Buildings.Applications.DataCenters.ChillerCooled.Controls

Package with control components for Buildings.Applications.DataCenters.ChillerCooled.Examples

Information

Collection of models for the control of chilled water system with waterside economizer.

Extends from Modelica.Icons.Package (Icon for standard packages).

Package Content

Name Description
Buildings.Applications.DataCenters.ChillerCooled.Controls.ChillerStage ChillerStage Chiller staging control logic
Buildings.Applications.DataCenters.ChillerCooled.Controls.ConstantSpeedPumpStage ConstantSpeedPumpStage Staging control for constant speed pumps
Buildings.Applications.DataCenters.ChillerCooled.Controls.CoolingMode CoolingMode Mode controller for integrated waterside economizer and chiller
Buildings.Applications.DataCenters.ChillerCooled.Controls.CoolingModeNonIntegrated CoolingModeNonIntegrated Cooling mode controller in the chilled water system with a non-integrated waterside economizer
Buildings.Applications.DataCenters.ChillerCooled.Controls.CoolingTowerSpeed CoolingTowerSpeed Controller for the fan speed in cooling towers
Buildings.Applications.DataCenters.ChillerCooled.Controls.Reheat Reheat Model that implements an on and off controller for a reheater
Buildings.Applications.DataCenters.ChillerCooled.Controls.VariableSpeedPumpStage VariableSpeedPumpStage Staging control for variable speed pumps
Buildings.Applications.DataCenters.ChillerCooled.Controls.Validation Validation Collection of validation models

Buildings.Applications.DataCenters.ChillerCooled.Controls.ChillerStage Buildings.Applications.DataCenters.ChillerCooled.Controls.ChillerStage

Chiller staging control logic

Buildings.Applications.DataCenters.ChillerCooled.Controls.ChillerStage

Information

This is a chiller staging control that works as follows:

Extends from Modelica.Blocks.Icons.Block (Basic graphical layout of input/output block).

Parameters

TypeNameDefaultDescription
TimetWai Waiting time [s]
PowerQEva_nominal Nominal cooling capaciaty(Negative means cooling) [W]
PowercriPoiLoa0.55*QEva_nominalCritical point of cooling load for switching one chiller on or off [W]
PowerdQ0.25*QEva_nominalDeadband for critical point of cooling load [W]
TemperaturecriPoiTem279.15Critical point of temperature for switching one chiller on or off [K]
TemperatureDifferencedT1Deadband width for critical point of switching temperature [K]

Connectors

TypeNameDescription
input IntegerInputcooModCooling mode signal, integer value of Buildings.Applications.DataCenters.Types.CoolingMode
input RealInputQTotTotal cooling load in the chillers, negative
output RealOutputy[2]On/off signal for the chillers - 0: off; 1: on
input RealInputTCHWSupTemperature of leaving chilled water [K]

