數(shù)字繼電器的要點(diǎn)、特點(diǎn)和重要注意事項(xiàng).docx

1、TheEssentialsOfNumericalRelays,TheirFeaturesAndImportantConsiderations數(shù)字繼電器的要點(diǎn)、特點(diǎn)和重要注意事項(xiàng)gByEdvardIntroductiontonumericalrelays數(shù)字繼電器簡介ThedistinctionbetweendigitalandnumericalrelaysisparticulartoProtection.Numericalrelaysarenaturaldevelopmentsofdigitalrelaysduetoadvancesintechnology.Theyuseoneormoredi

2、gitalsignalprocessors(DSP)optimisedforrealtimesignalprocessing,runningthemathematicalalgorithmsfortheprotectionfunctions.數(shù)字繼電器和數(shù)值繼電器的區(qū)別在于保護(hù)。由于技術(shù)的進(jìn)步，數(shù)字繼電器是數(shù)值繼電器的自然發(fā)展。它們使用一個(gè)或多個(gè)為實(shí)時(shí)信號處理而優(yōu)化的數(shù)字信號處理器(DSP),運(yùn)行保護(hù)功能的數(shù)學(xué)算法。SRAMAlarm,event,faultdisturbance&maintenancerecordsSRAMExecutablecode&data,setting

3、databasedataFlashmemoryDefaultsettings&paramaters,languagetext,code,presentsettings441MainprocessorboardFrontLCDdisplay卜CPU.FPGAIRIG-BSignal.IRIG-BEthernetcommsEthernetEthernetandIRIG-BboardRelayboardSQSUOO>0505InHno£e布p一3一sCommsbetweenmainandcoprocessorboardCoprocessorboardPowersupplyRe

4、arcommsdataPowerSupplyBoardt;PowerWatchdogsupplycontactsRearRS485comms號du二5一60to-utsppoinInputboardAnalogueInputsignalsTransformerBoardCurrentandvoltageinputsFigure6-Typicalnumericalrelayhardwarearchitecture圖6典型的數(shù)字繼電器硬件結(jié)構(gòu)ByorganisingtheI/Oonasetofplug-inprintedcircuitboards(PCBs),additionalI/Ouptoth

5、elimitsofthehardware/softwarecanbeeasilyadded.Theinternalcommunicationsbuslinksthehardwareandthereforeisacriticalcomponentinthedesign.Itmustworkathighspeed,uselowvoltages,yetbeimmunetoconductedandradiatedinterferencefromtheelectricallynoisysubstationenvironment.Excellentshieldingoftherelevantareasis

6、thereforerequired.Digitalinputsareopticallyisolatedtopreventtransientsbeingtransmittedtotheinternalcircuitry.Analogueinputsareisolatedusingprecisiontransformerstomaintainmeasurementaccuracywhileremovingharmfultransients.Additionally,theinputsignalsmustbeamplitudelimitedtoavoidthemexceedingthemeasure

7、mentrange,otherwisethewaveformisclipped,introducingharmonics.SeeFigure7.通過在一組插入式印刷電路板(PCB)上組織I/O,可以輕松添加不超過硬件/軟件限制的額外I/O。內(nèi)部通信總線連接硬件，因此是設(shè)計(jì)中的關(guān)鍵組件。它必須高速工作，使用低電壓，但不受電氣噪聲變電站環(huán)境的傳導(dǎo)和輻射干擾。因此，需要對相關(guān)區(qū)域進(jìn)行良好的屏蔽。數(shù)字輸入是光學(xué)隔離的，以防止瞬態(tài)傳輸?shù)絻?nèi)部電路。模擬輸入使用精密變壓器隔離，以保持測量精度，同時(shí)消除有害瞬變。此外，必須限制輸入信號的振幅，以避免其超出測量范圍，否則波形會(huì)被截?cái)啵瑥亩胫C波。參見圖7oFi

8、gure7-Clippingduetoexcessiveamplitude圖7-振幅過大導(dǎo)致的削波AnaloguesignalsareconvertedtodigitalformusinganA/Dconverter.ThecheapestmethodistouseasingleA/Dconverter,precededbyamultiplexertoconnecteachoftheinputsignalsinturntotheconverter.Thesignalsmaybeinitiallyinputtoseveralsimultaneoussample-and-holdcircuitsb

