采暖通风空调系统中DDC控制和软件概述(英文)

1DDCControlsandSoftwarefortheHVACRDDCControlsandSoftwarefortheHVACLabAgenda1.TypesandLevelofAutomation2.HVACDDCControlPrinciples3.OpenProtocolControlPrinciples4.DDCArchitecture5.ExamplesofDDCSoftwarePrograms6.TypicalDDCControlSystemsandApplications7.PresentandFutureTrendsinDDCControls8.GettingDDCEquipmentinyourSchoolsDDCControlsQuiz1.TFDDCandPLC’sarebasicallythesamecontroldevices.2.TFThereare3keycomponentsofanyDDCcontrolssystem.3.TFBACNet,Lon,andTridiumareOpenSoftwareDDCIntegrationTools4.TFThethermistorislinearliketheRTD.5.TFTheBooleanPointisusedforconvertingtemperaturesensorsintousefulinformation.TheVariousLevelsofDDCandAutomation•ResidentialandHomeAutomation–SmartHomes,notwidelyadoptedwithHVACManufacturer’sEquipment–SmartHVACSystems,ie.Carrier,Nordyn•Commercial–DDCisDesignedforCommercialBuildings–MultipleVendors•Industrial–PLC’s,SCADA,LadderLogic,Costly$$$ResidentialandHomeAutomationCommercialDDCAutomationPresentDDCControlVendorsandMergerCorporationsSchneiderIndustrialAutomationEvolutionofControlsandDDCPCBasedDDCControlSystemFieldPanel1FieldPanel2FieldPanel3Trunk/NetworkCableLANDevicesLANDevicesModernDDCBuildingControlsUtilizeaFourLevelArchitectureSensorLevelFieldControllerLevelIntegrationLevelManagementLevelThePurposeofanyTemperatureControlSystem•Controlsystemsarethe“brains”ofHVACequipmenttomaintainhumancomfort.PicturedbelowisanAHUthatservesonlyonezone.ThistypeofAHUiscalledasinglezoneAHU.Intheexample,atemperaturesensor(stat)sendsasignaltoacontrolpanel,whichsendsasignaltoavalve.Three(3)KeyComponentsofanyControlSystemInclude:DDCTerminologySetPointandOffsetSetpointisthedesiredconditionofavariablethatistobemaintained,suchastemperature.Intheexamplebelow,75degreesF.istheroomtemperaturesetpoint.Offsetistheamountofdifferencebetweencontrolpointandsetpointinaproportionalcontrolsystem.Intheexamplebelow,theoffsetisapproximately4°F.DDCTerminologyControlPoint•TheControlPointistheactualtemperaturebeingsensed.TheControlPoint(temperature)maynotbeonthesetpoint,butinsteadmaybeaboveorbelowit.Simplystated,setpointiswhatyouwant,whilecontrolpointiswhatyouget.DDCTerminologyThrottlingRange•SystemThrottlingRange(STR)isthechangeinthemeasuredvariable(i.e.temperature)thatcausesthecontrolleddevicetotravelfromoneendofitsstroketotheother.•TwoPosition•FloatingAction•ProportionalAction•PI•PIDTheDDCControlCycleandControlActionCanbeVeryAccurateControlCycleGraphTwoPosition(OldSchool-NotAccurate)TwoPositioncontrolactionchart(heatingactionshown)FloatingActionControlFloatingControlActionProportionalActionProportionalControlActionProportionalwithIntegralControl(PI)ProportionalPlusIntegral(PI)ControlActionPID-ProportionalPlusIntegral&DerivativeProportionalPlusIntegralPlusDerivative(PID)controlaction•Boolean-Representsabinaryvaluewithonlytwostates,suchasOfforOn.•Numeric-Representsananalogvaluesuchasatemperature,level,rateorsimilarfloatingpointnumber,oravaryingcount(integer).•Enum-Representsanenumeratedstate(morethantwo),suchasamulti-speedfanwithstatesOff,Slow,andFast.Enumsareoftencalledmulti-statesordiscretes.•String-AstringofoneormoreASCIIcharactersandoften(ifalpha-numeric)withsomeliteralmeaning.FourTypesofPointDataCategoriesControlPointsfortheDDCSystem29EightTypesofControlPointsControlPointsfortheDDCBooleanNumericEnumeratedStringBooleanPoint•Areadonlypoint−Facets−ProxyExtension−OutNumericPoint•Areadonlypoint−Facets−ProxyExtension−OutEnumPoint•Areadonlypoint−Facets−ProxyExtension−OutStringPoint•Areadonlypoint−Facets−ProxyExtension−OutBooleanWritable•Extendedtoinclude−Prioritycontrols−Fallbackproperty−Overrideexpiration−7Commands−On&OfftimersNumericWritable•Extendedtoinclude−Prioritycontrols−Fallbackproperty−Overrideexpiration−5CommandsEnumWritable•Extendedtoinclude−Prioritycontrols−Fallbackproperty−Overrideexpiration−5CommandsStringWritable•Extendedtoinclude−Prioritycontrols−Fallbackproperty−Overrideexpiration−5CommandsSensors•Asensormonitorsandmeasuresavariable.TheHVACvariablesaretemperature,humidity,flow,andpressure.Differenttypesofsignalsareproducedbydifferenttypesofsensors.Theyinclude:–ElectricSensors–PneumaticSensors–ElectronicSensorsExamplesofasensorisshownhere.Whileitmayappeartobeathermostat,itisaremotesensorwitharemotesetpointdial.Thecontrollerisinanotherlocation.ElectronicSensorsInclude:•ResistancesensorsareResistanceTemperatureDevices(RTDs),andareusedinmeasuringtemperature.•Voltagesensorscouldbeusedfortemperature,humidityandpressure.•Currentsensorscouldbeusedfortemperature,humidity,andpressure.Thetypicalcurrentrangeis4to20mA(milliamps).TemperaturesSensorsCanbeeitherThermocouple,RTD,orThermistor.ThisChartComparestheAdvantagesandDisadvantages.ModernHVACDDCSensorsInclude•HumidityandTemperatureTransmitters•CO2forIndoorAirQuality(IAQ)UtilizingDemandVentilation•PowerMeters•BranchCircuitMonitors•EnergyMetersControllersCanInclude:ElectricControlsPneumaticControlsElectronicControlsDDCControlsControllersPrinciplesTheControllerReceivestheInputandProcessesanOutputTheDDCControllerHas3Functions1.ReceivestheInputFromtheSensor2.PerformsaLogicFunction3