Modelica definition

model ChillerStage "Chiller staging control logic" extends Modelica.Blocks.Icons.Block; parameter Modelica.SIunits.Time tWai "Waiting time"; parameter Modelica.SIunits.Power QEva_nominal "Nominal cooling capaciaty(Negative means cooling)"; parameter Modelica.SIunits.Power criPoiLoa=0.55*QEva_nominal "Critical point of cooling load for switching one chiller on or off"; parameter Modelica.SIunits.Power dQ=0.25*QEva_nominal "Deadband for critical point of cooling load"; parameter Modelica.SIunits.Temperature criPoiTem=279.15 "Critical point of temperature for switching one chiller on or off"; parameter Modelica.SIunits.TemperatureDifference dT=1 "Deadband width for critical point of switching temperature"; Modelica.Blocks.Interfaces.IntegerInput cooMod "Cooling mode signal, integer value of Buildings.Applications.DataCenters.Types.CoolingMode"; Modelica.Blocks.Interfaces.RealInput QTot "Total cooling load in the chillers, negative"; Modelica.Blocks.Interfaces.RealOutput y[2] "On/off signal for the chillers - 0: off; 1: on"; Modelica.Blocks.Interfaces.RealInput TCHWSup( final quantity="ThermodynamicTemperature", final unit="K", displayUnit="degC") "Temperature of leaving chilled water "; Modelica.StateGraph.Transition con1( enableTimer=true, waitTime=tWai, condition=cooMod > Integer(Buildings.Applications.DataCenters.Types.CoolingModes.FreeCooling)) "Fire condition 1: free cooling to partially mechanical cooling"; Modelica.StateGraph.StepWithSignal oneOn(nIn=2, nOut=2) "One chiller is commanded on"; Modelica.StateGraph.InitialStep off(nIn=1) "Free cooling mode"; Modelica.StateGraph.StepWithSignal twoOn "Two chillers are commanded on"; Modelica.StateGraph.Transition con2( enableTimer=true, waitTime=tWai, condition=cooMod == Integer(Buildings.Applications.DataCenters.Types.CoolingModes.FullMechanical) and (-QTot > -(criPoiLoa + dQ) or TCHWSup > criPoiTem + dT)) "Fire condition 2: partially mechanical cooling to fully mechanical cooling"; Modelica.StateGraph.Transition con3( enableTimer=true, waitTime=tWai, condition=(-QTot < -(criPoiLoa - dQ) or TCHWSup < criPoiTem - dT)) "Fire condition 3: fully mechanical cooling to partially mechanical cooling"; Modelica.StateGraph.Transition con4( enableTimer=true, waitTime=tWai, condition=cooMod == Integer(Buildings.Applications.DataCenters.Types.CoolingModes.FreeCooling)) "Fire condition 4: partially mechanical cooling to free cooling"; inner Modelica.StateGraph.StateGraphRoot stateGraphRoot; Modelica.Blocks.Tables.CombiTable1Ds combiTable1Ds(table=[0, 0, 0; 1, 1, 0; 2, 1, 1]); Buildings.Controls.OBC.CDL.Conversions.BooleanToInteger booToInt(final integerTrue=1, final integerFalse=0); Buildings.Controls.OBC.CDL.Conversions.BooleanToInteger booToInt1(final integerFalse=0, final integerTrue=2); Buildings.Controls.OBC.CDL.Integers.Add addInt; Buildings.Controls.OBC.CDL.Conversions.IntegerToReal intToRea; equation connect(off.outPort[1], con1.inPort); connect(con1.outPort, oneOn.inPort[1]); connect(con2.inPort, oneOn.outPort[1]); connect(con2.outPort, twoOn.inPort[1]); connect(twoOn.outPort[1], con3.inPort); connect(con4.outPort, off.inPort[1]); connect(con3.outPort, oneOn.inPort[2]); connect(con4.inPort, oneOn.outPort[2]); connect(combiTable1Ds.y, y); connect(twoOn.active, booToInt1.u); connect(oneOn.active, booToInt.u); connect(booToInt.y, addInt.u1); connect(booToInt1.y, addInt.u2); connect(addInt.y, intToRea.u); connect(intToRea.y, combiTable1Ds.u); end ChillerStage;

Buildings.Applications.DataCenters.ChillerCooled.Controls.ConstantSpeedPumpStage Buildings.Applications.DataCenters.ChillerCooled.Controls.ConstantSpeedPumpStage

Staging control for constant speed pumps

Buildings.Applications.DataCenters.ChillerCooled.Controls.ConstantSpeedPumpStage

Information

This model describes a simple staging control for two constant-speed pumps in a chilled water plant with two chillers and a waterside economizer (WSE). The staging sequence is shown as below.

Extends from Modelica.Blocks.Icons.Block (Basic graphical layout of input/output block).

Parameters

TypeNameDefaultDescription
TimetWai Waiting time [s]

Connectors

TypeNameDescription
input IntegerInputcooModCooling mode - 0:off, 1: free cooling mode; 2: partially mechanical cooling; 3: fully mechanical cooling
input IntegerInputnumOnChiThe number of running chillers
output RealOutputy[2]On/off signal - 0: off; 1: on

