallelwiththeareaEPS(3)includethelocalEPSandmayincludepor3onsoftheareaEPS,and(4)areinten3onallyplanned.

IEEE2030.7and2030.8–Indevelopmentandcovermicrogridcontroldesignandtes3ng

Distribution Feeder from Substation

Open for a Utility

Microgrid

DSDG Load Load

DG Load

MicrogridSwitch

Distributed Generation

Distributed Generation

Distributed Storage

Open for a Facility Microgrid

PossibleControl Systems

MicrogridSwitch

Source:Makingmicrogridswork[2]

6

•  PersonnelSafety–Uninten3onalislandscancausehazardsforu3lityworkersiftheyassumedownedlinesarenotenergizedduringrestora3on

•  Overvoltages–Transientovervoltagesduetorapidlossofloadarepossible.Ifanadequategroundsourceisnotpresentintheisland,agroundfaultcanresultinvoltagesthatexceed173%ontheunfaultedphases.

•  Reconnec&onoutofphase-ThiscanresultinlargetransienttorquesappliedtomotorsconnectedtotheislandedareaEPSandtheirmechanicalsystems(e.g.,shacs,blowers,andpumps),whichcouldresultindamageorfailure.

•  PowerQuality–UnplannedislandareaEPSmaynothavesuitablepowerqualityforloads

•  Protec&on–Uninten3onalislandsmaynotprovidesufficientfaultcurrenttooperatefusesorovercurrentrelayprotec3ondevicesinsideisland

IssueswithUninten3onalIslanding

References[4]-[7]

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•  Synchronousgeneratorsarevoltagesourcedevicesthatcansupportislandedgridopera3ons.Synchronousgeneratorsaretypicalindieselornaturalgaspoweredengine-generators.

•  Induc&ongeneratorsusuallywillnotbeabletosupportanislandbutwillinsteadceasetoproducecurrentbecauseofthelossofreac3vepower,whichisnecessarytosupportarota3ngmagne3cfieldwithinthegenerator.Ifsufficientcapaci3vereactanceisavailabletosupplythereac3vepowerrequirementsoftheinduc3ongeneratorfield,eitherthroughtheinstalla3onofpowerfactorcorrec3oncapacitorsorthepresenceofconsiderablecable-typepowerconductors,itmaybenecessarytoprovidefordirectdetec3onoffaultsinamannersimilartothatofsynchronousgenerators.[4]Induc3ongeneratorsarefoundinsomeengine-gensetsandwindturbines.

•  Inverter-BasedDRaretypicallycurrent-sourcedevicesthatrequireavoltage-source(typicallytheu3litygrid)tosynchronizeto.Voltage-source(e.g.gridforming)invertersdohavetheabilitytosupportislandedopera3on.InvertersarefoundinPVsystems,windturbines,microturbines,fuelcells,andbaeeryenergystorage.

UnderstandingDRSources

References[4]

8

IEEE1547:Uninten3onalIslandingRequirement

Foranuninten3onalislandinwhichtheDRenergizesapor3onoftheAreaEPSthroughthePCC,theDRinterconnec3onsystemshalldetecttheislandandceasetoenergizetheAreaEPSwithintwosecondsoftheforma3onofanisland.[1]

IEEE1547-2003:4.4.1Uninten&onalIslandingRequirement

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IEEE929[8]–EarlyPVInterconnec&onStandardthathasbeenreplacedbyIEEE1547•  Definednonislandinginverterasaninverterthatwillceasetoenergizetheu3litylineinten

cyclesorlesswhensubjectedtoatypicalislandedloadinwhicheitherofthefollowingistrue:

a)Thereisatleasta50%mismatchinrealpowerloadtoinverteroutput(thatis,realpowerloadis<50%or>150%ofinverterpoweroutput).b)Theislanded-loadpowerfactoris<0.95(leadorlag).

•  Ifthereal-power-genera3on-to-loadmatchiswithin50%andtheislanded-loadpowerfactoris>0.95,thenanonislandinginverterwillceasetoenergizetheu3litylinewithin2swhenevertheconnectedlinehasaqualityfactorof2.5orless.