9、eforemultiplexing,orthetimerelationshipbetweensuccessivesamplesmustbeknownifthephaserelationshipbetweensignalsisimportant.ThealternativeistoprovideeachinputwithadedicatedA/Dconverterandlogictoensurethatallconvertersperformthemeasurementsimultaneously.Thefrequencyofsamplingmustbecarefullyconsidered,a

10、stheNyquistcriterionapplies:模擬信號通過A/D轉(zhuǎn)換器轉(zhuǎn)換成數(shù)字形式。最便宜的方法是使用一個(gè)a/D轉(zhuǎn)換器，前面是一個(gè)多路復(fù)用器，將每個(gè)輸入信號依次連接到轉(zhuǎn)換器。在多路復(fù)用之前，信號可能首先輸入到多個(gè)同時(shí)采樣和保持電路，或者如果信號之間的相位關(guān)系很重要，則必須知道連續(xù)采樣之間的時(shí)間關(guān)系。另一種方法是為每個(gè)輸入端提供專用的a/D轉(zhuǎn)換器和邏輯，以確保所有轉(zhuǎn)換器同時(shí)執(zhí)行測量。必須仔細(xì)考慮采樣頻率，因?yàn)槟慰固貥?biāo)準(zhǔn)適用:fs>2xfhwhere:此處fs=samplingrate采樣率.fh=highestfrequencyofinterest最高有效頻率Ifthesam

11、plingfrequencyistoolow,aliasingoftheinputsignalcanoccur(seeFigure8)sothathighfrequenciescanappearaspartofthesignalinthefrequencyrangeofinterest.Incorrectresultsarethenobtained.Thesolutionistouseananti-aliasingfilterandthecorrectsamplingfrequencyontheanaloguesignal,filteringoutthefrequencycomponentst

12、hatcouldcausealiasing.Digitalsineandcosinefilters(Figure7)extracttherealandimaginarycomponentsofthesignal.如果采樣頻率過低，可能會(huì)出現(xiàn)輸入信號的混疊(見圖8),因此高頻會(huì)作為感興趣的頻率范圍內(nèi)的信號的一部分出現(xiàn)。然后得到錯(cuò)誤的結(jié)果。解決方案是對模擬信號使用抗混疊濾波器和正確的采樣頻率，過濾掉可能導(dǎo)致混疊的頻率分量。數(shù)字正弦和余弦濾波器（圖7）提取信號的實(shí)部和虛部。Figure8一Signalaliasingproblem圖8-信號混疊問題RelayOperatingSystemSoftwa

13、re2. 繼電器操作系統(tǒng)軟件Thesoftwareprovidediscommonlyorganisedintoaseriesoftasksoperatinginrealtime.AnessentialcomponentistheRealTimeOperatingSystem(RTOS)whichensuresthattheothertasksareexecutedwhenrequired,inthecorrectpriority.Othersoftwaredependsonthefunctionoftherelay,butcanbegeneralizedasfollows:1. System

14、servicessoftware一ThisiscomparablewiththeBIOSofanordinaryPCandcontrolsthelow-levelI/Ofortherelaysuchasdriversfortherelayhardwareandboot-upsequence.2. HMIinterfacesoftware-Thisisthehighlevelsoftwareforcommunicatingwithauseronthefrontpanelcontrolsorthroughadatalinktoanothercomputertostoredatasuchassett

15、ingsoreventrecords.3. Applicationsoftware-ThisisthesoftwarethatdefinestheprotectionfunctionoftherelayAuxiliaryfunctions-Softwaretoimplementotherfeaturesintherelay,oftenstructuredasaseriesofmodulestoreflecttheoptionsofferedbythemanufacturer.提供的軟件通常被組織成一系列實(shí)時(shí)運(yùn)行的任務(wù)。一個(gè)重要組件是實(shí)時(shí)操作系統(tǒng)（RTOS）,它確保在需要時(shí)以正確的優(yōu)先級執(zhí)行其他

