Buildings.Examples.VAVReheat.BaseClasses.Controls
Package with controller models
Information
Extends from Modelica.Icons.VariantsPackage (Icon for package containing variants).
Package Content
| Name | Description |
|---|---|
 ControlBus
|
Empty control bus that is adapted to the signals connected to it |
 DuctStaticPressureSetpoint
|
Computes the duct static pressure setpoint |
 Economizer
|
Controller for economizer |
 FanVFD
|
Controller for fan revolution |
 FreezeStat
|
Freeze thermostat with timed lockout |
 ModeSelector
|
Finite State Machine for the operational modes |
 OperationModes
|
Enumeration for modes of operation |
 PreCoolingStarter
|
Outputs true when precooling should start |
 RoomTemperatureSetpoint
|
Set point scheduler for room temperature |
 RoomVAV
|
Controller for room VAV box |
 State
|
Block that outputs the mode if the state is active, or zero otherwise |
 SupplyAirTemperature
|
Control block for tracking the supply air temperature set point |
 SupplyAirTemperatureSetpoint
|
Block computing the supply air temperature set point based on the operation mode |
 SystemHysteresis
|
Block that applies hysteresis and a minimum on timer to a control signal |
 Examples
|
Example models to test the components |
Types and constants
type OperationModes = enumeration( occupied "Occupied", unoccupiedOff "Unoccupied off", unoccupiedNightSetBack "Unoccupied, night set back", unoccupiedWarmUp "Unoccupied, warm-up", unoccupiedPreCool "Unoccupied, pre-cool", safety "Safety (smoke, fire, etc.)") "Enumeration for modes of operation";
Buildings.Examples.VAVReheat.BaseClasses.Controls.ControlBus
Empty control bus that is adapted to the signals connected to it
Information
This connector defines the expandable connector ControlBus that
is used to connect control signals.
Note, this connector is empty. When using it, the actual content is
constructed by the signals connected to this bus.
Extends from Modelica.Icons.SignalBus (Icon for signal bus).
Modelica definition
expandable connector ControlBus
"Empty control bus that is adapted to the signals connected to it"
extends Modelica.Icons.SignalBus;
end ControlBus;
Buildings.Examples.VAVReheat.BaseClasses.Controls.DuctStaticPressureSetpoint
Computes the duct static pressure setpoint
Information
Extends from Modelica.Blocks.Interfaces.MISO (Multiple Input Single Output continuous control block).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Integer | nin | 1 | Number of inputs |
| AbsolutePressure | pMin | 100 | Minimum duct static pressure setpoint [Pa] |
| AbsolutePressure | pMax | 410 | Maximum duct static pressure setpoint [Pa] |
| Real | k | 0.1 | Gain of controller |
| Time | Ti | 60 | Time constant of integrator block [s] |
| Time | Td | 60 | Time constant of derivative block [s] |
| SimpleController | controllerType | Modelica.Blocks.Types.Simple... | Type of controller |
Connectors
| Type | Name | Description |
|---|---|---|
| input RealInput | u[nin] | Connector of Real input signals |
| output RealOutput | y | Connector of Real output signal |
Modelica definition
model DuctStaticPressureSetpoint "Computes the duct static pressure setpoint"
extends Modelica.Blocks.Interfaces.MISO;
parameter Modelica.Units.SI.AbsolutePressure pMin(displayUnit="Pa") = 100
"Minimum duct static pressure setpoint";
parameter Modelica.Units.SI.AbsolutePressure pMax(displayUnit="Pa") = 410
"Maximum duct static pressure setpoint";
parameter Real k=0.1 "Gain of controller";
parameter Modelica.Units.SI.Time Ti=60 "Time constant of integrator block";
parameter Modelica.Units.SI.Time Td=60 "Time constant of derivative block";
parameter Modelica.Blocks.Types.SimpleController controllerType=Modelica.Blocks.Types.SimpleController.PI
"Type of controller";
Buildings.Controls.Continuous.LimPID limPID(
controllerType=controllerType,
k=k,
Ti=Ti,
Td=Td,
initType=Modelica.Blocks.Types.Init.InitialState,
reverseActing=false);
protected
Buildings.Utilities.Math.Max max(final nin=nin);
Modelica.Blocks.Sources.Constant ySet(k=0.9)
"Setpoint for maximum damper position";
Modelica.Blocks.Math.Add dp(final k2=-1) "Pressure difference";
Modelica.Blocks.Sources.Constant pMaxSig(k=pMax);
Modelica.Blocks.Sources.Constant pMinSig(k=pMin);
Modelica.Blocks.Math.Add pSet "Pressure setpoint";
Modelica.Blocks.Math.Product product;
equation
connect(max.u, u);
connect(ySet.y, limPID.u_s);
connect(max.y, limPID.u_m);
connect(limPID.y, product.u1);
connect(pMaxSig.y, dp.u1);
connect(pMinSig.y, dp.u2);
connect(dp.y, product.u2);
connect(pMinSig.y, pSet.u2);
connect(pSet.y, y);
connect(product.y, pSet.u1);
end DuctStaticPressureSetpoint;
Buildings.Examples.VAVReheat.BaseClasses.Controls.Economizer
Controller for economizer
Information
This is a controller for an economizer, that adjusts the mixed air dampers to fulfill three control functions.