IEEE1547-2003(EarlyDraYs)•  DraY5–2secondtodetectandceasetoenergize•  DRAFT6/7-Foranuninten3onalislandinwhichtheDRandapor3onoftheArea

EPSremainenergizedthroughthePCC,theDRshallceasetoenergizetheAreaEPSwithintensecondsoftheforma3onofanisland.Tensecondswasrecommendedbysynchronousgeneratormanufacturesasareasonablevalue.

•  DraY8andbeyond–changeduninten3onalislandingrequirementto2secondstogetclosertoinstantaneousrecloserseings.InverterswerealreadyseenascapablefromIEEE929requirement.

Uninten3onalIslandingRequirementBackground

10

IEEE1547-2003:Uninten3onalIslandingRequirement

FootnotetoIEEE1547Requirement[1]Someexamplesbywhichthisrequirementmaybemetare:•  TheDRaggregatecapacityislessthanone-thirdoftheminimumloadoftheLocalEPS.

•  TheDRinstalla3oncontainsreverseorminimumpowerflowprotec3on,sensedbetweenthePointofDRConnec3onandthePCC,whichwilldisconnectorisolatetheDRifpowerflowfromtheAreaEPStotheLocalEPSreversesorfallsbelowasetthreshold.

•  TheDRiscer3fiedtopassanapplicablenon-islandingtest.•  TheDRcontainsothernon-islandingmeans,suchasa)forcedfrequencyorvoltageshicing,b)transfertrip,orc)governorandexcita3oncontrolsthatmaintainconstantpowerandconstantpowerfactor.

11

TheDRaggregatecapacityislessthanone-thirdoftheminimumloadoftheLocalEPS.

•  IftheaggregateDRcapacityislessthanone-thirdofthelocalEPSload,itisgenerallyagreedthat,shouldanuninten3onalislandform,theDRwillbeunabletocon3nuetoenergizetheloadconnectedwithinthelocalEPSandmaintainacceptablevoltageandfrequency.[4]

•  Theoriginofthis3-to-1load-to-genera3onfactorisanIEEEpaper[9]basedonsimula3onsandfieldtestsofinduc3onandsynchronousgenera3onislandedwithvariousamountsofpowerfactor-correc3ngcapaci3vekilovoltamperesreac3ve.

•  Itwasshownthatasthepre-islandloadingapproachedthree3mesthegenera3on,noexcita3oncondi3oncouldexisttosupportthecon3nuedpowergenera3on.

DRAggregateCapacity

12

Methodsofprotec3ngagainstuninten3onalislands

•  Reverse/MinimumImport/ExportRelays•  PassiveAn3-islanding•  Ac3veAn3-islanding

o  e.g.instabilityinducedvoltageorfrequencydricand/orsystemimpedancemeasurementcoupledwithrelayfunc3ons

•  Communica3on-BasedAn3-Islandingo  Directtransfertrip(DTT)o  Powerlinecarrier(PLC)o  ImpedanceInser3on

•  MethodsUnderDevelopmento  Phasor-basedan3-islanding

References[10]-[37]

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•  Protec3veRelayFunc3on(ReversePower=32)

•  UsedincaseswheretheDRisnotexpor3ngtothegrid

•  LocalloadsaretypicallylargerthanDR

Reverse/MinimumImport/ExportRelays

DR

115kV

13.2kV

AdjacentFeeder

81O/U

59 27 32

14

•  Over/undervoltageandfrequencytripseings

•  Voltageandfrequencyrelayfunc3ons(81o,81u,27,59)

•  SetaV/Fwindow–ifcondi3onsareoutsidewindow,thenDRtrips

•  Non-detectzone(NDZ)existsbetweentrippoints

•  Amendment1(IEEE1547a)allowsforadjustableclearing3mes

PassiveAn3-islanding

NewVoltageandFrequencyTripsSeingsfromAmendment1ofIEEE1547-2003[38]

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•  Rate-of-change-of-frequency(ROCOF)

