2023學(xué)年完整公開課版HighFrequencyProtectioninTransmissionLine高頻保護(hù)

項目五全線快速保護(hù)Project5

FastProtectioninAllLines任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

課程負(fù)責(zé)人：關(guān)嬌嬌、張勇CourseLeader：GuanJiaojiaoZhangYong任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

線路縱聯(lián)差動保護(hù)只適用于短線路，對于長線路縱聯(lián)差動保護(hù)不能采用。Linelongitudinaldifferentialprotectionisonlysuitableforshortline,forlonglinelongitudinaldifferentialprotectioncannotbeused.廣義高頻保護(hù)就是很好解決了縱聯(lián)差動保護(hù)的輔助導(dǎo)引線問題的一類保護(hù)。隨著解決方式的不同，稱謂也不一樣，即高頻保護(hù)、微波保護(hù)、光纖保護(hù)等。Generalizedhighfrequencyprotectionisakindofprotectionwhichcansolvetheproblemofauxiliaryguidelineoflongitudinaldifferentialprotection.

Withthesolutionofthedifferent,thetitleisnotthesame,thatis,highfrequencyprotection,microwaveprotection,fiberprotection,etc.任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

（1）高頻保護(hù)構(gòu)成

Compositionofhighfrequencyprotection任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

TrippingRelayprotectionpartReceiverSenderHighfrequencyprotectionHighfrequencychannelReceiverSenderRelayprotectionpartTripping（2）微波保護(hù)

Microwaveprotection任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

Channel(space)TrippingRelayprotectionpartReceiverSenderRelayprotectionpartTrippingReceiverSenderCommunicationpart（3）光纖保護(hù)構(gòu)成

Compositionofopticalfiberprotection任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

TrippingRelayprotectionpartReceiverSenderCommunicationpartRelayprotectionpartReceiverSenderPhotoelectricconversionPhotoelectricconversionFibrechannelTripping（1）高頻通道

Highfrequencychannel“相-地”制高頻通道的構(gòu)成。Thecompositionof"phase-ground"highfrequencychannel.任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

ReceiverSenderSenderReceiver高頻阻波器作用：由電感和電容構(gòu)成的并聯(lián)諧振回路，它串聯(lián)在線路兩端，從而將高頻信號限制在被保護(hù)線路上傳遞，而不致分流到其他線路上去。HighFrequencyResistorFunction:Aparallelresonantcircuitconsistingofaninductorandacapacitorconnectedinseriesatbothendsofacircuit,therebylimitingthetransmissionofhighfrequencysignalstotheprotectedcircuitratherthandivertingthemtoothercircuits.任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

ReceiverReceiverSenderSender

耦合電容器的作用：將低壓高頻設(shè)備輸出的高頻信號耦合到高壓線路上。CouplingCapacitor:Couplinghigh-frequencysignalsfromlow-voltageandhigh-frequencyequipmenttohigh-voltagelines.任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

ReceiverReceiverSenderSender連接濾波器：繞組匝數(shù)可以調(diào)節(jié)的變壓器。在其連接高頻電纜的一側(cè)串接電容器，連接濾波器與耦合電容器共同組成高頻串聯(lián)諧振回路，讓高頻電流順利通過。Connectionfilter:transformerwhosewindingturnscanbeadjusted.

Thecapacitorisconnectedinseriesonthesideofthehigh-frequencycable,andthefilterandthecouplingcapacitorareconnectedtogethertoformahigh-frequencyseriesresonantloop,sothatthehigh-frequencycurrentcanpasssmoothly.ReceiverReceiverSenderSender高頻電纜：用來連接高頻收、發(fā)信機(jī)與連接濾波器。Highfrequencycable:usedtoconnectthehighfrequencyreceiverandtransmitterwiththeconnectionfilter.SenderSenderReceiverReceiver在檢查調(diào)試高頻保護(hù)時，應(yīng)將接地刀閘合上，以保證人身安全。放電間隙用以防止過電壓對收、發(fā)信機(jī)的傷害。Whencheckinganddebuggingthehighfrequencyprotection,thegroundingswitchshouldbeclosedtoensurepersonalsafety.