Modelica definition

model ConstantSpeedPumpStage "Staging control for constant speed pumps" extends Modelica.Blocks.Icons.Block; parameter Modelica.SIunits.Time tWai "Waiting time"; Modelica.Blocks.Interfaces.IntegerInput cooMod "Cooling mode - 0:off, 1: free cooling mode; 2: partially mechanical cooling; 3: fully mechanical cooling"; Modelica.Blocks.Interfaces.IntegerInput numOnChi "The number of running chillers"; Modelica.Blocks.Interfaces.RealOutput y[2] "On/off signal - 0: off; 1: on"; Modelica.StateGraph.Transition con1( enableTimer=true, waitTime=tWai, condition=cooMod == Integer(Buildings.Applications.DataCenters.Types.CoolingModes.FreeCooling) or cooMod == Integer(Buildings.Applications.DataCenters.Types.CoolingModes.PartialMechanical) or cooMod == Integer(Buildings.Applications.DataCenters.Types.CoolingModes.FullMechanical)) "Fire condition 1: free cooling to partially mechanical cooling"; Modelica.StateGraph.StepWithSignal oneOn(nIn=2, nOut=2) "One chiller is commanded on"; Modelica.StateGraph.InitialStep off(nIn=1) "Free cooling mode"; Modelica.StateGraph.StepWithSignal twoOn "Two chillers are commanded on"; Modelica.StateGraph.Transition con2( enableTimer=true, waitTime=tWai, condition=cooMod == Integer(Buildings.Applications.DataCenters.Types.CoolingModes.FreeCooling) or cooMod == Integer(Buildings.Applications.DataCenters.Types.CoolingModes.PartialMechanical) or (cooMod == Integer(Buildings.Applications.DataCenters.Types.CoolingModes.FullMechanical) and numOnChi > 1)) "Fire condition 2: partially mechanical cooling to fully mechanical cooling"; Modelica.StateGraph.Transition con3( enableTimer=true, waitTime=tWai, condition=cooMod == Integer(Buildings.Applications.DataCenters.Types.CoolingModes.FullMechanical) and numOnChi < 2) "Fire condition 3: fully mechanical cooling to partially mechanical cooling"; Modelica.StateGraph.Transition con4( enableTimer=true, waitTime=tWai, condition=cooMod == Integer(Buildings.Applications.DataCenters.Types.CoolingModes.FreeCooling)) "Fire condition 4: partially mechanical cooling to free cooling"; inner Modelica.StateGraph.StateGraphRoot stateGraphRoot; Modelica.Blocks.Tables.CombiTable1Ds combiTable1Ds(table=[0, 0, 0; 1, 1, 0; 2, 1, 1]); Buildings.Controls.OBC.CDL.Conversions.BooleanToInteger booToInt(final integerTrue=1, final integerFalse=0); Buildings.Controls.OBC.CDL.Conversions.BooleanToInteger booToInt1(final integerFalse=0, final integerTrue=2); Buildings.Controls.OBC.CDL.Integers.Add addInt; Buildings.Controls.OBC.CDL.Conversions.IntegerToReal intToRea; equation connect(off.outPort[1], con1.inPort); connect(con1.outPort, oneOn.inPort[1]); connect(con2.inPort, oneOn.outPort[1]); connect(con2.outPort, twoOn.inPort[1]); connect(twoOn.outPort[1], con3.inPort); connect(con4.outPort, off.inPort[1]); connect(con3.outPort, oneOn.inPort[2]); connect(con4.inPort, oneOn.outPort[2]); connect(combiTable1Ds.y, y); connect(oneOn.active, booToInt.u); connect(twoOn.active, booToInt1.u); connect(booToInt.y, addInt.u1); connect(booToInt1.y, addInt.u2); connect(intToRea.y, combiTable1Ds.u); connect(addInt.y, intToRea.u); end ConstantSpeedPumpStage;

Buildings.Applications.DataCenters.ChillerCooled.Controls.CoolingMode Buildings.Applications.DataCenters.ChillerCooled.Controls.CoolingMode

Mode controller for integrated waterside economizer and chiller

Buildings.Applications.DataCenters.ChillerCooled.Controls.CoolingMode

Information

Controller that outputs if the chilled water system is in Free Cooling (FC) mode, Partially Mechanical Cooling (PMC) mode or Fully Mechanical Cooling (FMC) mode.

The waterside economizer is enabled when

  1. The waterside economizer has been disabled for at least 20 minutes, and
  2. TCHWR > TWetBul + TTowApp + deaBan1

The waterside economizer is disabled when

  1. The waterside economizer has been enabled for at least 20 minutes, and
  2. TWSE_CHWST > TWSE_CHWRT - deaBan2

The chiller is enabled when

  1. The chiller has been disabled for at leat 20 minutes, and
  2. TWSE_CHWST > TCHWSTSet + deaBan3

The chiller is disabled when

  1. The chiller has been enabled for at leat 20 minutes, and
  2. TWSE_CHWST ≤ TCHWSTSet + deaBan4

where TWSE_CHWST is the chilled water supply temperature for the WSE, TWetBul is the wet bulb temperature, TTowApp is the cooling tower approach, TWSE_CHWRT is the chilled water return temperature for the WSE, and TCHWSTSet is the chilled water supply temperature setpoint for the system. deaBan 1-4 are deadbands for each switching point.

References

Extends from Modelica.Blocks.Icons.Block (Basic graphical layout of input/output block).