•  VoltageorCurrentHarmonicMonitoring–monitorvoltageharmonicdistor3on

•  VoltagePhasejump-detectasudden“jump”inphasedisplacementbetweeninvertervoltageandoutputcurrent

OtherPassiveAn3-islanding

VoltagePhaseJump[15]

16

•  ImpedanceMeasurement•  Detec3onofImpedanceat

aSpecificFrequency•  Slip-modeFrequencyShic•  FrequencyBias•  SandiaFrequencyShic•  SandiaVoltageShic•  FrequencyJump•  ENSorMSD(adeviceusing

mul3plemethods)

Ac3veAn3-islanding

Ac3vemethodsgenerallyaeempttodetectalossingridbyac3velytryingtochangingthevoltageand/orfrequencyofthegrid,andthendetec3ngwhetherornotthegridchanged.

17

•  PowerLineCarrier–Provideapermissiverunsignal,whensignalgoesaway,theDRceasestoenergizecircuit

•  ImpedanceInser3on–RemotelyaddcapacitorsthatcausealargeenoughvoltagechangetotripO/Uvoltageprotec3on

•  DTT–nextslide

Communica3ons-basedMethods

18

•  DirectTransferTrip(DTT)providesacommunica3onssignalfromtheAreaelectricpowersystemcomponentsuchasafeederbreakerorautoma3clinesec3onalizingdevicestotheDRortheaddi3onofsync-checkrelayingorundervoltage-permissiverelayingatthefeederbreakerorautoma3clinesec3onalizingdevices.[4]

•  DTTschemeisusedtoavoidaccidentalparallelingoflargerDRtothegrid.

•  DTTmayrequirecommunica3onsnotonlyfromthesubsta3onbreakerbutalsofromanyautoma3clinesec3onalizingdevicesupstreamfromtheDR.

DirectTransferTrip(DTT)

•  ExamplesofDTT(fromPG&Einterconnec3onrequirements[39]:o  DirectFibertoSubsta3onwithproperinterfaceprovisioningo  LicensedMicrowavewithproperinterfaceprovisioningo  ClassADS04-WireLeaseLineprovisionsbyLocalExchangeCarrier(LEC)o  addi3onalDirectTransferTrip(DTT)Telecommunica3onOp3onsviathenewClassB,T1

LeaseOp3ons•  Drawback:DTTocenusesadedicatedfiberorothercommunica3ons

infrastructurewhichiscostlytoinstallandoperate.

AllFiberDTTProtec3onCircuit[39]

19

•  Phasor-basedan3-islanding[31]

Methodsunderdevelopment

PhasorswhenGrid-connected

PhasorswhenIslanded

20

StandardUninten&onalIslandingTes&ng

21

•  IEEE1547.1detailstes3ngrequirementsforuninten3onalislanding[40]

•  UsesamatchedRLCloadandmeasurestrip3meswhenislandcondi3onoccurs

•  TheRLCloadissettoaQualityfactor(Qf)=1.0

•  Qfof1.0isequivalenttoaloaddisplacementpowerfactorof0.707.

•  Distribu3oncircuitstypicallyoperateatavaluegreaterthan0.75p.f.

•  Conductedat100%,66%,and33%ratedpower

•  Thetestistoberepeatedwiththereac3veload(eithercapaci3veorinduc3ve)adjustedin1%incrementsoralterna3velywiththereac3vepoweroutputoftheEUTadjustedin1%incrementsfrom95%to105%oftheini3albalancedloadcomponentvalue.Ifunitshutdown3mesares3llincreasingatthe95%or105%points,addi3onal1%incrementsshallbetakenun3ltrip3mesbegindecreasing.

