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1、1.Thecomplexityofaparticularmethodandthecorrespondingpay-offinperformancearetobedeterminedbythenatureofapplication.一个特殊方法的复杂性和相应的性能指标是由应用特性来决定2.However,adjustable-speeddrivesarealsobeingintroducedinnewapplicationareaswherespeedadjustmentisnotessentialbutoffersadvantages
2、inenergyconservationorproductivity在一些新的领域中也引入了调速驱动系统,但这里调速不是主要目的,而是为了从节约能源和提高生产力方面获益3・Toaccommodatethespecialcontrolsituationswhichariseperiodically,suchasprocessstart-up,shutdown,andmajormaintenanceeitherofprocessorcontrolequipmentandinstrumentation为了适应周期性出现的特殊控制状况,如进程
3、的启动,关机,过程的主体维修,控制设备和仪器的主体维修4.Changesarealwaysoccurring,andifactionsarenottaken,theimportantprocessvariables—thoserelatedtosafely,productquality,andproductionrates—willnotachievedesignconditions变化总是发生,如果不采取措施,那些有关安全,产品质量和生产效率的重要过程变量将不会达到设计条件的标准5・Anelectricprotectivedevic
4、eisaparticulartypeofequipmentappliedtoelectricpowersystemstodetectabnormalandintolerableconditionsandtoinitiateappropriatecorrectiveaction电气保护装置是一个特定类型的设备,被应用到电力系统当中,检测异常或不允许工作条件,以及采取适当的纠正措施的一种特定类型的设备6・Also,fromEq.(5-3A-6)wenotethataslongastheerrortermispresent,thecontr
5、ollerwillkeepchangingitsoutput,therebyintegratingtheerror,toremovetheerror从式(5-3A-6)中,我们注意到只要误差项存在,控制器就会不断改变其输出,从而通过对误差积分来消除误差7.Theelectricpowersubstationisanassemblyofequipmentinanelectricpowersystemthroughwhichelectricalenergyispassedfortransmission,distribution,inter
6、connection,transformation,conversion,orswitching电力配电站是设备是电力系统当中是设备的集合,通过这个电力系统电能被传输,分布,互连,变换•转换和开关形成的设备的集合8.Inthissectionanintroductiontothemostimportantaspectsofcontrolvalvesasappliedtoprocesscontrolispresented在本节当中控制阀门被应用于过程控制时,它的最重要的方面被提岀来了9.Atthisitisnecessarytodefi
7、nesometermsusedinthefieldofautomaticprocesscontrol此时定义一些自动过程控制领域中使用的术语是非常必要的10・Analternativeapproachofmodelingisthattheconverter-machinesystemcanbelinearizedaboutasteadystateoperatingpointusingthesmallsignalperturbationprinciple另一种建模方法是应用小信号扰动理论对逆变器•电机系统在稳态工作点附近进行线性化处理T
8、hedynamicsoftheacmachinedrivecontrolsystemisextremelyisextremelycomplexandthesubjectisreceivingwideattentionre