Dischargegapisusedtopreventover-voltagedamagetoreceiverandtransmitter.SenderSenderReceiverReceiver收、發(fā)信實際為一體機(jī)，收信部分具有放大、解調(diào)接收的高頻信號的作用。Receivingandsendingareactuallyintegratedmachines,andthereceivingparthasthefunctionofamplifyinganddemodulatingthereceivedhigh-frequencysignals.SenderSenderReceiverReceiver啟動方式:Startingmethod故障啟動發(fā)信長時發(fā)信移頻發(fā)信FailuretostartsendingmessagesLonglettersFrequentmovingletter任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

（2）高頻信號與高頻電流關(guān)系Relationshipbetweenhighfrequencysignalandhighfrequencycurrent故障啟動方式：電力系統(tǒng)正常運(yùn)行時收發(fā)信機(jī)不發(fā)信，通道中無高頻電流。當(dāng)電力系統(tǒng)故障時，起動元件啟動收發(fā)信機(jī)發(fā)信。Faultstartmode:whenthepowersystemisrunningnormally,thetransceiverdoesnotsendmessages,andthereisnohigh-frequencycurrentinthechannel.

Whenthepowersystemfails,thestarterelementstartsthetransceivertosendmessages.優(yōu)點：對鄰近通道的影響小，可以延長收發(fā)信機(jī)的壽命。Advantages:littleimpactonadjacentchannels,canextendtransceiverlife.缺點：必須有啟動元件，且需要定時檢查通道是否良好。Disadvantages:Musthaveastarterelement,andneedstoperiodicallycheckthechannelisgood.任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

長期發(fā)信方式：電力系統(tǒng)正常運(yùn)行時，收發(fā)信機(jī)連續(xù)發(fā)信，高頻電流持續(xù)存在，用于監(jiān)視通道是否完好。而高頻電流的消失代表高頻信號。Long-termsendingmode:whenthepowersystemisrunningnormally,thetransceiversendsmessagescontinuouslyandthehigh-frequencycurrentcontinuestoexist,whichisusedtomonitorwhetherthechannelisingoodcondition.

Thedisappearanceofthehighfrequencycurrentrepresentsthehighfrequencysignal.優(yōu)點：通道的工作狀態(tài)受到監(jiān)視，可靠性高。Advantages:theworkingstatusofthechannelismonitored,andthereliabilityishigh.缺點：增大了通道間的干擾，并降低了收發(fā)信機(jī)的使用年限。Disadvantages:increasestheinterferencebetweenchannelsandreducestheservicelifeofthetransceiver.任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

移頻發(fā)信方式:Movefrequencysignalsendingmode正常運(yùn)行時發(fā)出頻率的高頻電流，用于監(jiān)視通道。Highfrequencycurrentoffrequencyf2isemittedduringnormaloperationformonitoringchannels.故障時，收發(fā)信機(jī)發(fā)出頻率為的高頻電流,頻率為的高頻電流代表高頻信號。Whenafaultoccurs,thetransceiveremitsahigh-frequencycurrentoffrequencyF2,whichrepresentsahigh-frequencysignal.（3）高頻信號的作用

Theroleofhighfrequencysignals任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

ProtectiveelmentsProtectiveelmentsSignallockingSignalallowingSignaltrippingTrippingpulseTrippingpulseTrippingpulseProtectiveelments閉鎖信號是阻止保護(hù)動作于跳閘的信號。換言之，無閉鎖信號是保護(hù)作用于跳閘的必要條件。Thelatchingsignalisasignalthatpreventstheprotectionactionfromtripping.