IEEE1547.1–Uninten3onalIslandingTest

Figure2—Uninten3onalislandingtestconfigura3onfromIEEE1547.1

•  AQfof2.5wasusedinIEEE929-2000andisequivalenttoaloaddisplacementpowerfactorof0.37.[8]

•  Qfwasreducedto1.0duringevalua3onofIEEE1547.1toreducetes3ngburdensincerunon3meswerenotsignificantlylongerat2.5

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•  Loadismatchedinrealandreac3vepower[40]

•  Testedat:o  MinimumLoadatunity1.0p.f.

o  Maximumrealloadatunity1.0p.f.

o  Maximumrealloadatratedp.f.lagging

o  Maximumrealloadatratedp.f.leading

Uninten3onalIslandingTestforSynchronousGenerators

Figure3—Uninten3onalislandingtestforsynchronousgeneratorsconfigura3on

fromIEEE1547.1

23

•  Tomeettheuninten3onalislandingrequirementin1547,theDRinstalla3onmaycontainreverseorminimumimportpower-flowprotec3on[40]

•  SensedbetweenthepointofDRconnec3onandthePCC,itdisconnectsorisolatestheDRifpowerflowfromtheareaEPStothelocalEPSreversesorfallsbelowasetthreshold.

•  IEEE1547.1testsevaluatethemagnitudeand3meofthereverse/minimumpowerflowprotec3vedevice.

ReversePowerFlow(foruninten3onalislanding)

24

AdvancedTes&ng

25

EnergySystemsIntegra3onFacility(ESIF)

OfficesHPC-DCLaboratoriesUniqueCapabili3es•  Mul3pleparallelACandDCexperimental

busses(MWpowerlevel)withgridsimula3onandloads

•  Flexibleinterconnec3onpointsforelectricity,thermal,andfuels

•  Mediumvoltage(15kV)microgridtestbed

•  Virtualu3lityopera3onscenterandvisualiza3onrooms

•  Smartgridtes3nglabforadvancedcommunica3onsandcontrol

•  Interconnec3vitytoexternalfieldsitesfordatafeedsandmodelvalida3on

•  PetascaleHPCanddatamgmtsysteminshowcaseenergyefficientdatacenter

•  MW-scalePowerhardware-in-the-loop(PHIL)simula3oncapabilitytotestgridscenarioswithhighpenetra3onsofcleanenergytechnologies

Shortening the time between innovation

and practice

hep://www.nrel.gov/esif

26

EnergySystemsIntegra3onFacility(ESIF)

Smartbuildings&controllableloads

PowerSystemsIntegra&onGridSimulators-Microgrids

EnergySystemsIntegra&onFuelCells,Electrolyzers

OutdoorTestAreasEVs,Transformers,CapacitorBanks,VoltageRegulators

RooYopPV EnergyStorage-Residen3al,Community&GridScaleStorage

HPC&DataCenter

AdvancedDistribu&onManagement

Systems

hep://www.nrel.gov/esif/

27

•  PowerHardwareintheLoop(PHIL)–replicateloadsandsomegridcomponentofthetestinsimula3on

•  ThevariableRLCloadPHILapproachiseffec3veforachievingcondi3onsthataredifficulttoreplicatewithdiscretehardware[42][43]

•  Maynotworkonallac3veAImethods

AdvancedTes3ng-PHIL

28

•  SandiaTes3ng[44]–examined4inverters/singlePCC(demonstratedthatmul3pleinverterss3llmeet2secrequirement).

•  NRELTes3ngwithSolarCity&HECO[45]-examined1)theimpactsofbothgridsupportfunc3onsand2)mul3-inverter(3)/mul3PCCislandsonan3-islandingeffec3veness.o  Showedthatwithgridsupportfunc3ons(volt/varandfrequency/wae)enabled,the2secrequirementiss3llmet.

o  Showedthatmul3plePCCsdidnotcausetrip3mesbeyond2seconds(regardlessofsystemtopology)

o  Resultsonlyvalidoninverters/designsthatweretested

Mul3pleInverterTes3ng

29

ProbabilityofUninten&onalIslands

30

•  Tocreateanelectricalisland,therealandreac3vepowerflowsbetweenDRandloadsmustbeexactlymatched

•  Whatistheprobabilityofthishappening?