Parameters

TypeNameDefaultDescription
TimetWai Waiting time [s]
TemperatureDifferencedeaBan1 Dead band width 1 for switching chiller on [K]
TemperatureDifferencedeaBan2 Dead band width 2 for switching waterside economizer off [K]
TemperatureDifferencedeaBan3 Dead band width 3 for switching waterside economizer on [K]
TemperatureDifferencedeaBan4 Dead band width 4 for switching chiller off [K]

Connectors

TypeNameDescription
input RealInputTCHWRetWSETemperature of entering chilled water that flows to waterside economizer [K]
input RealInputTCHWSupWSETemperature of leaving chilled water that flows out from waterside economizer [K]
input RealInputTCHWSupSetSupply chilled water temperature setpoint [K]
input RealInputTAppApproach temperature in the cooling tower [K]
output IntegerOutputyCooling mode signal, integer value of Buildings.Applications.DataCenters.Types.CoolingMode
input RealInputTWetBulWet bulb temperature of outdoor air [K]

Modelica definition

model CoolingMode "Mode controller for integrated waterside economizer and chiller" extends Modelica.Blocks.Icons.Block; parameter Modelica.SIunits.Time tWai "Waiting time"; parameter Modelica.SIunits.TemperatureDifference deaBan1 "Dead band width 1 for switching chiller on "; parameter Modelica.SIunits.TemperatureDifference deaBan2 "Dead band width 2 for switching waterside economizer off"; parameter Modelica.SIunits.TemperatureDifference deaBan3 "Dead band width 3 for switching waterside economizer on "; parameter Modelica.SIunits.TemperatureDifference deaBan4 "Dead band width 4 for switching chiller off"; Modelica.Blocks.Interfaces.RealInput TCHWRetWSE( final quantity="ThermodynamicTemperature", final unit="K", displayUnit="degC") "Temperature of entering chilled water that flows to waterside economizer "; Modelica.Blocks.Interfaces.RealInput TCHWSupWSE( final quantity="ThermodynamicTemperature", final unit="K", displayUnit="degC") "Temperature of leaving chilled water that flows out from waterside economizer"; Modelica.Blocks.Interfaces.RealInput TCHWSupSet( final quantity="ThermodynamicTemperature", final unit="K", displayUnit="degC") "Supply chilled water temperature setpoint "; Modelica.Blocks.Interfaces.RealInput TApp( final quantity="TemperatureDifference", final unit="K", displayUnit="degC") "Approach temperature in the cooling tower"; Modelica.Blocks.Interfaces.IntegerOutput y "Cooling mode signal, integer value of Buildings.Applications.DataCenters.Types.CoolingMode"; Modelica.StateGraph.Transition con1( enableTimer=true, waitTime=tWai, condition=TCHWSupWSE > TCHWSupSet + deaBan1) "Fire condition 1: free cooling to partially mechanical cooling"; Modelica.StateGraph.StepWithSignal parMecCoo(nIn=2, nOut=2) "Partial mechanical cooling mode"; Modelica.StateGraph.InitialStepWithSignal freCoo(nIn=1) "Free cooling mode"; Modelica.StateGraph.StepWithSignal fulMecCoo "Fully mechanical cooling mode"; Modelica.StateGraph.Transition con2( enableTimer=true, waitTime=tWai, condition=TCHWRetWSE < TCHWSupWSE + deaBan2) "Fire condition 2: partially mechanical cooling to fully mechanical cooling"; Modelica.StateGraph.Transition con3( enableTimer=true, waitTime=tWai, condition=TCHWRetWSE > TWetBul + TApp + deaBan3) "Fire condition 3: fully mechanical cooling to partially mechanical cooling"; Modelica.StateGraph.Transition con4( enableTimer=true, waitTime=tWai, condition=TCHWSupWSE <= TCHWSupSet + deaBan4) "Fire condition 4: partially mechanical cooling to free cooling"; inner Modelica.StateGraph.StateGraphRoot stateGraphRoot; Modelica.Blocks.Interfaces.RealInput TWetBul( final quantity="ThermodynamicTemperature", final unit="K", displayUnit="degC") "Wet bulb temperature of outdoor air"; Modelica.Blocks.MathInteger.MultiSwitch swi( y_default=0, nu=3, expr={Integer(Buildings.Applications.DataCenters.Types.CoolingModes.FreeCooling), Integer(Buildings.Applications.DataCenters.Types.CoolingModes.PartialMechanical), Integer(Buildings.Applications.DataCenters.Types.CoolingModes.FullMechanical)}) "Switch boolean signals to real signal"; equation connect(freCoo.outPort[1], con1.inPort); connect(con1.outPort, parMecCoo.inPort[1]); connect(con2.inPort, parMecCoo.outPort[1]); connect(con2.outPort, fulMecCoo.inPort[1]); connect(fulMecCoo.outPort[1], con3.inPort); connect(con4.outPort, freCoo.inPort[1]); connect(con3.outPort, parMecCoo.inPort[2]); connect(con4.inPort, parMecCoo.outPort[2]); connect(swi.y, y); connect(freCoo.active, swi.u[1]); connect(parMecCoo.active, swi.u[2]); connect(fulMecCoo.active, swi.u[3]); end CoolingMode;