- Freeze protection, based on the mixed air temperature measurement
- Minimum outside air requirement, based on the outdoor air flow rate measurement
- Supply air cooling, based on the logic implemented in Buildings.Examples.VAVReheat.BaseClasses.Controls.SupplyAirTemperature, with the additional condition that when the outside air dry bulb is greater than the return air dry bulb, economizer cooling is disabled.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Boolean | have_reset | false | Set to true to reset the outdoor air damper controllers with the enable signal |
| Boolean | have_frePro | false | Set to true to enable freeze protection (mixed air low temperature control) |
| Temperature | TFreSet | 277.15 | Lower limit of mixed air temperature for freeze protection [K] |
| TemperatureDifference | dTLock | 1 | Temperature difference between return and outdoor air for economizer lockout [K] |
| VolumeFlowRate | VOut_flow_min | Minimum outside air volume flow rate [m3/s] | |
| SimpleController | controllerType | Modelica.Blocks.Types.Simple... | Type of controller |
| Real | k | 0.05 | Gain of controller |
| Time | Ti | 120 | Time constant of integrator block [s] |
Connectors
| Type | Name | Description |
|---|---|---|
| input BooleanInput | uEna | Enable signal for economizer |
| ControlBus | controlBus | Control bus |
| input RealInput | uOATSup | Control signal for outdoor air damper from supply temperature controller |
| input RealInput | TMix | Measured mixed air temperature |
| input RealInput | VOut_flow | Measured outside air flow rate |
| input RealInput | TRet | Return air temperature |
| output RealOutput | yRet | Control signal for return air damper |
| output RealOutput | yOA | Control signal for outside air damper |
Modelica definition
block Economizer "Controller for economizer"
import Buildings.Examples.VAVReheat.BaseClasses.Controls.OperationModes;
parameter Boolean have_reset = false
"Set to true to reset the outdoor air damper controllers with the enable signal";
parameter Boolean have_frePro = false
"Set to true to enable freeze protection (mixed air low temperature control)";
parameter Modelica.Units.SI.Temperature TFreSet=277.15
"Lower limit of mixed air temperature for freeze protection";
parameter Modelica.Units.SI.TemperatureDifference dTLock(final min=0.1) = 1
"Temperature difference between return and outdoor air for economizer lockout";
parameter Modelica.Units.SI.VolumeFlowRate VOut_flow_min(min=0)
"Minimum outside air volume flow rate";
parameter Modelica.Blocks.Types.SimpleController controllerType=Modelica.Blocks.Types.SimpleController.PI
"Type of controller";
parameter Real k = 0.05 "Gain of controller";
parameter Modelica.Units.SI.Time Ti=120 "Time constant of integrator block";
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput uEna
"Enable signal for economizer";
ControlBus controlBus "Control bus";
Modelica.Blocks.Interfaces.RealInput uOATSup
"Control signal for outdoor air damper from supply temperature controller";
Modelica.Blocks.Interfaces.RealInput TMix if have_frePro
"Measured mixed air temperature";
Modelica.Blocks.Interfaces.RealInput VOut_flow
"Measured outside air flow rate";
Modelica.Blocks.Interfaces.RealInput TRet "Return air temperature";
Modelica.Blocks.Interfaces.RealOutput yRet
"Control signal for return air damper";
Modelica.Blocks.Interfaces.RealOutput yOA
"Control signal for outside air damper";
Modelica.Blocks.Math.Gain gain(k=1/VOut_flow_min) "Normalize mass flow rate";
Buildings.Controls.OBC.CDL.Reals.PID conV_flow(
controllerType=controllerType,
k=k,
Ti=Ti,
yMax=1,
yMin=0,
Td=60)
"Controller for outside air flow rate";
Modelica.Blocks.Sources.Constant uni(k=1) "Unity signal";
Modelica.Blocks.Sources.Constant closed(k=0) "Signal to close OA damper";
Buildings.Controls.OBC.CDL.Reals.PID yOATFre(
controllerType=controllerType,
k=k,
Ti=Ti,
Td=60,
yMax=1,
yMin=0,
reverseActing=false) if have_frePro
"Controller of outdoor damper to track freeze temperature setpoint";
Buildings.Controls.OBC.CDL.Reals.Min minFrePro
"Takes lower signal (limits damper opening for freeze protection)";
Modelica.Blocks.Sources.Constant TFre(k=TFreSet)
"Setpoint for freeze protection";
Buildings.Controls.OBC.CDL.Reals.Subtract invSig