•  IEAPVPSTask5–Study[46]o  The“benchmark”riskthatalreadyexistsfornetworkoperatorsand

customersisoftheorderof10-6peryearforanindividualpersono  TheriskofelectricshockassociatedwithislandingofPVsystems

underworst-casePVpenetra3onscenariostobothnetworkoperatorsandcustomersistypically<10-9peryear

o  Thus,theaddi3onalriskpresentedbyislandingdoesnotmateriallyincreasetheriskthatalreadyexistsaslongastheriskismanagedproperly

o  Balancedcondi3onsoccurveryrarelyforlow,mediumandhighpenetra3onlevelsofPV-systems.

•  Theprobabilitythatbalancedcondi3onsarepresentinthepowernetworkandthatthepowernetworkisdisconnectedatthatexact3meisvirtuallyzero.[47][48]

ProbabilityofIslanding

31

SuggestedGuidelinesforAssessmentofDGUninten3onalIslandingRisk–SandiaReport[49]•  CasesinWhichUninten3onalIslandingcanbeRuledOut

o  AggregatedACra3ngofallDGwithinthepoten3alislandislessthansomefrac3onoftheminimumrealpowerloadwithinthepoten3alisland

o  Notpossibletobalancereac3vepowersupplyanddemandwithinthepoten3alisland.

o  DTT/PLCPisused•  CasesinWhichAddi3onalStudyMayBeConsidered

o  Poten3alislandcontainslargecapacitors,andistunedsuchthatthepowerfactorwithinapoten3alislandisverycloseto1.0

o  Verylargenumbersofinverterso  Invertersfromseveraldifferentmanufacturerso  Includebothinvertersandrota3nggenerators

GuidelinesforAssessmentofDGUninten3onalIslandingRisk

32

•  PassiveislandingocenhasaNDZ,butitishardforpowersystemstomaintainagenera3on/loadbalanceforextendedperiodsof3me(beyond10s)[50]

•  Ac3vean3-islandingtechniquesarefastandworkbeston“s3ff”grids.Mosttechniquesworkwhenasignificantchangeinsystemcharacteris3csoccurbecauseofislandforma3on.

•  Newintegra3onrequirementsareopeningupvoltageandfrequencytrippointstoenablegridstabilityathighDRpenetra3ons

•  Mul3plesofac3vean3-islandingtechniquesmayormaynotworkagainsteachother.

•  Futurepowersystemsmaynotbeass3ffwithreduceduseofsynchronousgenerators.

TheFutureofAn3-islandingProtec3on

33

•  2srequirement–Isthistherightnumber?o  Tooslowforinstantaneous/fastreclosingo  Toofastforsomecommunica3onsbasedAImethodso  Needac3veAItoachievethiswithmatchedload

•  Ac3veAn3-islanding–Isitneeded?o  WhathappenswhenyouhavethousandsofdifferenttechniquesanddeployedDR?

o  Shouldtherebe1methodthateveryonemustuse?(triedbefore,butpatentsgotintheway)

o  Willac3veAIworkagainstmaintaininggridstabilityathighpenetra3onlevels?

ItemsforDiscussion

34

[1]1547™-2003IEEEStandardforInterconnec3ngDistributedResourceswithElectricPowerSystems

[2]Kroposki,B.,Lasseter,R.,Ise,T.,Morozumi,S.Papathanassiou,S.,andHatziargyriou,N.,“Makingmicrogridswork”,IEEEPowerandEnergyMagazine,Vol.6,Issue3,pp.40-53,2008

[3]IEEE1547.4™-2011IEEEGuideforDesign,Opera3on,andIntegra3onofDistributedResourceIslandSystemswithElectricPowerSystems

[4]IEEE1547.2™-2008IEEEApplica3onGuideforIEEEStd1547™,IEEEStandardforInterconnec3ngDistributedResourceswithElectricPowerSystems

[5]Walling,R.,Miller,N.“DistributedGenera3onIslanding–Implica3onsonPowerSystemDynamicPerformance”,IEEEPowerEngineeringSocietySummerMee3ng,pp.92-96,2002

