電氣工程及其自動(dòng)化專(zhuān)業(yè)英語(yǔ)

電氣工程及其自動(dòng)化專(zhuān)業(yè)英語(yǔ)Protectionrelay（繼電保護(hù)）

Anewerdevelopmentintheofpowersystemprotectionistheofcomputers(usuallymicrocomputers)forrelaying（計(jì)算機(jī)繼電保護(hù)）.Althoughcomputersprovidethesameprotectionasthatsupplied（供應(yīng)）byconventional（常規(guī)）relays,therearesomeadvantagestotheuseofcomputer-basedrelaying.Thelogiccapability（邏輯能力）andapplicationexpansionpossibilities（應(yīng)用的可擴(kuò)展能力）forcomputer-basedrelayingismuchgreaterthanforelectromechanicaldevices（機(jī)電式繼電保護(hù)裝置）.Computer-basedrelayingsamplesthevalues（采樣值）ofthecurrent,voltage,andotheritems（其他量）coveredintheprotectionscheme（在保護(hù)方案中）severaltimesasecond,andbyuseofA/Dconverters（轉(zhuǎn)換器）,changetheseanalogvaluestodigitalformandthensendthemtothecomputer.Intheeventofafault（系統(tǒng)出現(xiàn)故障時(shí)）,thecomputercancalculatethefault’scurrentvaluesandcharacteristics（故障電流的值和特性）,andsettings（整定值）canbechangedmerelybyreprogramming（編程）.Computer-basedrelayingarealsocapable（有能力的）oflocatingfaults（故障的定位）,whichhasbeenoneofthemostpopularfeatures（最受歡迎的特征）intheirapplication.Inaddition,self-checkingfeaturescanbebuiltin（可配置自檢功能）andsequenceofeventsinformation（事件順序信息）canbedownloadedtoremote（遙遠(yuǎn)）computersforfastanalysis（快速分析）ofrelayingoperations.Computer-basedrelyingsystemconsistsofsubsystemswithwelldefinedfunctions（功能明確的子系統(tǒng)組成）.Althoughaspecificsubsystem（子系統(tǒng)）maybedifferentinsomeofitsdetails,thesesubsystemsaremostlikelytobeincorporatedinitsdesigninsomeform（以某種形式融合在設(shè)計(jì)中）.TheblockdiagraminFigure（框圖）13-1showstheprincipalsubsystemsofacomputer-basedrelaying（微機(jī)繼電保護(hù)的基本子系統(tǒng)的原理）.Theprocessor（處理器）isthecenterofitsorganization（整個(gè)組合）.Itisresponsible（主管，負(fù)責(zé)）fortheexecutionofrelayingprograms（繼電保護(hù)程序的執(zhí)行）,maintenanceofvarioustimingfunctions（各定時(shí)功能的保持）,andcommunicatingwithitsperipheralequipment（與外部設(shè)備的通訊）.Severaltypes（幾種不同類(lèi)型）ofmemories（存儲(chǔ)器）areshowninFigure13-1─eachofthemservesaspecific（具體的）need.TheRandomAccessMemory（隨機(jī)存取存儲(chǔ)器）(RAM)holds（保持，儲(chǔ)存）theinputsampledata（輸入采樣數(shù)據(jù)）astheyarebroughtinandprocessed（送入被處理過(guò)）.TheReadOnlyMemory（只讀存儲(chǔ)器）(ROM)orProgrammableReadOnlyMemory（可編程只讀存儲(chǔ)器）(PROM)isusedtostoretheprogramspermanently（永久性程序.）