电气工程及其自动化专业英语

电气工程及其自动化专业英语Protectionrelay（继电保护）

Anewerdevelopmentintheofpowersystemprotectionistheofcomputers(usuallymicrocomputers)forrelaying（计算机继电保护）.Althoughcomputersprovidethesameprotectionasthatsupplied（供应）byconventional（常规）relays,therearesomeadvantagestotheuseofcomputer-basedrelaying.Thelogiccapability（逻辑能力）andapplicationexpansionpossibilities（应用的可扩展能力）forcomputer-basedrelayingismuchgreaterthanforelectromechanicaldevices（机电式继电保护装置）.Computer-basedrelayingsamplesthevalues（采样值）ofthecurrent,voltage,andotheritems（其他量）coveredintheprotectionscheme（在保护方案中）severaltimesasecond,andbyuseofA/Dconverters（转换器）,changetheseanalogvaluestodigitalformandthensendthemtothecomputer.Intheeventofafault（系统出现故障时）,thecomputercancalculatethefault’scurrentvaluesandcharacteristics（故障电流的值和特性）,andsettings（整定值）canbechangedmerelybyreprogramming（编程）.Computer-basedrelayingarealsocapable（有能力的）oflocatingfaults（故障的定位）,whichhasbeenoneofthemostpopularfeatures（最受欢迎的特征）intheirapplication.Inaddition,self-checkingfeaturescanbebuiltin（可配置自检功能）andsequenceofeventsinformation（事件顺序信息）canbedownloadedtoremote（遥远）computersforfastanalysis（快速分析）ofrelayingoperations.Computer-basedrelyingsystemconsistsofsubsystemswithwelldefinedfunctions（功能明确的子系统组成）.Althoughaspecificsubsystem（子系统）maybedifferentinsomeofitsdetails,thesesubsystemsaremostlikelytobeincorporatedinitsdesigninsomeform（以某种形式融合在设计中）.TheblockdiagraminFigure（框图）13-1showstheprincipalsubsystemsofacomputer-basedrelaying（微机继电保护的基本子系统的原理）.Theprocessor（处理器）isthecenterofitsorganization（整个组合）.Itisresponsible（主管，负责）fortheexecutionofrelayingprograms（继电保护程序的执行）,maintenanceofvarioustimingfunctions（各定时功能的保持）,andcommunicatingwithitsperipheralequipment（与外部设备的通讯）.Severaltypes（几种不同类型）ofmemories（存储器）areshowninFigure13-1─eachofthemservesaspecific（具体的）need.TheRandomAccessMemory（随机存取存储器）(RAM)holds（保持，储存）theinputsampledata（输入采样数据）astheyarebroughtinandprocessed（送入被处理过）.TheReadOnlyMemory（只读存储器）(ROM)orProgrammableReadOnlyMemory（可编程只读存储器）(PROM)isusedtostoretheprogramspermanently（永久性程序.）.Insomecases（在某些情况下）theprogramsmayexecute（执行）directly（直接）fromtheROMifitsreadtimeisshortenough.Ifthisisnotthecase（若不是这样）,theprogramsmustbecopiedfromtheROMintotheRAMduringaninitializationstage（在初始化阶段）,andthenthereal-timeexecution（实时执行）wouldtakeplacefromtheRAM.TheErasablePROM(EPROM)（可擦写电存储器）isneededforstoringcertainparameters（确定参数）(suchastherelayingsettings（继电器设定值）)whichmaybechangedfromtimetotime,butonceitissetitmustremainfixed（保持不变）evenifthepowersupply（供电）tothecomputerisinterrupted（中断）.Therelayinginputs（继电器的输入）arecurrentsandvoltages─or,toalesserextent（程度较轻）─digitalsignalsindicatingcontactstatus（指示触点状态的数字信号）.Theanalogsignalsmustbeconverted（转换）tovoltagesignalssuitableforconversion（适合于转换）todigitalform.Thecurrentandvoltagesignalsobtained（获得）fromcurrentandvoltagetransformersecondarywindings（变压器次级绕组）mustberestricted（限制到）toafullscalevalue（满额值）of±10volts.Thecurrentinputsmustbeconverted（转换）tovoltagesbyresistiveshunts（并联电阻）.Asthenormal（由于通常）currenttransformersecondarycurrents（电流互感器二次电流）maybeashundredsofamperes（数百千安）,shuntsofresistance（并联电阻）ofafewmilliohms（几毫欧姆）areneededtoproducethedesiredvoltage（所需的电压）forAnalogtoDigitalConverter（模拟数字转换器）(ADC).Analternative（另一种）arrangement（办法）wouldbetouseanauxiliarycurrenttransformer（辅助电流互感器）toreducethecurrenttolowerlevel.Anauxiliarycurrenttransformerserves（辅助电流互感器装置）anotherfunction:thatofprovidingelectricalisolation（电气隔离）betweentheminCTsecondary（电流互感器二次侧）andthecomputerinputsystem.（计算机输入系统）Sincethedigitalcomputercanbeprogrammedtoperformseveralfunctions（可编程来执行这些功能）aslongas（只要）ithastheinputandoutputsignalsneededforthosefunctions（提供各种功能所需要的输入和输出信号）.Itissimplemattertotherelayingcomputertodomanyothersubstationtasks（变电站的任务）,forexample,measuringandmonitoringflows（测量和监测潮流）andvoltagesintransformersandtransmissionlines（变压器和输电线路）,controllingtheopeningandclosingofcircuitbreakersandswitches（控制断路器和开关的分闸和合闸）,providingbackupforotherdevicesthathavefailed（对故障设备提供备用）,arefunctionsthatcanbetakenoverbytherelayingcomputer.

Therearemanyperceivedbenefits（显而易见的优点）ofadigitalrelayingsystem:1.Economics:withthesteadydecrease（逐渐下降）incostofdigitalhardware（数字型硬件）,coupledwiththeincreaseincostofconventionalrelaying（再加上传统继电器花费增加）.Itseemsreasonabletoassume（假想）thatcomputerrelayingisanattractivealternative.Softwaredevelopmentcostcanbeexpectedtobeevenedout（预期将被均衡化）byutilizingeconomiesofscale（规模化利用的经济体）inproducingmicroprocessorsdedicatedtobasicrelayingtasks（在致力于生产微处理器作为基本继电保护任务。）.2.Reliability（可靠性）:adigitalsystemiscontinuouslyactive（继续发展）providingahighlevelofaself-diagnosis（提供一个高水平自诊断）todetectaccidentalfailureswithinthedigitalrelayingsystem（以检测所述数字中继系统内的意外故障。）.3.Flexibility（灵活性）:revis