[6]Barker,P.,deMello,R.,“DeterminingtheImpactofDistributedGenera3ononPowerSystems:Part1–RadialDistribu3onSystem”,PowerengineeringSocietySummerMee3ng,pp.1645-1655,2000

[7]Stevens,J.,Bonn,R.,Ginn,J.,Gonzalez,S.,Kern,G.,“DevelopmentandTes3ngofanApproachtoAn3-islandinginU3lity-InterconnectedPhotovoltaicSystems”SandiaReportSAND-2000-1939,August2000

[8]IEEE929-2000IEEERecommendedPrac3ceforU3lityInterfaceofPhotovoltaic(PV)Systems

[9]Gish,W.B.,Greuel,S.,andFeero,W.E.,“Ferroresonanceandloadingrela3onshipsforDSGinstalla3ons,”IEEETransac3onsonPowerDelivery,Vol.PWRD-2,no.3,pp.953–959,July1987

[10]Kobayashi,H.Takigawa,K,Hashimoto,E.,Kitamura,A.,Matsuda,H.,“MethodforPreven3ngIslandingPhenomenoninU3lityGridwithaNumberofSmallScalePVSystems”,IEEEPhotovoltaicSpecialistsConference,pp.695-700,1991IEEE

References

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[11]Kobayashi,H.Takigawa,K.,“Sta3s3calEvalua3onofOp3mumIslandingPreven3ngMethodforU3lityInterac3veSmallScaleDispersedPVSystems”,FirstWorldConferenceandExhibi3ononPhotovoltaicSolarEnergyConversion,pp.1085-1088,1994

[12]Begovic,M.,Ropp,M.,Rohatgi,A.,Pregelj,A.,“DeterminingtheSufficiencyofStandardProtec3veRelayingforIslandingPreven3oninGrid-ConnectedPVSystems”,2ndWorldConferenceandExhibi3ononPhotovoltaicSolarEnergyConversion,pp.2519-2524,1998

[13]Ropp,M.,Begovic,M.,Rohatgi,A.,“AnalysisandPerformanceAssessmentoftheAc3veFrequencyDricMethodofIslandingPreven3on”,IEEETransac3onsonEnergyConversion,Vol.14,No.3,1999

[14]Ropp,M.,Aaker,K.,Haigh,J.,Sabbah,N.“UsingPowerLineCarrierCommunica3onstoPreventIslanding”,IEEEPhotovoltaicSpecialistConference,pp.1675-1678,2000

[15]Bower,W.,Ropp,M.,“Evalua3onofIslandingDetec3onMethodsforU3lity-Interac3veInvertersinPhotovoltaicSystems”,SandiaReportSAND-2002-3591,2002

[16]Ye,Z.,Kolwalker,A.,Zhang,Y.,Du,P.,Walling,R.,“Evalua3onofAn3-IslandingSchemesBasedonNondetec3onZoneConcept”,IEEETransac3onsonPowerElectronics,Vol.19,No.5,September2004

[17]Ye,Z.,Walling,R.,Garces,L.,Zhou,R.,Li,L.,Wang,T.,“StudyandDevelopmentofAn3-islandingControlforGrid-ConnectedInverters”,NRELReportNREL/SR-560-36243,May2004

[18]Yin,J.,Chang,L.,Diduch,C.,“ANewAdap3veLogicPhase-ShicAlgorithmforAn3-islandingProtec3oninInverter-BasedDGSystems”,IEEE36thPowerElectronicsSpecialistConference,2005

[19]DeMango,F.,Liserre,M.,Dell’Aquila,A.,Pigazo,A.,“OverviewofAn3-islandingalgorithmsforPVSystems.PartI:PassiveMethods”,pp.1878-1883,PowerElectronicsandMo3onControlConference,2006

[20]DeMango,F.,Liserre,M.,Dell’Aquila,A.,Pigazo,A.,“OverviewofAn3-islandingalgorithmsforPVSystems.PartII:Ac3veMethods”,pp.1884-1889,PowerElectronicsandMo3onControlConference,2006

