電氣工程及其自動化專業(yè)英語

電氣工程及其自動化專業(yè)英語Protectionrelay（繼電保護）

Anewerdevelopmentintheofpowersystemprotectionistheofcomputers(usuallymicrocomputers)forrelaying（計算機繼電保護）.Althoughcomputersprovidethesameprotectionasthatsupplied（供應）byconventional（常規(guī)）relays,therearesomeadvantagestotheuseofcomputer-basedrelaying.Thelogiccapability（邏輯能力）andapplicationexpansionpossibilities（應用的可擴展能力）forcomputer-basedrelayingismuchgreaterthanforelectromechanicaldevices（機電式繼電保護裝置）.Computer-basedrelayingsamplesthevalues（采樣值）ofthecurrent,voltage,andotheritems（其他量）coveredintheprotectionscheme（在保護方案中）severaltimesasecond,andbyuseofA/Dconverters（轉換器）,changetheseanalogvaluestodigitalformandthensendthemtothecomputer.Intheeventofafault（系統(tǒng)出現(xiàn)故障時）,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）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計中）.TheblockdiagraminFigure（框圖）13-1showstheprincipalsubsystemsofacomputer-basedrelaying（微機繼電保護的基本子系統(tǒng)的原理）.Theprocessor（處理器）isthecenterofitsorganization（整個組合）.Itisresponsible（主管，負責）fortheexecutionofrelayingprograms（繼電保護程序的執(zhí)行）,maintenanceofvarioustimingfunctions（各定時功能的保持）,andcommunicatingwithitsperipheralequipment（與外部設備的通訊）.Severaltypes（幾種不同類型）ofmemories（存儲器）areshowninFigure13-1─eachofthemservesaspecific（具體的）need.TheRandomAccessMemory（隨機存取存儲器）(RAM)holds（保持，儲存）theinputsampledata（輸入采樣數據）astheyarebroughtinandprocessed（送入被處理過）.TheReadOnlyMemory（只讀存儲器）(ROM)orProgrammableReadOnlyMemory（可編程只讀存儲器）(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（實時執(zhí)行）wouldtakeplacefromtheRAM.TheErasablePROM(EPROM)（可擦寫電存儲器）isneededforstoringcertainparameters（確定參數）(suchastherelayingsettings（繼電器設定值）)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（指示觸點狀態(tài)的數字信號）.Theanalogsignalsmustbeconverted（轉換）tovoltagesignalssuitableforconversion（適合于轉換）todigitalform.Thecurrentandvoltagesignalsobtained（獲得）fromcurrentandvoltagetransformersecondarywindings（變壓器次級繞組）mustberestricted（限制到）toafullscalevalue（滿額值）of±10volts.Thecurrentinputsmustbeconverted（轉換）tovoltagesbyresistiveshunts（并聯(lián)電阻）.Asthenormal（由于通常）currenttransformersecondarycurrents（電流互感器二次電流）maybeashundredsofamperes（數百千安）,shuntsofresistance（并聯(lián)電阻）ofafewmilliohms（幾毫歐姆）areneededtoproducethedesiredvoltage（所需的電壓）forAnalogtoDigitalConverter（模擬數字轉換器）(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）andthecomputerinputsystem.（計算機輸入系統(tǒng)）Sincethedigitalcomputercanbeprogrammedtoperformseveralfunctions（可編程來執(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）.Itissimplemattertotherelayingcomputertodomanyothersubstationtasks（變電站的任務）,forexample,measuringandmonitoringflows（測量和監(jiān)測潮流）andvoltagesintransformersandtransmissionlines（變壓器和輸電線路）,controllingtheopeningandclosingofcircuitbreakersandswitches（控制斷路器和開關的分閘和合閘）,providingbackupforotherdevicesthathavefailed（對故障設備提供備用）,arefunctionsthatcanbetakenoverbytherelayingcomputer.

Therearemanyperceivedbenefits（顯而易見的優(yōu)點）ofadigitalrelayingsystem:1.Economics:withthesteadydecrease（逐漸下降）incostofdigitalhardware（數字型硬件）,coupledwiththeincreaseincostofconventionalrelaying（再加上傳統(tǒng)繼電器花費增加）.Itseemsreasonabletoassume（假想）thatcomputerrelayingisanattractivealternative.Softwaredevelopmentcostcanbeexpectedtobeevenedout（預期將被均衡化）byutilizingeconomiesofscale（規(guī)模化利用的經濟體）inproducingmicroprocessorsdedicatedtobasicrelayingtasks（在致力于生產微處理器作為基本繼電保護任務。）.2.Reliability（可靠性）:adigitalsystemiscontinuouslyactive（繼續(xù)發(fā)展）providingahighlevelofaself-diagnosis（提供一個高水平自診斷）todetectaccidentalfailureswithinthedigitalrelayingsystem（以檢測所述數字中繼系統(tǒng)內的意外故障。）.3.Flexibility（靈活性）:revis