16、任務(wù)。其他軟件取決于繼電器的功能，但可概括如下：1. 系統(tǒng)服務(wù)軟件-這與普通PC的BIOS相當(dāng)，并控制繼電器的低級I/O,如繼電器硬件的驅(qū)動(dòng)程序和啟動(dòng)順序。2. 人機(jī)界面軟件-這是一種高級軟件，用于在前面板控件上與用戶通信，或通過數(shù)據(jù)鏈路與另一臺(tái)計(jì)算機(jī)通信，以存儲(chǔ)設(shè)置或事件記錄等數(shù)據(jù)。3. 應(yīng)用軟件-這是定義繼電器保護(hù)功能的軟件4.輔助功能-在繼電器中實(shí)現(xiàn)其他功能的軟件，通常結(jié)構(gòu)為一系列模塊，以反映制造商提供的選項(xiàng)。3. RelayApplicationSoftware繼電器應(yīng)用軟件Therelevantsoftwarealgorithmisthenapplied.Firstlythequan

17、titiesofinterestaredeterminedfromtheinformationinthedatasamples.ThisisoftendoneusingaDiscreteFourierTransform(DFT)andtheresultismagnitudeandphaseinformationfortheselectedquantity.Thiscalculationisrepeatedforallofthequantitiesofinterest.Thequantitiescanthenbecomparedwiththeelaycharacteristic,andadeci

18、sionmadeintermsofthefollowing: Valueabovesetting一starttimers,etc. Timerexpired-actionalarm/tripValuereturnedbelowsetting-resettimers,etc. Valuebelowsetting-donothingValuestillabovesetting一incrementtimer,etc.Sincetheoverallcycletimeforthesoftwareisknown,timersaregenerallyimplementedascounters.然后應(yīng)用相關(guān)的

19、軟件算法。首先，根據(jù)數(shù)據(jù)樣本中的信息確定感興趣的數(shù)量。這通常是使用離散傅里葉變換(DFT)完成的，其結(jié)果是選定量的幅值和相位信息。對所有感興趣的量重復(fù)此計(jì)算。然后可以將這些量與繼電器特性進(jìn)行比較，并根據(jù)以下內(nèi)容做出決定：,-啟動(dòng)計(jì)時(shí)器等。高于設(shè)設(shè)置-行動(dòng)警報(bào)/跳閘計(jì)時(shí)器已過期-重置計(jì)時(shí)器等。返回的值低于設(shè)置-什么都不做低于設(shè)設(shè)置-遞增計(jì)時(shí)器等。數(shù)值仍高于設(shè)設(shè)置由于軟件的總循環(huán)時(shí)間是已知的，所以定時(shí)器通常被實(shí)現(xiàn)為計(jì)數(shù)器。AdditionalFeaturesOfNumericalRelays數(shù)字繼電器的附加功能Thedigitalsignalprocessor(DSP)inanumericalre

20、laynormallycanhandleboththerelayprotectionfunctioncalculationsandgeneralmanagementoftherelaysuchasHMIandI/O.However,iftheDSPisoverloadeditcannotcompletetheprotectionalgorithmcalculationsintherequiredtimeandtheprotectionfunctionisslowed.Typicalfunctionsthatmaybefoundinanumericalrelayotherthanprotecti

21、onfunctionsaredescribedinthissection.Notethatnotallfunctionsarefoundinaparticularrelay.Aswithearliergenerationsofrelaysandaccordingtomarketsegmentation,manufacturersofferdifferentversions,eachwithadifferentsetoffunctions.Functionparametersareusuallydisplayedonthefrontpaneloftherelayandthroughanexter

22、nalcommunicationsport.1. MeasuredValuesDisplayVT/CTSupervision2. CBContol/StateIndication/ConditionMonitorinqDisturbanceRecorder(Oscillograph)3. TimeSynchronizationPoqammableLoqic4. ProvisionofSettingGroupsContusions數(shù)字繼電器中的數(shù)字信號處理器(DSP)通?？梢蕴幚砝^電器保護(hù)功能計(jì)算和繼電器的一般管理，如HMI和I/O。但是，如果DSP過載，則無法在要求的時(shí)間內(nèi)完成保護(hù)算法計(jì)算，且