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[21]Xu,W.,Zhang,G.,Li,C.,Wang,W.,Wang,W.,Kliber,J.,“APowerLineSignalingBasedTechniqueforAn3-IslandingProtec3onofDistributedGenerators–PartI:SchemeandAnalysis”,IEEETransac3onsonPowerDelivery,Vo.22,No.3,July2007

[22]Hamzeh,M.,Farhangi,S.,Farhangi,B.,“ANewControlMethodinPVGridConnectedInvertersforAn3-IslandingProtec3onbyImpedanceMonitoring”,11thWorkshoponControlandModelingforPowerElectronics,2008

[23]Kunte,R.,Gao,W.,“ComparisonandReviewofIslandingDetec3onTechniquesforDistributedEnergyResources,”40thNorthAmericanPowerSymposium,2008

[24]Chiang,W.,Jou,H.,Wu,J.,Wu,K.,Feng,Y.,“Ac3veislandingdetec3onmethodforthegrid-connectedphotovoltaicgenera3onsystem”,ElectricPowerSystemsResearch,Vol80,pp.372–379,2009

[25]Wang,X.,Freitas,W.,Dinavahi,V.,Xu,W.,“Inves3ga3onofPosi3veFeedbackAn3-IslandingControlforMul3pleInverter-BasedDistributedGenerator”,IEEETransac3onsonPowerSystems,Vol.24,No.2,May2009

[26]Timbus,A.,Oudalov,A.,Ho,C.,“Islandingdetec3oninsmartgrids”,IEEEEnergyConversionCongressandExposi3on,2010

[27]Velasco,D.,Trujillo,C.Garcera,G.,Figueres,E.,“Reviewofan3-islandingtechniquesindistributedgenerators”,RenewableandSustainableEnergyReviews,Vol.14,pp.1608–1614,2010

[28]Yu,B.,Matsui,M.,Yu,G.,“Areviewofcurrentan3-islandingmethodsforphotovoltaicpowersystem”,SolarEnergy,Bol.84,pp.745-754,2010

[29]M.Hanif,M.BasuandK.Gaughan,:“ADiscussionofAn3-islandingProtec3onSchemesIncorporatedinaInverterBasedDG”,Interna3onalConferenceonEnvironmentandElectricalEngineering(EEEIC)2011,10thInterna3onal,8-11May2011

[30]Teoh,W.,Tan,C.,“AnOverviewofIslandingDetec3onMethodsinPhotovoltaicSystems”,Interna3onalJournalofElectrical,Computer,Energe3c,ElectronicandCommunica3onEngineeringVol:5,No:10,2011

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[31]Mills-Price,M.Scharf,M.,Hummel,S.,Ropp,M.Joshi,D.,Zweigle,G.,Ravikumar,K.,Flerchinger,B.,“SolarGenera3onControlWithTime-SynchronizedPhasors”64thAnnualConferenceforProtec3veRelayEngineers,2011

[32]Ropp,M.“AssessmentoftheUniversalFeasibilityofUsingpowerSystemHarmonicsasalossofMainsDetec3onforDistributedEnergyResources”,ReportfromContractRDF-3-21

[33]Khamis,A.,Shareef,H.Bizkevelci,E.,Kha3b,T.,“Areviewofislandingdetec3ontechniquesforrenewabledistributedgenera3onsystems”,RenewableandSustainableEnergyReviews,Vol.28,pp.483–493,2013

[34]Ahmad,K.,Selvaraj,J.,Rahim,N.,“Areviewoftheislandingdetec3onmethodsingrid-connectedPVinverters”,RenewableandSustainableEnergyReviews,Vol.21,pp.756–766,2013

[35]Daea,A.,Saha,D,Ray,A.,Das,P.,“An3-islandingselec3onforgrid-connectedsolarphotovoltaicsystemapplica3ons:AMCDMbaseddistanceapproach”,SolarEnergy,Vol110,pp.519-532,2014

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[38]Amendment1to1547™-2003IEEEStandardforInterconnec3ngDistributedResourceswithElectricPowerSystems

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