"Invert control signal for interlocked damper";
Modelica.Blocks.Logical.Hysteresis hysLoc(final uLow=0, final uHigh=dTLock)
"Hysteresis for economizer lockout";
Modelica.Blocks.Math.Feedback feedback;
Buildings.Controls.OBC.CDL.Reals.Switch swiOA
"Switch to close outdoor air damper";
Modelica.Blocks.Sources.Constant one(k=1) if not have_frePro
"Fill value in case freeze protection is disabled";
Buildings.Controls.OBC.CDL.Reals.Switch swiModClo
"Switch between modulating or closing outdoor air damper";
Buildings.Controls.OBC.CDL.Reals.Max maxOutDam
"Select larger of the outdoor damper signals";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant conOne(
final k=1)
"Constant 1";
equation
connect(VOut_flow, gain.u);
connect(gain.y, conV_flow.u_m);
connect(uni.y, conV_flow.u_s);
connect(yOATFre.y, minFrePro.u1);
connect(yRet, invSig.y);
connect(feedback.y, hysLoc.u);
connect(TRet, feedback.u1);
connect(controlBus.TOut, feedback.u2);
connect(closed.y, swiOA.u3);
connect(hysLoc.y, swiOA.u2);
connect(uOATSup, swiOA.u1);
connect(one.y, minFrePro.u1);
connect(yOATFre.u_s, TFre.y);
connect(TMix, yOATFre.u_m);
connect(swiModClo.y, yOA);
connect(uEna, swiModClo.u2);
connect(closed.y, swiModClo.u3);
connect(maxOutDam.u1, swiOA.y);
connect(conV_flow.y, maxOutDam.u2);
connect(minFrePro.y, swiModClo.u1);
connect(maxOutDam.y, minFrePro.u2);
connect(swiModClo.y, invSig.u2);
connect(conOne.y, invSig.u1);
end Economizer;
Buildings.Examples.VAVReheat.BaseClasses.Controls.FanVFD
Controller for fan revolution
Information
PI controller for the fan speed. The controller outputs y = 0 if the fan control signal is off, e.g., if uFan = false.
Extends from Modelica.Blocks.Interfaces.SISO (Single Input Single Output continuous control block).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Real | xSet_nominal | Nominal setpoint (used for normalization) | |
| Real | r_N_min | 0.01 | Minimum normalized fan speed |
| Init | initType | Modelica.Blocks.Types.Init.N... | Type of initialization (1: no init, 2: steady state, 3/4: initial output) |
| Real | y_start | 0 | Initial or guess value of output (= state) |
| Setpoint tracking | |||
| SimpleController | controllerType | Modelica.Blocks.Types.Simple... | Type of controller |
| Real | k | 0.5 | Gain of controller |
| Time | Ti | 15 | Time constant of integrator block [s] |
Connectors
| Type | Name | Description |
|---|---|---|
| input RealInput | u | Connector of Real input signal |
| output RealOutput | y | Connector of Real output signal |
| input RealInput | u_m | Connector of measurement input signal |
| input BooleanInput | uFan | Set to true to enable the fan on |
Modelica definition
block FanVFD "Controller for fan revolution"
extends Modelica.Blocks.Interfaces.SISO;
import Buildings.Examples.VAVReheat.BaseClasses.Controls.OperationModes;
Buildings.Controls.OBC.CDL.Reals.PIDWithReset con(
r=xSet_nominal,
yMax=1,
Td=60,
yMin=r_N_min,
k=k,
Ti=Ti,
controllerType=controllerType)
"Controller";
parameter Real xSet_nominal "Nominal setpoint (used for normalization)";
Modelica.Blocks.Sources.Constant off(k=0) "Off signal";
Modelica.Blocks.Interfaces.RealInput u_m
"Connector of measurement input signal";
parameter Real r_N_min=0.01 "Minimum normalized fan speed";
parameter Modelica.Blocks.Types.Init initType=Modelica.Blocks.Types.Init.NoInit
"Type of initialization (1: no init, 2: steady state, 3/4: initial output)";
parameter Real y_start=0 "Initial or guess value of output (= state)";
parameter Modelica.Blocks.Types.SimpleController
controllerType=Modelica.Blocks.Types.SimpleController.PI
"Type of controller";
parameter Real k=0.5 "Gain of controller";
parameter Modelica.Units.SI.Time Ti=15 "Time constant of integrator block";
Buildings.Controls.OBC.CDL.Reals.Switch swi;
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput uFan
"Set to true to enable the fan on";
equation
connect(con.y, swi.u1);
connect(off.y, swi.u3);
connect(swi.u2, uFan);
connect(swi.y, y);
connect(con.trigger, uFan);
connect(con.u_s, u);
connect(u_m, con.u_m);
end FanVFD;
Buildings.Examples.VAVReheat.BaseClasses.Controls.FreezeStat
Freeze thermostat with timed lockout
Information
Freeze stat that outputs true if freeze protection should be engaged.