Buildings.Applications.DataCenters.ChillerCooled.Controls.CoolingModeNonIntegrated Buildings.Applications.DataCenters.ChillerCooled.Controls.CoolingModeNonIntegrated

Cooling mode controller in the chilled water system with a non-integrated waterside economizer

Buildings.Applications.DataCenters.ChillerCooled.Controls.CoolingModeNonIntegrated

Information

Chilled water plant with a non-integrated waterside economizer (WSE) have two cooling modes: free cooling (FC) mode and fully mechanical cooling (FMC) mode. This model determines when to activate FC or FMC for a chilled water system with 2 chillers and 1 waterside economizer.

The FMC mode is activated when

and the FC mode is activated when

where TWetBulb is the wet bulb temperature of the outdoor air, TWetBulb,tran is the wet bulb temperature transition point for switching between FC and FMC, TCHWST is the chilled water supply temperature, TCHWSTSet is the chilled water supply temperature setpoint,and numOnChi is the number of running chillers.

Extends from Modelica.Blocks.Icons.Block (Basic graphical layout of input/output block).

Parameters

TypeNameDefaultDescription
TemperatureDifferencedeaBan Dead band width for switching waterside economizer off [K]
TemperatureTSwi Temperature transition to free cooling mode [K]
TimetWai Waiting time [s]

Connectors

TypeNameDescription
input IntegerInputnumOnChiNumber of running chillers
input RealInputTWetBulWet bulb temperature of outdoor air [K]
input RealInputTCHWSupTemperature of leaving chilled water [K]
input RealInputTCHWSupSetTemperature setpoint of leaving chilled water [K]
output IntegerOutputyCooling mode signal (1: free cooling mode, 3: fully mechanical cooling)

Modelica definition

model CoolingModeNonIntegrated "Cooling mode controller in the chilled water system with a non-integrated waterside economizer" extends Modelica.Blocks.Icons.Block; parameter Modelica.SIunits.TemperatureDifference deaBan "Dead band width for switching waterside economizer off "; parameter Modelica.SIunits.Temperature TSwi "Temperature transition to free cooling mode"; parameter Modelica.SIunits.Time tWai "Waiting time"; Modelica.Blocks.Interfaces.IntegerInput numOnChi "Number of running chillers"; Modelica.Blocks.Interfaces.RealInput TWetBul( final quantity="ThermodynamicTemperature", final unit="K", displayUnit="degC") "Wet bulb temperature of outdoor air"; Modelica.Blocks.Interfaces.RealInput TCHWSup( final quantity="ThermodynamicTemperature", final unit="K", displayUnit="degC") "Temperature of leaving chilled water "; Modelica.Blocks.Interfaces.RealInput TCHWSupSet( final quantity="ThermodynamicTemperature", final unit="K", displayUnit="degC") "Temperature setpoint of leaving chilled water "; Modelica.Blocks.Interfaces.IntegerOutput y "Cooling mode signal (1: free cooling mode, 3: fully mechanical cooling)"; Modelica.StateGraph.InitialStepWithSignal freCoo(nIn=1) "Free cooling mode"; Modelica.StateGraph.StepWithSignal fulMecCoo "Fully mechanical cooling mode"; Modelica.StateGraph.Transition con1( enableTimer=true, waitTime=tWai, condition=TWetBul > TSwi + deaBan or TCHWSup > TCHWSupSet + deaBan) "Fire condition 1: free cooling to fully mechanical cooling"; Modelica.Blocks.MathInteger.MultiSwitch swi( nu=2, y_default=0, expr={Integer(Buildings.Applications.DataCenters.Types.CoolingModes.FreeCooling), Integer(Buildings.Applications.DataCenters.Types.CoolingModes.FullMechanical)}) "Switch boolean signals to real signal"; Modelica.StateGraph.Transition con2( enableTimer=true, waitTime=tWai, condition=TWetBul <= TSwi - deaBan and numOnChi == 1) "Fire condition 2: fully mechanical cooling to free cooling"; inner Modelica.StateGraph.StateGraphRoot stateGraphRoot; equation connect(freCoo.outPort[1], con1.inPort); connect(con1.outPort, fulMecCoo.inPort[1]); connect(fulMecCoo.outPort[1], con2.inPort); connect(con2.outPort, freCoo.inPort[1]); connect(freCoo.active, swi.u[1]); connect(fulMecCoo.active, swi.u[2]); connect(swi.y, y); end CoolingModeNonIntegrated;

