装有变速执行器的DN

17电力能源•Power&Energy最近几年来，变速传动装置（VSD）在工业设备工程、甚至消费行业都日益得到广泛使用。其中一个主要的原因是该装置能够节能。Variable-speeddrives(VSD)haveincreasinglybecomeestablishedinindustrialplantengineeringandeventheconsumersectorinrecentyears.Oneofthemainreasonsfortheirselectionistheirpotentialtosaveenergy.Itis,forexample,cheaperforavariable-speedcompressortosupplytheflowofairrequired,insteadofrunningacompressoratafixedspeedformaximumdemandandgeneratingtheactualdemandbymeansofthrottles–thuswastingenergy.RunningadjustmentsbyvariablespeeddrivesreducesenergyconsumptionVariablespeeddrivescutcosts变速传动装置的运转调节降低了能耗Valves阀门变速传动装置削减成本装有变速执行器的DN1900、PN16蝶形阀，用于控制炼钢厂锅炉内的供气DN1800,PN16butterflyvalveswithvariablespeedactuatorforcontrolofairfeedinasteelplantfurnace18Power&Energy•电力能源例如，采用变速压缩机供应所需空气流比采用固定速度的压缩机更加便宜，因为后者针对满足最大的需求并使用节气阀控制产生实际需求，因此造成了能量的浪费。而推动VSD更加广泛地应用于工业进程的因素是执行结构元件与多种工艺要求之间的匹配。VSD在工业应用中的许多优势也可以在阀门市场和电力执行机构传动系统中得以实现。此外，还增添了许多新特性。AfurthermotivationfortheuseofVSDsinindustrialprocessesisthematchingofactuatorelementstodiverseprocessrequirements.ManyoftheadvantagesofferedbyVSDsinindustrialapplicationscanalsoberealisedonthevalvemarketandinelectricalactuatordrivesystems.Inaddition,newbenefitsarealsobeingadded.Therearedifferentwaysofrunningamotorwithvariablespeeds.Formainsvoltagesoflessthan1000Vandoutputsofseveral100kW,theso-called“frequencyconverterwithDCvoltagelink”isused,usuallyincombinationwitharobustinductionmotor.Therefore,onlythisversionwillbebrieflyoutlinedinthisarticle.ConvertingvoltageAvariable-speeddrive(VSD)requires3-phvoltageatthemotor,changeablebothintermsoffrequency(speed)andamplitude(voltageleveldeterminestorque).However,thevoltageprovidedbythemainssupplyisconstantintermsoffrequencyandamplitude.Theconversiontakesplaceintwosteps,rectifyingandsmoothing,andinversion.Inrectifyingandsmoothingthe1-phor3-phfeedvoltageisfirstconvertedintoaripple/wave-likeDCvoltageusinganetworkofrectifierdiodes(“bridgerectifiers”).Thevoltageisfurthersmoothedviathickcapacitorsthatareusedasabufferfortheenergy.Ininversion,thesecondpartofafrequencyconverterconsistsofsixfast“electronic”switchesconnectingtheDCvoltageinapreciselydefinedrhythmtothethreemotorterminals.Byswitchingveryquicklyandselectingthepropervoltage(pulse-widthmodulation),athree-phasevoltagesystemisestablished.ThelargeamountofDCvoltage“slices”arefilteredbythemotorwindings,onlythe“basicoscillation”ofthevoltagesgeneratesarotaryfieldwiththedesiredfrequencyandvoltageamplitude.The“trick”istoextrapolatethevoltagepatternsandtorapidlyimplementtheswitchingstates.InmodernVSDsthistaskisperformedbyhigh-speedprocessors(micro-processors使用SIPOS5Flash变速执行器操作的喷射冷却蒸汽减压阀SteamreducingvalveswithinjectioncoolingoperatedwithSIPOS5Flashvariablespeedactuator19电力能源•Power&Energy变速电动机有多种运行方式。