23、保護(hù)功能變慢。本節(jié)介紹了數(shù)字繼電器中除保護(hù)功能以外的典型功能。請注意，并非所有功能都存在于特定繼電器中。與前幾代繼電器一樣，根據(jù)市場細(xì)分，制造商提供不同版本的繼電器，每個(gè)繼電器具有不同的功能。功能參數(shù)通常顯示在繼電器的前面板上，并通過外部通信端口顯示。1. 測量值顯示2. VT/CT監(jiān)督3. CB控制/狀態(tài)指示/狀態(tài)監(jiān)測4. 干擾記錄器(示波器)5. 時(shí)間同步6. 可編程邏輯7. 提供布景組8. 結(jié)論MeasuredValuesDisplay1.測量值顯示Thisisperhapsthemostobviousandsimplefunctiontoimplement,asitinvolvesth

24、eleastadditionalprocessortime.Thevaluesthattherelaymustmeasuretoperformitsprotectionfunctionhavealreadybeenacquiredandprocessed.Itisthereforeasimpletasktodisplaythemonthefrontpanel,ortransmitthemtoaremotecomputerorHMIstation.Severalextraquantitiesmaybederivedfromthemeasuredquantities,dependingonthei

25、nputsignalsavailable.Thesemightinclude: Sequencequantities(positive,negative,zero)Power,reactivepowerandpowerfactor Energy(kWh,kVArh)Max.demandinaperiod(kW,kVAr;averageandpeakvalues) HarmonicquantitiesFrequency Temperatures/RTDstatusMotorstartinformation(starttime,totalno.ofstarts/reaccelerations,to

26、talrunningtime DistancetofaultTheaccuracyofthemeasuredvaluescanonlybeasgoodastheaccuracyofthetransducersusedsuchasVTsCTs,andtheA/Dconverter.AsCTsandVTsforprotectionfunctionsmayhaveadifferentaccuracyspecificationtothoseformeteringfunctions,suchdatamaynotbesufficientlyaccuratefortariffpurposes.這可能是實(shí)現(xiàn)最

27、明顯、最簡單的函數(shù)，因?yàn)樗婕暗念~外處理器時(shí)間最少。繼電器為執(zhí)行其保護(hù)功能而必須測量的值已被采集和處理。因此，在前面板上顯示或?qū)⑵鋫鬏數(shù)竭h(yuǎn)程計(jì)算機(jī)或HMI站是一項(xiàng)簡單的任務(wù)。根據(jù)可用的輸入信號，可以從測量的量中導(dǎo)出幾個(gè)額外的量。這些可能包括：序列量（正、負(fù)、零）功率、無功功率和功率因數(shù),能量（千瓦時(shí)，千瓦時(shí)）一段時(shí)間內(nèi)的最大需求（千瓦、千伏安；平均值和峰值）諧波量頻率-溫度/RTD狀態(tài)電機(jī)啟動(dòng)信息（啟動(dòng)時(shí)間、啟動(dòng)/再加速總次數(shù)、總運(yùn)行時(shí)間-到斷層的距離測量值的精度只能與所用傳感器（如VTsCTs和A/D轉(zhuǎn)換器）的精度相同。由于用于保護(hù)功能的CT和VT的精度規(guī)格可能與用于計(jì)量功能的CT和VT的精

28、度規(guī)格不同,因此此類數(shù)據(jù)可能不足以用于電價(jià)目的。However,itissufficientlyaccurateforanoperatortoassesssystemconditionsandmakeappropriatedecisions.然而,它足夠準(zhǔn)確,操作員可以評估系統(tǒng)狀況并做出適當(dāng)?shù)臎Q策。1. VT/CTSupervisionTheEssentialsOfNumericalRelays,TheirFeaturesAndImportantConsiderations數(shù)字繼電器的要點(diǎn)、特點(diǎn)和重要注意事項(xiàng)Thecontinuingreductioninthecostandsizeofmic

29、roprocessors,memoryandI/Ocircuitryleadstoasingleitemofhardwareforarangeoffunctions.Forfasterrealtimeprocessingandmoredetailedanalysisofwaveforms,severalDSPscanberuninparallel.Manyfunctionspreviouslyimplementedinseparateitemsofhardwarecanthenbeincludedinasingleitem.OkJet'sstartwithintroductionton