Inotherwords,non-latchingsignalisanecessaryconditiontoprotectagainsttripping.允許信號是允許保護(hù)動作于跳閘的信號。有允許信號是保護(hù)動作于跳閘的必要條件。Theallowablesignalisthesignalthatallowstheprotectionactiontotrip.

Permissionsignalisanecessaryconditiontoprotectactionfromtripping.任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

ProtectiveelmentsProtectiveelmentsProtectiveelmentsTrippingpulseTrippingpulseTrippingpulseSignallockingSignalallowingSignaltripping跳閘信號是直接引起跳閘的信號,收到跳閘信號是跳閘的充要條件。Trippingsignalisthesignalthatdirectlycausestripping,andreceivingthetrippingsignalisanecessaryandsufficientconditionfortripping.3、高頻閉鎖方向保護(hù)Highfrequencyblockingdirectionalprotection任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

ProtectiveelmentsProtectiveelmentsProtectiveelmentsSignallockingTrippingpulseTrippingpulseTrippingpulseSignalallowingSignaltripping原理：根據(jù)被保護(hù)線路兩側(cè)的方向元件分別對短路的方向作出判斷，并利用高頻信號作出綜合判斷，進(jìn)而決定是否跳閘的一種保護(hù)。Principle:accordingtothedirectionelementsonbothsidesoftheprotectedlinetojudgethedirectionoftheshortcircuit,andusethehighfrequencysignaltomakeacomprehensivejudgment,andthendecidewhethertotripaprotection.發(fā)信方式：國內(nèi)廣泛應(yīng)用的高頻閉鎖方向保護(hù)用故障啟動發(fā)信方式，并規(guī)定線路兩端功率由母線指向線路為正方向，由線路指向母線為反方向。Sendingmode:thehighfrequencyblockingdirectionprotectionwhichiswidelyusedinChinausesthefaultstartsendingmode,anditisstipulatedthatthepoweratbothendsofthelinepointstothelinefromthebustothepositivedirection,andthelinepointstothebustothenegativedirection.要求：故障時在啟動元件靈敏度范圍內(nèi)應(yīng)可靠啟動發(fā)信及啟動保護(hù)。Requirement:Incaseoffailure,thetransmitterandprotectionshouldbereliablystartedwithinthesensitivityrangeofthestarterelement.任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

方向元件：正向時使高頻收、發(fā)信機(jī)停信。反向時，高頻收、發(fā)信機(jī)繼續(xù)發(fā)信。Directionelement:tostopthehighfrequencyreceiverandsenderintheforwarddirection.

Inthereversedirection,thehighfrequencyreceiverandtransmittercontinuetosendmessages.電力系統(tǒng)正常運(yùn)行時，啟動元件不啟動，高頻收、發(fā)信機(jī)不發(fā)信，保護(hù)不開放。Whenthepowersystemisrunningnormally,thestartingelementdoesnotstart,thehigh-frequencyreceiverandtransmitterdonotsendmessages,andtheprotectionisnotopen.任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

StartingelementsPowerdirectionelementWiringdiagramProtectiveblockdiagramTripSenderReceiverChannelForbiddenexitForbiddenexit任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

WiringdiagramStartingelementsPowerdirectionelementProtectiveblockdiagramForbiddenexitForbiddenexitSenderReceiverTripChannel當(dāng)BC線路故障時：線路AB、BC上的高頻保護(hù)均分別起動發(fā)信。WhentheBClinefails:thehighfrequencyprotectiononlineABandBCstartssendingmessagesrespectively.保護(hù)1方向元件判斷正方向，與門有輸出，經(jīng)t2延時使本側(cè)高頻收、發(fā)信機(jī)停信，另一方面經(jīng)禁止門2準(zhǔn)備出口跳閘。因保護(hù)2的方向元件判斷故障為反方向，與門無輸出，高頻收、發(fā)信機(jī)連續(xù)發(fā)出高頻信號，閉鎖本側(cè)保護(hù)。Theprotection1directionelementjudgesthepositivedirectionandhasanoutputwiththedoor.AftertheT2delay,thehighfrequencyreceiverandsenderatthissidewillstopthemessage.Ontheotherhand,thegate2willpreparetheexittrip.