The freeze stat regulates around a set point. When it triggers freeze protection,
then the freeze protection stays engaged for at least delayTime.
It only becomes disengaged after this time period if the measured temperature is above
the set point.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Real | lockoutTime | 900 | Delay time [s] |
| Real | TSet | 276.15 | Temperature below which the freeze protection starts [K] |
Connectors
| Type | Name | Description |
|---|---|---|
| input RealInput | u | Connector of Real input signal used as measurement signal [K] |
| output BooleanOutput | y | Connector of Real output signal used as actuator signal |
Modelica definition
model FreezeStat "Freeze thermostat with timed lockout"
parameter Real lockoutTime(
final quantity="Time",
final unit="s",
displayUnit="min",
min=60) = 900
"Delay time";
parameter Real TSet(
final quantity="ThermodynamicTemperature",
final unit="K",
displayUnit="degC") = 276.15 "Temperature below which the freeze protection starts";
Buildings.Controls.OBC.CDL.Interfaces.RealInput u(
final quantity="ThermodynamicTemperature",
final unit="K",
displayUnit="degC")
"Connector of Real input signal used as measurement signal";
Buildings.Controls.OBC.CDL.Interfaces.BooleanOutput y
"Connector of Real output signal used as actuator signal";
Buildings.Controls.OBC.CDL.Logical.TrueDelay locOut(final delayTime=
lockoutTime) "If freeze stat triggers, keep it on for specified time";
Buildings.Controls.OBC.CDL.Logical.Not freStaSig "Signal for freeze stat";
Buildings.Controls.OBC.CDL.Reals.GreaterThreshold greThr(
final t=TSet,
final h=0.5)
"Greater comparison";
equation
connect(locOut.y, freStaSig.u);
connect(freStaSig.y, y);
connect(greThr.y, locOut.u);
connect(greThr.u, u);
end FreezeStat;
Buildings.Examples.VAVReheat.BaseClasses.Controls.ModeSelector
Finite State Machine for the operational modes
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| TemperatureDifference | delTRooOnOff | 1 | Deadband in room temperature between occupied on and occupied off [K] |
| Temperature | TRooSetHeaOcc | 293.15 | Set point for room air temperature during heating mode [K] |
| Temperature | TRooSetCooOcc | 299.15 | Set point for room air temperature during cooling mode [K] |
Connectors
| Type | Name | Description |
|---|---|---|
| ControlBus | cb | |
| output BooleanOutput | yFan | True if the fans are to be switched on |
| output BooleanOutput | yEco | True if the economizer is enabled |
Modelica definition
model ModeSelector "Finite State Machine for the operational modes"
Modelica.StateGraph.InitialStepWithSignal initialStepWithSignal(nIn=0, nOut=1);
Modelica.StateGraph.Transition start "Starts the system";
State unOccOff(
mode=Buildings.Examples.VAVReheat.BaseClasses.Controls.OperationModes.unoccupiedOff,
nIn=3,
nOut=4) "Unoccupied off mode, no coil protection";
State unOccNigSetBac(
nOut=2,
mode=Buildings.Examples.VAVReheat.BaseClasses.Controls.OperationModes.unoccupiedNightSetBack,
nIn=1) "Unoccupied night set back";
Modelica.StateGraph.Transition t2(
enableTimer=true,
waitTime=60,
condition=TRooMinErrHea.y > delTRooOnOff/2);
parameter Modelica.Units.SI.TemperatureDifference delTRooOnOff(min=0.1) = 1
"Deadband in room temperature between occupied on and occupied off";
parameter Modelica.Units.SI.Temperature TRooSetHeaOcc=293.15
"Set point for room air temperature during heating mode";
parameter Modelica.Units.SI.Temperature TRooSetCooOcc=299.15