30、umericalrelays,thenexplainingtheiradditionalfeaturesandattheendtodiscussimportantconsiderationsregardingsoftware,datamanagement,etc.微處理器、存儲(chǔ)器和I/O電路的成本和尺寸的持續(xù)降低導(dǎo)致了一系列功能的單一硬件。為了更快地實(shí)時(shí)處理和更詳細(xì)地分析波形，可以并行運(yùn)行多個(gè)DSP。以前在單獨(dú)的硬件項(xiàng)目中實(shí)現(xiàn)的許多功能可以包含在單個(gè)項(xiàng)目中。2.VT/CT監(jiān)測IfsuitableVTsareused,supervisionoftheVT/CTsuppliescanbemadea

31、vailable.VTsupervisionismademorecomplicatedbythedifferentconditionsunderwhichtheremaybenoVTsignal,someofwhichindicateVTfailureandsomeoccurbecauseapowersystemfaulthasoccurred.Ifonlyoneortwophasesarelost,theVTfailurealgorithmcanbeaccomplishedbydetectingresidualvoltagewithoutthepresenceofzeroornegative

32、phasesequencecurrent.Forlossofallthreephases,afaultinthesystemwouldbeaccompaniedbyachangeinthephasecurrents,soabsenceofsuchachangecanbetakenaslossoftheVTsignal.However,thistechniquefailswhenclosingontoadeadbuthealthyline,soaleveldetectorisalsorequiredtodistinguishbetweencurrentinrushduetolinechargin

33、gandthatduetoafault.如果使用合適的VT,可以對VT/CT電源進(jìn)行監(jiān)督。由于在不同的情況下可能沒有VT信號，VT監(jiān)控變得更加復(fù)雜，其中一些表示VT故障，另一些則是因?yàn)殡娏ο到y(tǒng)發(fā)生故障。如果只有一個(gè)或兩個(gè)相位丟失，VT故障算法可以通過檢測剩余電壓來實(shí)現(xiàn)，而不存在零序或負(fù)序電流。對于所有三相的損失，系統(tǒng)中的故障將伴隨著相電流的變化，因此，如果沒有這種變化，則可視為VT信號的損失。然而，這種技術(shù)在接近死線但正常的線路時(shí)失敗，因此還需要一個(gè)液位檢測器來區(qū)分由線路充電引起的電流涌流和由故障引起的電流涌流。CTsupervisioniscarriedoutmoreeasily.Thege

34、neralprincipleisthecalculationofalevelofnegativesequencecurrentthatisinconsistentwiththecalculatedvalueofnegativesequencevoltage.CT監(jiān)測更容易進(jìn)行。一般原則是計(jì)算與負(fù)序電壓計(jì)算值不一致的負(fù)序電流水平。2. CBControlandStateIndication/ConditionMonitoring3.CB控制和狀態(tài)指示/狀態(tài)監(jiān)測Systemoperatorsnormallyrequireknowledgeofthestateofallcircuitbreakers

35、undertheircontrol.TheCBposition-switchoutputscanbeconnectedtotherelaydigitalinputsandthereforeprovidetheindicationofstatethroughthecommunicationsbustoaremotecontrolcentre.Circuitbreakersalsorequireperiodicmaintenanceoftheiroperatingmechanismsandcontactstoensuretheyoperatewhenrequiredandthatthefaultc

36、apacityisnotaffectedadversely.Therequirementformaintenanceisafunctionofthenumberoftripoperations,thecumulativecurrentbrokenandthetypeofbreaker.Anumericalrelaycanrecordalloftheseparametersandhencebeconfiguredtosendanalarmwhenmaintenanceisdue.Ifmaintenanceisnotcarriedoutwithinapredefinedtimeornumberof

37、tripsaftermaintenanceisrequired,theCBcanbearrangedtotripandlockoutorinhibitcertainfunctionssuchasauto-reclose.系統(tǒng)操作員通常需要了解其控制下所有斷路器的狀態(tài)。CB位置開關(guān)輸出可連接至繼電器數(shù)字輸入，因此通過通信總線向遠(yuǎn)程控制中心提供狀態(tài)指示。斷路器還需要定期維護(hù)其操作機(jī)構(gòu)和觸點(diǎn)，以確保它們在需要時(shí)運(yùn)行，并且故障容量不會(huì)受到不利影響。維護(hù)要求是跳閘操作次數(shù)、累計(jì)斷開電流和斷路器類型的函數(shù)。數(shù)字繼電器可以記錄所有這些參數(shù)，因此可以配置為在維護(hù)到期時(shí)發(fā)送警報(bào)。如果在需要維護(hù)后，未在預(yù)定的時(shí)間