Buildings.Applications.DataCenters.ChillerCooled.Controls.CoolingTowerSpeed Buildings.Applications.DataCenters.ChillerCooled.Controls.CoolingTowerSpeed

Controller for the fan speed in cooling towers

Buildings.Applications.DataCenters.ChillerCooled.Controls.CoolingTowerSpeed

Information

This model describes a simple cooling tower speed controller for a chilled water system with integrated waterside economizers.

The control logics are described in the following:

Extends from Modelica.Blocks.Icons.Block (Basic graphical layout of input/output block).

Parameters

TypeNameDefaultDescription
Controller
SimpleControllercontrollerTypeModelica.Blocks.Types.Simple...Type of controller
Realk1Gain of controller [1]
TimeTi0.5Time constant of integrator block [s]
TimeTd0.1Time constant of derivative block [s]
RealyMax1Upper limit of output
RealyMin0Lower limit of output
BooleanreverseActiontrueSet to true for throttling the water flow rate through a cooling coil controller

Connectors

TypeNameDescription
input RealInputTCHWSupSetChilled water supply temperature setpoint [K]
input RealInputTCWSupSetCondenser water supply temperature setpoint [K]
input RealInputTCHWSupChilled water supply temperature [K]
input RealInputTCWSupCondenser water supply temperature [K]
output RealOutputySpeed signal for cooling tower fans
input IntegerInputcooModCooling mode signal, integer value of Buildings.Applications.DataCenters.Types.CoolingMode

Modelica definition

model CoolingTowerSpeed "Controller for the fan speed in cooling towers" extends Modelica.Blocks.Icons.Block; parameter Modelica.Blocks.Types.SimpleController controllerType=Modelica.Blocks.Types.SimpleController.PID "Type of controller"; parameter Real k( min=0, unit="1") = 1 "Gain of controller"; parameter Modelica.SIunits.Time Ti(min=Modelica.Constants.small) = 0.5 "Time constant of integrator block"; parameter Modelica.SIunits.Time Td(min=0) = 0.1 "Time constant of derivative block"; parameter Real yMax(start=1) = 1 "Upper limit of output"; parameter Real yMin=0 "Lower limit of output"; parameter Boolean reverseAction=true "Set to true for throttling the water flow rate through a cooling coil controller"; Modelica.Blocks.Interfaces.RealInput TCHWSupSet( final quantity="ThermodynamicTemperature", final unit="K", displayUnit="degC") "Chilled water supply temperature setpoint"; Modelica.Blocks.Interfaces.RealInput TCWSupSet( final quantity="ThermodynamicTemperature", final unit="K", displayUnit="degC") "Condenser water supply temperature setpoint"; Modelica.Blocks.Interfaces.RealInput TCHWSup( final quantity="ThermodynamicTemperature", final unit="K", displayUnit="degC") "Chilled water supply temperature "; Modelica.Blocks.Interfaces.RealInput TCWSup( final quantity="ThermodynamicTemperature", final unit="K", displayUnit="degC") "Condenser water supply temperature "; Modelica.Blocks.Interfaces.RealOutput y "Speed signal for cooling tower fans"; Modelica.Blocks.Sources.Constant uni(k=1) "Unit"; Modelica.Blocks.Sources.BooleanExpression pmcMod(y=cooMod == Integer( Buildings.Applications.DataCenters.Types.CoolingModes.PartialMechanical)) "Partially mechanical cooling mode"; Modelica.Blocks.Interfaces.IntegerInput cooMod "Cooling mode signal, integer value of Buildings.Applications.DataCenters.Types.CoolingMode"; Buildings.Controls.Continuous.LimPID conPID( controllerType=controllerType, k=k, Ti=Ti, Td=Td, yMax=yMax, yMin=yMin, reverseAction=reverseAction) "PID controller"; Modelica.Blocks.Math.IntegerToBoolean fmcMod(threshold=3) "Fully mechanical cooling mode"; protected Modelica.Blocks.Logical.Switch swi1 "Switch 1"; Modelica.Blocks.Logical.Switch swi2 "Switch 2"; Modelica.Blocks.Logical.Switch swi3 "Switch 3"; equation connect(TCWSupSet, swi1.u1); connect(TCHWSupSet, swi1.u3); connect(swi1.y, conPID.u_s); connect(fmcMod.y, swi2.u2); connect(TCWSup, swi2.u1); connect(TCHWSup, swi2.u3); connect(swi2.y, conPID.u_m); connect(pmcMod.y, swi3.u2); connect(uni.y, swi3.u1); connect(conPID.y, swi3.u3); connect(swi3.y, y); connect(fmcMod.y, swi1.u2); connect(cooMod, fmcMod.u); end CoolingTowerSpeed;