Becausethefaultofthedirectionelementofprotection2isjudgedtobeintheoppositedirection,andthereisnooutputfromthegate,thehigh-frequencyreceiverandtransmittersendouthigh-frequencysignalscontinuouslytoblocktheprotectionofthelocalside.WiringdiagramStartingelementsPowerdirectionelementProtectiveblockdiagramForbiddenexitForbiddenexitTripSenderReceiverChannel記憶元件KT1的作用是防止外部故障切除后，近故障點側(cè)的保護(hù)啟動元件先返回停止發(fā)信，而遠(yuǎn)故障點側(cè)的啟動元件和功率方向元件后返回，造成保護(hù)誤動作跳閘。ThefunctionofmemoryelementKT1istopreventtheprotectionstartingelementnearthefaultpointfromreturningtostopsendingaftertheexternalfaultisremoved,whilethestartingelementandpowerdirectionelementatthefarfaultpointreturntostopsendingaftertheexternalfaultisremoved,resultingintheprotectionmisoperationtripping.WiringdiagramStartingelementsPowerdirectionelementProtectiveblockdiagramForbiddenexitForbiddenexitTripSenderReceiverChannel4、相差高頻保護(hù)

Differentialhighfrequencyprotection原理：比較被保護(hù)線路兩側(cè)電流的相位，即利用高頻信號將電流的相位傳送到對側(cè)去進(jìn)行比較，稱為相差高頻保護(hù)。Principle:Comparethephaseofthecurrentonbothsidesoftheprotectedline,thatis,thephaseofthecurrentistransmittedtotheoppositesidebyusingthehighfrequencysignalforcomparison,whichiscalledthephasedifferencehighfrequencyprotection.假設(shè)：線路兩側(cè)的電勢同相，系統(tǒng)各元件的阻抗角相同（實際上有差別的）。Assumption:thepotentialonbothsidesofthelineisinthesamephase,andtheimpedanceAngleofeachelementinthesystemisthesame(actuallythereisadifference).任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

ProtectionProtectionThesamephaseReverse,180degreesoutofphase為實現(xiàn)比相，須把線路對端的電流的信號傳送到本端且能代表原工頻電流的相位，由比相系統(tǒng)給出比較結(jié)果。Inordertorealizethephasecomparison,thecurrentsignaloftheoppositeendofthelinemustbetransmittedtothisendandcanrepresentthephaseoftheoriginalworkingfrequencycurrent.Thecomparisonresultisgivenbythephasecomparisonsystem.若兩側(cè)電流相位差近于0°時，保護(hù)判斷為被保護(hù)范圍內(nèi)部故障，應(yīng)瞬時動作切除故障。Ifthephasedifferencebetweenthetwosidesofthecurrentiscloseto0°,theprotectionisjudgedtobeaninternalfaultwithintheprotectedrange,andthefaultshouldberemovedbyinstantaneousaction.若兩側(cè)流相位差接近于180°時，保護(hù)判斷為外部故障，應(yīng)可靠將保護(hù)閉鎖。Ifthephasedifferencebetweenthetwosidesoftheflowiscloseto180°,theprotectionisjudgedtobeanexternalfault,andtheprotectionshouldbereliablylocked.任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

當(dāng)短路電流為正半周時，高頻發(fā)信機(jī)發(fā)出高頻信號，而在負(fù)半周時則不發(fā)出信號。Whentheshortcircuitcurrentispositivehalfcycle,thehighfrequencytransmittersendsoutthehighfrequencysignal,butdoesnotsendoutthesignalatthenegativehalfcycle.當(dāng)被保護(hù)范圍內(nèi)部故障時，由于兩側(cè)同時發(fā)出高頻信號，也同時停止發(fā)信。在兩側(cè)收信機(jī)收到的高頻信號是間斷的。Whenthefaultoccurswithintheprotectedrange,thetransmissionstopsatthesametimebecausebothsidessendouthighfrequencysignals.

