《电力系统继电保护及应用》课件-17. Vertical coupling differential protection and its testing

LongitudinaldifferentialprotectionanditstestingCONTENTSPAGELongitudinaldifferentialprotectionprinciple0102Fiber-opticlongitudinaldifferentialprotection03Fiber-opticlongitudinaldifferentialprotectiontestLongitudinaldifferentialprotectionprinciple01Longitudinal

differentialprotectionprincipleIntherelayprotectionofthepowersystem,currentprotectionanddistanceprotectionrelyonthesectionIoftheprotectiontoquicklyreactpartofthefaultoftheprotectedline;fortheendoftheline,theprotectedsectioncanonlyberemovedafteracertaindelay.Howtoquicklyremovethefaultthatoccursatanypointontheprotectedline?distanceprotectionUsingthesecondarycableorothercommunicationmeans,theprotectiondevicesatbothendsofthetransmissionlineareconnectedlongitudinally,andthecurrentorotherrelevantinformationatbothendsofthelineistransmittedtotheoppositeendforcomparativejudgment,soastoaccuratelydistinguishtheprotectiondeviceswithinternalandexternalfaults.LongitudinalCurrentDifferentialProtectionofTransmissionLinesLongitudinal

differentialprotectionprincipleMNILongitudinal

differentialprotectionprincipleMNI

Longitudinal

differentialprotectionprincipleWhenthelineisinnormaloperationandexternalfault

Longitudinal

differentialprotectionprincipleMNIWhenthereisaninternalfaultintheline

Longitudinal

differentialprotectionprincipleMNIFiber-opticlongitudinaldifferentialprotection02Fiber-opticlongitudinaldifferentialprotectionOpticalfiberlongitudinaldifferentialprotectionofthetransmissionlineisthelongitudinaldifferentialprotectionoftheopticalguidefiberasthecommunicationchannel.Withthedevelopmentofopticalfibercommunicationtechnology,theincreaseofopticalfiberproductionandthepricedecline,opticalfibercommunicationhasbecomethemaincommunicationmodeofthepowersystem.Withtherapidpopularizationoftheopticalfibercommunicationnetworkinthepowersystem,

opticalfiberlongitudinaldifferentialprotection,

asthemainprotectionofthehigh-voltagetransmissionlines,willgraduallyreplacethehigh-frequencyprotection.CommunicationcapacityislargeStronganti-interferenceabilityRawmaterialresourcesarerichEasytosetupFeaturesofopticalfibercommunicationFiber-opticlongitudinaldifferentialprotectionOpticalfibercurrentdifferentialprotectionMNM-sidecurrentdifferentialprotectionN-sidecurrentdifferentialprotectionFibreChannelFiber-opticlongitudinaldifferentialprotectionFiber-opticlongitudinaldifferentialprotectiontest03Fiber-opticlongitudinaldifferentialprotectiontestDuringtheopticalfiberdifferentialprotectiontest,asingle-modeopticalfiberisusedtoshort-circuitthereceivingandtransmittinginterfacesofthedevice,andthedifferentialprotectiontestisrealizedbyself-loopingthereceivingandsendingchannelsoftheprotectiondevicetosimulatetheworkingstateofself-transmittingandself-receiving.Fiber-opticlongitudinaldifferentialprotectiontestThencheckthedevicesettings,settheidentificationcodeofthelocalsideandtheidentificationcodeoftheoppositesidetobethesame,andinputthelongitudinaldifferentialcontrolword:Fiber-opticlongitudinaldifferentialprotectiontestCheckthesoftplaten,putinthelongitudinaldifferentialFiber-opticlongitudinaldifferentialprotectiontestTestusingthe"statesequence"functionofthemicrocomputerprotectiontesterState1:normalvoltageandcurrent,timetrigger,outputtimeis5S(thistimecanbesetarbitrarily)Fiber-opticlongitudinaldifferentialprotectiontestState2:Seta"differentialactioncurrent"of0.95times,inthisexample,thevalueis0.8,Needtoset0.8÷2×0.95=0.38.Thetriggerconditionistimetrigger,andtheoutputtimeis0.1S..Note:Therearethreestartingelements:mutationamountdifferentialflow,zero-orderdifferenceflow,andphasecurrentdifferenceflow.Theactualtestlogicismorecomplicatediftheinfluenceofthebrakingcurrentgeneratedbythecurrentsonbothsidesisconsidered.AfterapplyingtheFibrechannelself-loop(shortconnection),theactualdifferentialcurrentis2timesthatapplied,andthebrakecurrentis0orequaltothedifferentialcurrent.Thissimplifiesthetestscheme.Weonlyneed,andcanonlyverify,thelongitudinaldifferentialbyverifyingthe5%errorofthe"differentialactioncurrent".Status2thereforesets95times0differentialactioncurrent.Fiber-opticlongitudinaldifferentialprotectiontestState2:Seta"differentialoperatingcurrent"of0.95times.Inthisexample,thevalueis0.8.Needtoset0.8÷2×0.95=0.38.Thetriggerconditionistimetrigger,andtheoutputtimeis0.1S.Fiber-opticlongitudinaldifferentialprotectiontestState3:Seta"differentialactioncurrent"of1.05times.Inthisexample,thefixedvalueis0.8,Set0.8÷2×1.05=0.41.Thetriggerconditionisbinaryinputtrigger,or0.1Stimetrigger.Fiber-opticlongitudinaldifferentialprotectiontestNote:Theopticalfiberdifferentialprotectionhasatotalstart-upelementwithasuddenchange.Theappliedquantityneedstohaveasuddenchangebeforethedevicemayoperate.Therefore,when0.95timesthefixedvalue,thecurrentofphaseAisincreased,thecurrentdoesnotreachthefixedvalue,andtheprotectiondoesnotoperate.Instate3,thecurrentcannotbeincreasedonthebasisofstate2,otherwisetheamountofmutationmaynotbeenough,andonlythephasecanbechanged,andthephase