第6章-Control-of-air-condition-systems

§6Controlandoptimizationofair-conditioningsystemsBuildingAutomationSystemLecturer:DouLiqianStructureofthecourse•6Controlandoptimizationofair-conditioningsystems6.1Introduction6.2Typicalcontrolloopsoftheair-conditioningprocess6.3ControlofCAVsystems6.4ControlofVAVsystems6.5Outdoorairventilationcontrolandoptimization6.6AnoverviewofoptimalcontrolmethodsusedforHVACsystems6.7Optimalcontrolofair-sidesystems6Controlandoptimizationofair-conditioningsystems6.1Introduction1introduction6.1Introduction1introduction6.1Introduction1introduction6.1Introduction1introduction6.1Introduction1introductionHeatpumpchillingHeating6.1Introduction1introductionductFanMotorDamperextractorfan6.1Introduction1introductionAirsideterminaldevice6.1Introduction1introductionAnair-conditioningsystemprovidesthecontrolledenvironmentinwhichthefollowingparametersaremaintainedwithindesiredranges:temperature,humidity,airdistributionandindoorairqualityinordertobuildupacomfortableandhealthyindoorenvironmentforpeopletoworkorlivein.Heatsourcedevice(heatpump,Furnace)Coldsourcedevice(compressor)AirsideterminaldeviceDuctFanMotorDamperSensorcontrollerextractorfanInletfan6.2TypicalcontrolloopsoftheA-Cprocess1introductionThischapterdiscussesthebasiccontrolloops,：controlofconstantairvolumesystems(CAV定风量系统控制)controlofvariableairvolumesystems(VAV变风量)controlofair-handlingandVAVboxesunits(AHU空气处理机组和变风量末端装置的控制)outdoorventilationcontrolandoptimization(新风通风控制和优化)theoptimalresetofsupplyairtemperatureandstaticpressureset-points（送分温度和静压设定值的优化重设）thesystematicoptimizationofair-conditioningsystems(空调系统在系统级的优化).Onlytheair-sidesystems空气侧系统areaddressedinthischapter.Structureofthecourse•6Controlandoptimizationofair-conditioningsystems6.1Introduction6.2Typicalcontrolloopsoftheair-conditioningprocess6.3ControlofCAVsystems6.4ControlofVAVsystems6.5Outdoorairventilationcontrolandoptimization6.6AnoverviewofoptimalcontrolmethodsusedforHVACsystems6.7Optimalcontrolofair-sidesystems6Controlandoptimizationofair-conditioningsystems6.2TypicalcontrolloopsoftheA-Cprocess1Typicalair-sidesystems(空气侧系统)6.2TypicalcontrolloopsoftheA-Cprocess1Typicalair-sidesystems(空气侧系统)Thetypesofair-sideair-conditioningsystemsinclude：all-airsystems（全空气系统）,air-watersystems（空气-水系统）,andall-watersystems（全水系统）.6.2TypicalcontrolloopsoftheA-Cprocess1Typicalair-sidesystems(空气侧系统)air-watersystems（空气-水系统）6.2TypicalcontrolloopsoftheA-Cprocess1Typicalair-sidesystems(空气侧系统)andall-watersystems（全水系统）.6.2TypicalcontrolloopsoftheA-Cprocess1Typicalair-sidesystems(空气侧系统)Regardingductworkdesign（风道设计）,thesesystemscanbefurtherdividedintosingle-duct（单风道）systemsanddual-duct（双风道）systems.6.2TypicalcontrolloopsoftheA-Cprocess1Typicalair-sidesystems(空气侧系统)dual-duct（双风道）systems.6.2TypicalcontrolloopsoftheA-Cprocess1Typicalair-sidesystems(空气侧系统)all-airsystemsTheadvantagesofareasfollows:•separationofmechanicalareasfromoccupants;•possibilityofusingoutdoorairforcoolingandrecovery;•flexibilitytooutdoorandoccupancychanges;•flexibilityindesignandcontrol;Thedisadvantagesare:•theyrequireadditionalductspace;•theairbalancerequiredcanbedifficult;•theyrequireclosecooperationbetweenarchitectural,systemandstruc-turaldesignerstoensureaccessibleterminaldevices.6.2TypicalcontrolloopsoftheA-Cprocess1Typicalair-sidesystems(空气侧系统)air-watersystemsFan-coilsystemsarethemostcommonlyusedair-watersystems.Afan-coilsystemissimpleindesign,operationandcontrol,anditislessexpensivethanall-airsystems.Itisflexibleforzoningandrequireslessspacefortheairductwork.However,thesystemismountedinoccupiedspaces,whichcancausenoiseproblems.Thereislittleflexibilityinoutdoorventilationcontrol,andfreecoolingisnotreallyachieved..2Cascadecontrol(串级系统)Cascadecontrolcanbeusedwhenthereareseveralmeasurementsignalsandonecontrolvariable.Itisparticularlyusefulwhentherearesignificantdynamics(e.g.longdeadtimesorlongtimeconstants)betweenthecontrolvariableandtheprocessvariable.Cascadecontrolcanbecategorizedintotwokinds.Oneiscalledbasiccascadecontrol,builtupbynestingthecontrolloopsasshownintheblockdiagram.Theotheriscalledreconfiguredcascadecontrol,whichistailoredforspecificapplications6.2TypicalcontrolloopsoftheA-Cprocess2Cascadecontrol(串级系统)6.2TypicalcontrolloopsoftheA-CprocessBasiccascadecontrolhastwoloops.Theinnerloopiscalledthesecondaryloop.Theouterloopiscalledtheprimaryloop.theouterloopdealswiththeprimarymeasuredsignal.Itisalsopossibletohaveacascadecontrolwithmorenestedloops.Theperformanceofasystemcanbeimprovedwithanumberofmeasuredsignals,uptoacertainlimit.Bydealingwiththefasterandslowprocesses(loops)inthecontrolsystemsseparately,thecontrollercompromisestheresponsespeedandcontrolstabilityandachievesquickerresponseandmorestablecontrolthanthatwhichcanbeachievedbyusingtheprocessvariabletomodulatethecontrolsignaldirectly.2Cascadecontrol(串级系统)6.2TypicalcontrolloopsoftheA-Cprocessbecauseoftheslowthermalresponsesofbuildings,ifspacetemperatureisuseddirectlyforVAVdampercontrol,seriouslyover-tunedordown-tunedphenomenacanbecomeobvious.Theset-pointofthedirectcontrolvariablewhichisnotpredefined,