38、或跳閘次數(shù)內(nèi)進(jìn)行維護(hù)，可將CB設(shè)置為跳閘和鎖定或禁止某些功能，如自動(dòng)重合閘。Finally,aswellastrippingtheCBasrequiredunderfaultconditions,itcanalsobearrangedforadigitaloutputtobeusedforCBclosure,sothatseparateCBclosecontrolcircuitscanbeeliminated.最后,除了在故障條件下按要求跳閘CB外,還可以將其設(shè)置為用于CB閉合的數(shù)字輸出,以便消除單獨(dú)的CB閉合控制電路。3. DisturbanceRecorder(Oscillograph)干

39、擾記錄儀(示波器)Therelaymemoryrequiresacertainminimumnumberofcyclesofmeasureddatatobestoredforcorrectsignalprocessinganddetectionofevents.Thememorycaneasilybeexpandedtoallowstorageofagreatertimeperiodofinputdata,bothanalogueanddigital,ltthenhasthecapabilitytoactasadisturba

40、ncerecorderforthecircuitbeingmonitored,sothatbyfreezingthememoryattheinstantoffaultdetectionortrip,arecordofthedisturbanceisavailableforlaterdownloadandanalysis.Itmaybeinconvenienttodownloadtherecordimmediately,sofacilitiesmaybeprovidedtocaptureandstoreanumberofdisturbances.繼電器存儲(chǔ)器要求存儲(chǔ)一定數(shù)量的最小測量數(shù)據(jù)周期，以

41、進(jìn)行正確的信號處理和事件檢測。存儲(chǔ)器可以輕松擴(kuò)展，以允許存儲(chǔ)更長時(shí)間的輸入數(shù)據(jù)，包括模擬和數(shù)字?jǐn)?shù)據(jù)，以及繼電器輸出的狀態(tài)。info然后，它可以作為被監(jiān)測電路的干擾記錄器，這樣，通過在故障檢測或跳閘的瞬間凍結(jié)內(nèi)存，干擾記錄可供以后下載和分析。立即下載記錄可能不方便，因此可能會(huì)提供設(shè)施來捕獲和存儲(chǔ)一些干擾Inindustrialandsmalldistributionnetworks,thismaybeallthatisrequired.Intransmissionnetworks,itmaybenecessarytoprovideasinglerecordertomonitorseveralci

42、rcuitssimultaneously,andinthiscase,aseparatedisturbancerecorderisstillrequired.在工業(yè)和小型配電網(wǎng)絡(luò)中,這可能就是所需的全部。在傳輸網(wǎng)絡(luò)中,可能需要提供一個(gè)記錄器來同時(shí)監(jiān)測多個(gè)電路,在這種情況下,仍然需要一個(gè)單獨(dú)的干擾記錄器。2. TimeSynchronization5.時(shí)間同步Disturbancerecordsanddatarelatingtoenergyconsumptionrequirestimetaggingtoserveanyusefulpurpose.Althoughthereisaninternal

43、clock,thisisoflimitedaccuracyanduseofthisclocktoprovidetimeinformationmaycauseproblemsifthedisturbancerecordhastobecorrelatedwithsimilarrecordsfromothersourcestoobtainacompletepictureofanevent.Manynumericalrelayshavethefacilityfortimesynchronisationfromanexternalclock.ThestandardnormallyusedisanIRIG

44、-BorIEEE1588signal,whichmaybederivedfromseveralsourcesincludingaGPSsatellitereceiver.干擾記錄和與能源消耗相關(guān)的數(shù)據(jù)需要時(shí)間標(biāo)記，以達(dá)到任何有用的目的。雖然有一個(gè)內(nèi)部時(shí)鐘，但其精確度有限，如果干擾記錄必須與其他來源的類似記錄相關(guān)聯(lián)，以獲得事件的完整畫面，則使用該時(shí)鐘提供時(shí)間信息可能會(huì)導(dǎo)致問題。許多數(shù)字繼電器具有從外部時(shí)鐘同步時(shí)間的功能。通常使用的標(biāo)準(zhǔn)是IRIG-B或IEEE1588信號，該信號可能來自多個(gè)來源，包括GPS衛(wèi)星接收器。3. ProgrammableLogic6.可編程邏輯Logicfunction