对于干线电压低于1000V并且输出功率约为100kW左右的电动机，采用了所谓的“直流电压传输变频器”，并且通常与强健感应马达结合使用。因此，在本文中只简要介绍这种类型。变换电压变速传动装置（VSD）在电动机处需要三相电，并且频率（速度）和振幅（电压水平决定力矩）都应可调。但是，干线供电所提供电压的频率和振幅都是恒定的。变换包括两个步骤：整流和滤波，以及转换。在整流和滤波阶段，单相或三相馈电电压首先被转换为一种波纹/波状交流电压，用于整流二极管网络(“桥式整流器”)。接着电压使用厚电容器进行滤波，这些电容器用作能量的缓冲器。在转化阶段，变频器的第二部分包括六个快速“电子”开关，这些开关将具有精确定义脉动的直流电压连接至三个电动机终端。通过快速切换开关并选择适当的电压（脉冲宽度调制），就可以建立一个三相电压系统。大量的直流电压“削波”都被电动机绕组过滤，只有电压的“基本振荡”生成一个具有所需频率和电压振幅的旋转磁场。“窍门”在于外推电压起伏，并快速执行开关状态。在现代VSD中，该任务由高速处理器（微处理器或微控制器）执行。开关命令由电子元件执行，自二十世纪九十年代初期以来，电子元件就开始形成系列零件，确实达到了“理想开关”的要求，也就是达到了快速开关而没有损耗的程度：“IGBT”（绝缘栅双极晶体管）。以下对这些部件的容量进行介绍：在正常条件下，逆变器6个IGBT中的每一个都能以每秒6000到10000次的频率接通和断开约540V的电压（三相连接电压，整流400V）。在阀门应用中使用变速执行器的优点包括缓慢但稳定的启动。发电厂或水处理厂的阀门有时候必须承受很大的压差。当阀门在整个操作过程中快速工作时，就会产生湍流和涡流。这样，部件材料就受到应力作用，而这会危害到阀门、管路和连接零件。有害或破坏性的副作用（例如穴蚀和“水锤”）可能会扩散至整个设备，而这可以通过流量限制器良好“受控的”工作速度来防止。当阀门首次缓慢打开时，可能会出现压力补偿；当达到预定的阀门位置时，执行器可能会以更高的速度工作。ormicro-controllers).Theswitchingcommandsareimplementedbyelectroniccomponentswhichhavebeenavailableasserialpartssincethebeginningofthe1990sandvirtuallymeettherequirementsofan“idealswitch”,i.e.switchingrapidlyandwithoutloss:“IGBTs”(isolatedgatebipolartransistors).Justtogiveanideaofthecapacityofthesecomponents:undernormalconditions,eachofthe6IGBTsofaninvertertypicallyswitchesvoltagesofabout540V(three-phaselinkvoltageforrectifying400V)onandoffatafrequencyofapproximately6,000to10,000timespersecond.Theadvantagesofusingvariable-speedactuatorsinvalveapplicationsincludestartingupslowlybutconsistently.Valvesinpowerplantsorwatertreatmentplantssometimeshavetoresistmajordifferentialpressure.Whenoperatingthevalvequicklyovertheentiretravel,turbulencesandvorticesarecreated.Asaconsequence,stressisputonthematerialandthiscanrepresentahazardforvalve,pipeworkandconnectionparts.Undesiredordamagingside-effectssuchascavitationand“waterhammer”whichspreadwithintheentireplantcanbepreventedbyawell-“controlled”operationspeedoftheflowrestrictor.Whenfirstopeningthevalveslowly,pressurecompensationmaytakeplace;onreachingadefinedvalveposition,theactuatormaybeoperatedatincreasedspeed.Forvariable-speedmotors,themotorfrequencyisadaptedbymeansofaso-called“rampfunctiongenerator”withdefinedaccelerationandjoltlimitation(“ramp”).Iftheactuatormovesthevalveatfullspeedintothevalveseat,thefunction“closetightly”isfulfilled,butatthepriceofahighdynamic