.Insomecases（在某些情況下）theprogramsmayexecute（執(zhí)行）directly（直接）fromtheROMifitsreadtimeisshortenough.Ifthisisnotthecase（若不是這樣）,theprogramsmustbecopiedfromtheROMintotheRAMduringaninitializationstage（在初始化階段）,andthenthereal-timeexecution（實(shí)時(shí)執(zhí)行）wouldtakeplacefromtheRAM.TheErasablePROM(EPROM)（可擦寫(xiě)電存儲(chǔ)器）isneededforstoringcertainparameters（確定參數(shù)）(suchastherelayingsettings（繼電器設(shè)定值）)whichmaybechangedfromtimetotime,butonceitissetitmustremainfixed（保持不變）evenifthepowersupply（供電）tothecomputerisinterrupted（中斷）.Therelayinginputs（繼電器的輸入）arecurrentsandvoltages─or,toalesserextent（程度較輕）─digitalsignalsindicatingcontactstatus（指示觸點(diǎn)狀態(tài)的數(shù)字信號(hào)）.Theanalogsignalsmustbeconverted（轉(zhuǎn)換）tovoltagesignalssuitableforconversion（適合于轉(zhuǎn)換）todigitalform.Thecurrentandvoltagesignalsobtained（獲得）fromcurrentandvoltagetransformersecondarywindings（變壓器次級(jí)繞組）mustberestricted（限制到）toafullscalevalue（滿額值）of±10volts.Thecurrentinputsmustbeconverted（轉(zhuǎn)換）tovoltagesbyresistiveshunts（并聯(lián)電阻）.Asthenormal（由于通常）currenttransformersecondarycurrents（電流互感器二次電流）maybeashundredsofamperes（數(shù)百千安）,shuntsofresistance（并聯(lián)電阻）ofafewmilliohms（幾毫歐姆）areneededtoproducethedesiredvoltage（所需的電壓）forAnalogtoDigitalConverter（模擬數(shù)字轉(zhuǎn)換器）(ADC).Analternative（另一種）arrangement（辦法）wouldbetouseanauxiliarycurrenttransformer（輔助電流互感器）toreducethecurrenttolowerlevel.Anauxiliarycurrenttransformerserves（輔助電流互感器裝置）anotherfunction:thatofprovidingelectricalisolation（電氣隔離）betweentheminCTsecondary（電流互感器二次側(cè)）andthecomputerinputsystem.（計(jì)算機(jī)輸入系統(tǒng)）Sincethedigitalcomputercanbeprogrammedtoperformseveralfunctions（可編程來(lái)執(zhí)行這些功能）aslongas（只要）ithastheinputandoutputsignalsneededforthosefunctions（提供各種功能所需要的輸入和輸出信號(hào)）.Itissimplemattertotherelayingcomputertodomanyothersubstationtasks（變電站的任務(wù)）,forexample,measuringandmonitoringflows（測(cè)量和監(jiān)測(cè)潮流）andvoltagesintransformersandtransmissionlines（變壓器和輸電線路）,controllingtheopeningandclosingofcircuitbreakersandswitches（控制斷路器和開(kāi)關(guān)的分閘和合閘）,providingbackupforotherdevicesthathavefailed（對(duì)故障設(shè)備提供備用）,arefunctionsthatcanbetakenoverbytherelayingcomputer.

Therearemanyperceivedbenefits（顯而易見(jiàn)的優(yōu)點(diǎn)）ofadigitalrelayingsystem:1.Economics:withthesteadydecrease（逐漸下降）incostofdigitalhardware（數(shù)字型硬件）,coupledwiththeincreaseincostofconventionalrelaying（再加上傳統(tǒng)繼電器花費(fèi)增加）.Itseemsreasonabletoassume（假想）thatcomputerrelayingisanattractivealternative.Softwaredevelopmentcostcanbeexpectedtobeevenedout（預(yù)期將被均衡化）byutilizingeconomiesofscale（規(guī)模化利用的經(jīng)濟(jì)體）inproducingmicroprocessorsdedicatedtobasicrelayingtasks（在致力于生產(chǎn)微處理器作為基本繼電保護(hù)任務(wù)。）.2.Reliability（可靠性）:adigitalsystemiscontinuouslyactive（繼續(xù)發(fā)展）providingahighlevelofaself-diagnosis（提供一個(gè)高水平自診斷）todetectaccidentalfailureswithinthedigitalrelayingsystem（以檢測(cè)所述數(shù)字中繼系統(tǒng)內(nèi)的意外故障。）.3.Flexibility（靈活性）:revis