45、sarewellsuitedtoimplementationusingmicroprocessors.Theimplementationoflogicinarelayisnotnew,asfunctionssuchasintertrippingandauto-recloserequireacertainamountoflogic.However,byprovidingasubstantialnumberofdigitalI/Oandmakingthelogiccapableofbeingprogrammedusingsuitableoff-linesoftware,thefunctionali

46、tyofsuchschemescanbeenhancedoradditionalfeaturesprovided.Forinstance,anovercurrentrelayatthereceivingendofatransformerfeedercouldusethetemperatureinputsprovidedtomonitortransformerwindingtemperatureandprovidealarmortripfacilitiestotheoperatororupstreamrelay,eliminatingtheneedforaseparatewindingtempe

47、raturerelay.Theremaybeotheradvantagessuchasdifferentlogicschemesrequiredbydifferentutilitiesthatnolongerneedseparaterelayversions,orsomehard-wiredlogictoimplement,andallofthesereducethecostofmanufacture.邏輯函數(shù)非常適合使用微處理器實(shí)現(xiàn)。繼電器中邏輯的實(shí)現(xiàn)并不新鮮，因?yàn)槁?lián)動(dòng)跳閘和自動(dòng)重合閘等功能需要一定數(shù)量的邏輯。然而，通過提供大量數(shù)字I/O并使邏輯能夠使用合適的離線軟件進(jìn)行編程，可以增強(qiáng)此類方

48、案的功能或提供附加功能。例如，變壓器饋線接收端的過電流繼電器可以使用提供的溫度輸入來監(jiān)測變壓器繞組溫度，并向操作員或上游繼電器提供報(bào)警或跳閘設(shè)施，從而無需單獨(dú)的繞組溫度繼電器。可能還有其他優(yōu)勢，例如不同的實(shí)用程序所需的不同邏輯方案，不再需要單獨(dú)的繼電器版本，或者一些硬接線邏輯來實(shí)現(xiàn)，所有這些都降低了制造成本。Itisalsoeasiertocustomizearelayforaspecificapplication,andeliminateotherdevicesthatwouldotherwiseberequired.為特定應(yīng)用定制繼電器也更容易,并消除其他需要的設(shè)備4. Provision

49、ofSettingGroups7.提供設(shè)置組Historically,electromechanicalandstaticrelayshavebeenprovidedwithfixedplugsettingsappliedtotherelay.Unfortunately,powersystemschangetheirtopologyduetooperationalreasonsonaregularbasis,suchassupplyfromnormaloremergencygeneration.Differentconfigurationsmayrequiredifferentrelayset

50、tingstomaintainthedesiredlevelofnetworkprotection.Faultlevelsaresignificantlydifferentonpartsofthenetworkthatareenergizedundernormalandemergencygeneration.Thisproblemcanbeovercomebytheprovisionwithintherelayofseveralsettinggroups,onlyoneofwhichisinuseatanyonetime.Changeoverbetweengroupscanbeachieved

51、fromaremotecommandfromtheoperator,orpossiblythroughtheprogrammablelogicsystem.Thismayobviatetheneedforduplicaterelaystobefittedwithsomeformofswitchingarrangementoftheinputsandoutputsdependingonnetworkcorfiguratior.Alsotheoperatorcanprogramtherelayremotelywithagroupofsettingsifrequired.從歷史上看，機(jī)電式和靜態(tài)繼電