Buildings.Applications.DataCenters.ChillerCooled.Controls.Reheat Buildings.Applications.DataCenters.ChillerCooled.Controls.Reheat

Model that implements an on and off controller for a reheater

Buildings.Applications.DataCenters.ChillerCooled.Controls.Reheat

Information

This model can be used to generate on/off signal for the reheater inside the AHU.

This reheater will be on only if the following two conditions are satisfied at the same time:

In addition, a deadband and waiting time is used to avoid frequent switching.

Parameters

TypeNameDefaultDescription
RealyValSwi Switch point for valve signal [1]
RealyValDeaBan Deadband for valve signal [1]
TemperatureDifferencedTSwi Switch point for temperature difference [K]
TemperatureDifferencedTDeaBan Deadband for temperature difference [K]
TimetWai Waiting time [s]

Connectors

TypeNameDescription
input RealInputyValValve position [1]
input RealInputdTTemperature difference [K]
output BooleanOutputyOn and off signal for the reheater

Modelica definition

model Reheat "Model that implements an on and off controller for a reheater" parameter Real yValSwi( min=0, max=1, unit="1") "Switch point for valve signal"; parameter Real yValDeaBan( min=0, max=1, unit="1") "Deadband for valve signal"; parameter Modelica.SIunits.TemperatureDifference dTSwi "Switch point for temperature difference"; parameter Modelica.SIunits.TemperatureDifference dTDeaBan "Deadband for temperature difference"; parameter Modelica.SIunits.Time tWai "Waiting time"; Modelica.Blocks.Interfaces.RealInput yVal( min=0, max=1, unit="1") "Valve position"; Modelica.Blocks.Interfaces.RealInput dT(final quantity="ThermodynamicTemperature", final unit="K") "Temperature difference"; Modelica.Blocks.Interfaces.BooleanOutput y "On and off signal for the reheater"; Modelica.StateGraph.InitialStepWithSignal off "Off"; Modelica.StateGraph.StepWithSignal on "On"; Modelica.StateGraph.Transition offToOn( enableTimer=true, waitTime=tWai, condition=yVal <= yValSwi - yValDeaBan and dT < dTSwi - dTDeaBan) "Conditions that switch off to on"; Modelica.StateGraph.Transition onToOff( condition=yVal > yValSwi + yValDeaBan or dT > dTSwi + dTDeaBan, enableTimer=true, waitTime=tWai) "Conditions that switch on to off"; inner Modelica.StateGraph.StateGraphRoot stateGraphRoot; equation connect(off.outPort[1], offToOn.inPort); connect(offToOn.outPort, on.inPort[1]); connect(on.outPort[1], onToOff.inPort); connect(onToOff.outPort, off.inPort[1]); connect(on.active, y); end Reheat;

Buildings.Applications.DataCenters.ChillerCooled.Controls.VariableSpeedPumpStage Buildings.Applications.DataCenters.ChillerCooled.Controls.VariableSpeedPumpStage

Staging control for variable speed pumps

Buildings.Applications.DataCenters.ChillerCooled.Controls.VariableSpeedPumpStage

Information

This model implements a simple staging control logic for variable speed pumps.

Extends from Modelica.Blocks.Icons.Block (Basic graphical layout of input/output block).