Thehighfrequencysignalsreceivedbythereceiversonbothsidesareintermittent.

當(dāng)被保護(hù)范圍外部故障時，由于兩側(cè)電流相位相差180°，線路兩側(cè)的發(fā)信機(jī)交替工作，收信機(jī)收到的高頻信號是連續(xù)的高頻信號。Whenthefaultoccursoutsidetheprotectedrange,duetothecurrentphasedifferenceof180°onbothsides,thetransmitteronbothsidesofthelineworksalternatively,andthehigh-frequencysignalreceivedbythereceiveriscontinuoushigh-frequencysignal.任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

CurrentwaveformonbothsideshighfrequencysignalonMsidehighfrequencysignalonNsideThehighfrequencysignalreceivedbythereceiveronbothsides結(jié)論：（區(qū)內(nèi)故障）兩側(cè)收信機(jī)收到的高頻信號重疊約10ms，保護(hù)瞬時動作跳閘。即使內(nèi)部故障時高頻通道遭破壞，不能傳送高頻信號，但收信機(jī)仍能收到本側(cè)發(fā)信機(jī)發(fā)出的間斷高頻信號，因而不會影響保護(hù)跳閘。Conclusion:thehighfrequencysignalreceivedbybothsidesofthereceiveroverlapsabout10ms,whichprotectstheinstantaneousactiontrip.

Evenifthehighfrequencychannelisdestroyedandthehighfrequencysignalcannotbetransmittedduringtheinternalfault,thereceivercanstillreceivetheintermittenthighfrequencysignalsentbythetransmitteronitsside,sotheprotectiontripwillnotbeaffected.保護(hù)區(qū)外故障：兩側(cè)的收信機(jī)收到的高頻信號是連續(xù)的，線路兩側(cè)的高頻信號互為閉鎖，使兩側(cè)保護(hù)不能跳閘。Faultoutsidetheprotectionzone:thehigh-frequencysignalsreceivedbythereceiversonbothsidesofthelinearecontinuous,andthehigh-frequencysignalsonbothsidesofthelineblockeachother,sothattheprotectiononbothsidescannottrip.任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

小結(jié)：1）高頻閉鎖方向保護(hù)是比較線路兩側(cè)功率方向，兩側(cè)均為正方向時保護(hù)動作；有一側(cè)為反方向時，閉鎖保護(hù)。Summary:1)Highfrequencyblockingdirectionalprotectionisaprotectionactionwhenthepowerdirectionsonbothsidesofthelinearecomparedandbothsidesareinpositivedirections;

Whenonesideisintheoppositedirection,lockprotection.2）相差高頻保護(hù)是比較線路兩側(cè)電流的相位，相位相近時保護(hù)動作；反相時保護(hù)閉鎖。Differencehighfrequencyprotectionistocomparethephaseofthecurrentonbothsidesoftheline,theprotectionactionwhenthephaseisclose;

Protectionlatchduringphasereversal.發(fā)信方式：故障發(fā)信、長期發(fā)信、移頻發(fā)信。Sendingmode:faultsending,long-termsending,movingfrequentsending.任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

高頻信號：跳閘信號、允許信號、閉鎖信號。Highfrequencysignal:trippingsignal,allowingsignal,blockingsignal.高頻電流與高頻信號關(guān)系：長期發(fā)信，高頻電流消失代表高頻信號。故障發(fā)信，高頻電流代表高頻信號。Therelationshipbetweenhighfrequencycurrentandhighfrequencysignal:sendingsignalsforalongtime,thedisappearanceofhighfrequencycurrentrepresentsthehighfrequencysignal.