52、器都配備了適用于繼電器的固定插頭設(shè)置。不幸的是，由于運(yùn)行原因，電力系統(tǒng)會(huì)定期改變其拓?fù)浣Y(jié)構(gòu)，例如正?；驊?yīng)急發(fā)電的供電。不同的配置可能需要不同的繼電器設(shè)置，以保持所需的網(wǎng)絡(luò)保護(hù)水平。在正常發(fā)電和緊急發(fā)電情況下通電的網(wǎng)絡(luò)部分，故障級別存在顯著差異。這個(gè)問題可以通過在繼電器內(nèi)提供多個(gè)設(shè)置組來解決，在任何時(shí)候，只有一個(gè)設(shè)置組在使用。可以通過操作員的遠(yuǎn)程命令，或可能通過可編程邏輯系統(tǒng)實(shí)現(xiàn)組之間的切換。這可以避免重復(fù)繼電器需要根據(jù)網(wǎng)絡(luò)配置配備某種形式的輸入和輸出開關(guān)安排。此外，如果需要，操作員還可以使用一組設(shè)置對繼電器進(jìn)行遠(yuǎn)程編程。Conclusions結(jié)論Theextrafacilitiesinnume

53、ricalrelaysmayavoidtheneedforothermeasurementandcontroldevicestobefittedinasubstation.Alsonumericalrelayshavefunctionalitythatpreviouslyrequiredseparateequipment.Theprotectionrelaynolongerperformsabasicprotectionfunctionbutisanintegralandmajorpartofasubstationautomationscheme.數(shù)字繼電器中的額外設(shè)施可以避免在變電站中安裝其

54、他測量和控制設(shè)備。此外，數(shù)字繼電器具有以前需要單獨(dú)設(shè)備的功能。保護(hù)繼電器不再執(zhí)行基本的保護(hù)功能，而是變電站自動(dòng)化方案的一個(gè)組成部分。Thechoiceofaprotectionrelayratherthansomeotherdeviceislogicalastheprotectionrelayisprobablytheonlydevicethatisvirtuallymandatoryoncircuitsofanysignificantrating.選擇保護(hù)繼電器而不是其他設(shè)備是合乎邏輯的,因?yàn)楸Ｗo(hù)繼電器可能是在任何重要額定值的電路上實(shí)際上必須使用的唯一設(shè)備。Thereforethefunct

55、ionspreviouslycarriedoutbyseparatedevicessuchasbaycontrollers,discretemeteringtransducersandsimilardevicesarenowfoundinaprotectionrelay.Itisnowpossibletoimplementasubstationautomationschemeusingnumericalrelaysasthemainhardwareprovidedatbaylevel.Asthepowerofmicroprocessorscontinuestogrowandpressureon

56、operatorstoreducecostscontinues,thistrendwillcontinue.OneobviousdevelopmentistheprovisionofRTUfacilitiesindesignatedrelaysthatactaslocalconcentratorsofinformationwithintheoverallnetworkautomationscheme.因此，以前由獨(dú)立設(shè)備（如間隔控制器、離散計(jì)量傳感器和類似設(shè)備）執(zhí)行的功能現(xiàn)在可以在保護(hù)繼電器中找到?，F(xiàn)在可以實(shí)施變電站自動(dòng)化方案，使用數(shù)字繼電器作為間隔層提供的主要硬件。隨著微處理器的功率持續(xù)增長

57、，運(yùn)營商降低成本的壓力持續(xù)，這一趨勢將繼續(xù)下去。一個(gè)明顯的發(fā)展是在指定的繼電器中提供RTU設(shè)施，作為整個(gè)網(wǎng)絡(luò)自動(dòng)化方案中的本地信息集中器。NumericalRelayConsiderations數(shù)字繼電器注意事項(xiàng)Theintroductionofnumericalrelaysreplacessomeoftheissuesofpreviousgenerationsofrelayswithnewones.Someofthenewissuesthatmustbeaddressedareasfollows:1. SoftwareversioncontrolRelaydatamanagement2. T

58、estingandcommissioning數(shù)字繼電器的引入用新的繼電器取代了前幾代繼電器的一些問題。必須解決的一些新問題如下：1. 軟件版本控制2. 中繼數(shù)據(jù)管理3.測試和調(diào)試SoftwareVersionControl1.軟件版本控制Numericalrelaysperformtheirfunctionsinsoftware.Theprocessusedforsoftwaregenerationisnodifferentinprincipletothatforanyotherdeviceusingreal-timesoftware,andincludesthedifficultiesofdevelopingcodethatiserror-free.數(shù)字繼電器在軟件中執(zhí)行其功能。用于軟件生成的過程在原則上與使用實(shí)時(shí)軟件的任何其他設(shè)備的過程沒有區(qū)別，并且