Parameters

TypeNameDefaultDescription
TimetWai Waiting time [s]
MassFlowRatem_flow_nominal Nominal mass flow rate of the identical variable-speed pumps [kg/s]
RealminSpe0.05Minimum speed ratio required by variable speed pumps [1]
MassFlowRatecriPoiFlo0.7*m_flow_nominalCritcal point of flowrate for switch pump on or off [kg/s]
MassFlowRatedeaBanFlo0.1*m_flow_nominalDeadband for critical point of flowrate [kg/s]
RealcriPoiSpe0.5Critical point of speed signal for switching on or off
RealdeaBanSpe0.3Deadband for critical point of speed signal

Connectors

TypeNameDescription
input RealInputmasFloPumTotal mass flowrate in the variable speed pumps
input RealInputspeSigSpeed signal
output RealOutputy[2]On/off signal - 0: off; 1: on

Modelica definition

model VariableSpeedPumpStage "Staging control for variable speed pumps" extends Modelica.Blocks.Icons.Block; parameter Modelica.SIunits.Time tWai "Waiting time"; parameter Modelica.SIunits.MassFlowRate m_flow_nominal "Nominal mass flow rate of the identical variable-speed pumps"; parameter Real minSpe( unit="1", min=0, max=1) = 0.05 "Minimum speed ratio required by variable speed pumps"; parameter Modelica.SIunits.MassFlowRate criPoiFlo=0.7*m_flow_nominal "Critcal point of flowrate for switch pump on or off"; parameter Modelica.SIunits.MassFlowRate deaBanFlo=0.1*m_flow_nominal "Deadband for critical point of flowrate"; parameter Real criPoiSpe=0.5 "Critical point of speed signal for switching on or off"; parameter Real deaBanSpe=0.3 "Deadband for critical point of speed signal"; Modelica.Blocks.Interfaces.RealInput masFloPum "Total mass flowrate in the variable speed pumps"; Modelica.Blocks.Interfaces.RealInput speSig "Speed signal"; Modelica.Blocks.Interfaces.RealOutput y[2] "On/off signal - 0: off; 1: on"; Modelica.StateGraph.Transition con1( enableTimer=true, waitTime=tWai, condition=speSig > minSpe) "Fire condition 1: free cooling to partially mechanical cooling"; Modelica.StateGraph.StepWithSignal oneOn(nIn=2, nOut=2) "One chiller is commanded on"; Modelica.StateGraph.InitialStep off(nIn=1) "Free cooling mode"; Modelica.StateGraph.StepWithSignal twoOn "Two chillers are commanded on"; Modelica.StateGraph.Transition con2( enableTimer=true, waitTime=tWai, condition=speSig > criPoiSpe + deaBanSpe and masFloPum > criPoiFlo + deaBanFlo) "Fire condition 2: partially mechanical cooling to fully mechanical cooling"; Modelica.StateGraph.Transition con3( enableTimer=true, waitTime=tWai, condition=speSig < criPoiSpe - deaBanSpe or masFloPum < criPoiFlo - deaBanFlo) "Fire condition 3: fully mechanical cooling to partially mechanical cooling"; Modelica.StateGraph.Transition con4( enableTimer=true, waitTime=tWai, condition=speSig <= minSpe) "Fire condition 4: partially mechanical cooling to free cooling"; inner Modelica.StateGraph.StateGraphRoot stateGraphRoot; Modelica.Blocks.Tables.CombiTable1Ds combiTable1Ds(table=[0, 0, 0; 1, 1, 0; 2, 1, 1]) "Determine which pump should be on - rotation control is not considered here"; Buildings.Controls.OBC.CDL.Conversions.BooleanToInteger booToInt(final integerTrue=1, final integerFalse=0); Buildings.Controls.OBC.CDL.Conversions.BooleanToInteger booToInt1(final integerFalse=0, final integerTrue=2); Buildings.Controls.OBC.CDL.Integers.Add addInt; Buildings.Controls.OBC.CDL.Conversions.IntegerToReal intToRea; equation connect(off.outPort[1], con1.inPort); connect(con1.outPort, oneOn.inPort[1]); connect(con2.inPort, oneOn.outPort[1]); connect(con2.outPort, twoOn.inPort[1]); connect(twoOn.outPort[1], con3.inPort); connect(con4.outPort, off.inPort[1]); connect(con3.outPort, oneOn.inPort[2]); connect(con4.inPort, oneOn.outPort[2]); connect(combiTable1Ds.y, y); connect(booToInt.u, oneOn.active); connect(twoOn.active, booToInt1.u); connect(booToInt.y, addInt.u1); connect(booToInt1.y, addInt.u2); connect(addInt.y, intToRea.u); connect(intToRea.y, combiTable1Ds.u); end VariableSpeedPumpStage;