Faultsending,highfrequencycurrentrepresentshighfrequencysignal.移頻信號：高頻電流代表高頻信號。Frequencyshiftsignal:thehighfrequencycurrentrepresentsthehighfrequencysignalf2.任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

光纖通道容量大、抗腐蝕、敷設(shè)及檢修方便，可節(jié)省大量有色金屬；可解決縱聯(lián)保護(hù)中導(dǎo)引線保護(hù)及高頻保護(hù)的通道易受電磁干擾、高頻信號衰耗等問題。Thefiberchannelhaslargecapacity,corrosionresistance,convenientlayingandmaintenance,andcansavealotofnon-ferrousmetals.

Itcansolvetheproblemssuchaselectromagneticinterferenceandhighfrequencysignaldecayinthechannelofthelongitudinalprotectionandhighfrequencyprotection.1.架空地線復(fù)合光纜（OPGW）的結(jié)構(gòu)、特征Structureandcharacteristicsofoverheadgroundcompositeopticalcable(OPGW)任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

復(fù)合光纜地線具有2種功能，一是作為輸電線路的避雷線；二是通過復(fù)合在地線中的光纖，是傳送光信號的介質(zhì)，可傳送音頻、視頻、數(shù)據(jù)和各種控制信號，組建多路寬帶通信網(wǎng)。Thegroundwireofcompositeopticalcablehastwofunctions.Oneisasalightningconductorfortransmissionlines.

Thesecondisthroughthecompositeopticalfiberintheground,isthetransmissionofopticalsignalmedium,cantransmitaudio,video,dataandavarietyofcontrolsignals,theformationofamulti-channelbroadbandcommunicationnetwork.

2.光纖通信的特點

Characteristicsofopticalfibercommunication1）通信容量大。Largecommunicationcapacity.2）節(jié)約大量金屬材料Savealotofmetalmaterials任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

3）光纖通信還有保密性好，敷設(shè)方便，不怕雷擊，不受外界電磁干擾，抗腐蝕和不怕潮等優(yōu)點。Fiberopticcommunicationalsohastheadvantagesofgoodconfidentiality,convenientlaying,notafraidoflightningstrike,notaffectedbyexternalelectromagneticinterference,corrosionresistanceandnotafraidofmoisture.

4）光纖最重要的特性之一是無感應(yīng)性能，因此利用光纖可以構(gòu)成無電磁感應(yīng)的、極為可靠的通道。Oneofthemostimportantcharacteristicsofopticalfiberisthenon-inductionperformance,sotheuseofopticalfibercanbeconstructedwithoutelectromagneticinduction,extremelyreliablechannel.3、光纖保護(hù)的組成

Compositionofopticalfiberprotection任務(wù)二輸電線路高頻保護(hù)Task2HighFrequencyProtectioninTransmissionLine

ElectricparametersElectricparametersElectricparametersElectricparametersRelayprotectionRelayprotectionmodulatormodulatormodemmodemPCMtransmitterjointPCMtransmitterjointOpticalcablereceiverOpticalcablereceiverOpticalcablereceiverOpticalcablereceiverOpticaltransceiverOpticaltransceiverMovableconnectorFiberopticcableMovableconnectorMovableconnector由故障判別元件（繼電保護(hù)部分）和信號傳輸系統(tǒng)（PCM端機(jī)、光端機(jī)以及光纜通道）組成Itiscomposedoffaultidentificationelement(relayprotectionpart)andsignaltransmissionsystem(PCMterminal,opticalterminalandopticalcablechannel)PCM端機(jī)由PCM調(diào)制器和PCM解調(diào)器組成。PCM(PulseCodeModulation)調(diào)制器的原理是脈沖編碼調(diào)制。PCMterminalconsistsofaPCMmodulatorandaPCMdemodulator.APCM(PulseCodeModulation)modulatorisbasedonPulseCodeModulation.ElectricparametersElectricparametersRelayprotectionRelayprotectionmodulatormodulatormodemmodemPCMtransmitterPCMtransmitterOpticalcablesenderOpticalcablesenderOpticaltr