"Set point for room air temperature during cooling mode";
Modelica.StateGraph.Transition t1(condition=delTRooOnOff/2 < -TRooMinErrHea.y,
enableTimer=true,
waitTime=30*60);
inner Modelica.StateGraph.StateGraphRoot stateGraphRoot;
ControlBus cb;
Modelica.Blocks.Routing.RealPassThrough TRooSetHea
"Current heating setpoint temperature";
State morWarUp(mode=Buildings.Examples.VAVReheat.BaseClasses.Controls.OperationModes.unoccupiedWarmUp,
nIn=2,
nOut=1) "Morning warm up";
Modelica.StateGraph.TransitionWithSignal t6(enableTimer=true, waitTime=60);
Modelica.Blocks.Logical.LessEqualThreshold occThrSho(threshold=1800)
"Signal to allow transition into morning warmup";
Modelica.StateGraph.TransitionWithSignal t5;
State occ(
mode=Buildings.Examples.VAVReheat.BaseClasses.Controls.OperationModes.occupied,
nIn=3,
nOut=1)
"Occupied mode";
Modelica.Blocks.Routing.RealPassThrough TRooMin;
Modelica.Blocks.Math.Feedback TRooMinErrHea "Room control error for heating";
Modelica.StateGraph.Transition t3(condition=TRooMin.y + delTRooOnOff/2 >
TRooSetHeaOcc or occupied.y);
Modelica.Blocks.Routing.BooleanPassThrough occupied
"outputs true if building is occupied";
Modelica.StateGraph.TransitionWithSignal t4(enableTimer=false);
State morPreCoo(
nIn=1,
mode=Buildings.Examples.VAVReheat.BaseClasses.Controls.OperationModes.unoccupiedPreCool,
nOut=1) "Pre-cooling mode";
Modelica.StateGraph.Transition t7(condition=TRooMin.y - delTRooOnOff/2 <
TRooSetCooOcc or occupied.y);
Modelica.Blocks.Routing.RealPassThrough TRooAve "Average room temperature";
Modelica.Blocks.Sources.BooleanExpression booleanExpression(
y=occThrSho.y and (TRooAve.y < TRooSetHeaOcc))
"Test that outputs true if room temperature is below occupied heating and system should be switched on soon";
PreCoolingStarter preCooSta(TRooSetCooOcc=TRooSetCooOcc)
"Model to start pre-cooling";
Modelica.StateGraph.TransitionWithSignal t9;
Modelica.Blocks.Logical.Not not1;
Modelica.Blocks.Logical.And and2;
Modelica.Blocks.Logical.Not not2;
Modelica.StateGraph.TransitionWithSignal t8
"changes to occupied in case precooling is deactivated";
Modelica.Blocks.MathInteger.Sum sum(nu=6);
Modelica.Blocks.Interfaces.BooleanOutput yFan
"True if the fans are to be switched on";
Modelica.Blocks.MathBoolean.Or or1(nu=4);
Modelica.Blocks.Interfaces.BooleanOutput yEco
"True if the economizer is enabled";
Modelica.Blocks.MathBoolean.Or or2(nu=2) "Occupied or pre-cool mode";
Buildings.Controls.OBC.CDL.Logical.And and3
"(Occupied or pre-cool mode) and fan on";
Modelica.Blocks.Math.BooleanToInteger modIni(integerTrue=Integer(Buildings.Examples.VAVReheat.BaseClasses.Controls.OperationModes.unoccupiedOff))
"Initial operation mode";
equation
connect(start.outPort, unOccOff.inPort[1]);
connect(initialStepWithSignal.outPort[1], start.inPort);
connect(unOccOff.outPort[1], t2.inPort);
connect(t2.outPort, unOccNigSetBac.inPort[1]);
connect(unOccNigSetBac.outPort[1], t1.inPort);
connect(t1.outPort, unOccOff.inPort[2]);
connect(cb.dTNexOcc, occThrSho.u);
connect(t6.outPort, morWarUp.inPort[1]);
connect(t5.outPort, morWarUp.inPort[2]);
connect(unOccNigSetBac.outPort[2], t5.inPort);
connect(cb.TRooMin, TRooMin.u);
connect(TRooSetHea.y, TRooMinErrHea.u1);
connect(TRooMin.y, TRooMinErrHea.u2);
connect(unOccOff.outPort[2], t6.inPort);
connect(morWarUp.outPort[1], t3.inPort);
connect(cb.occupied, occupied.u);
connect(occ.outPort[1], t4.inPort);
connect(t4.outPort, unOccOff.inPort[3]);
connect(cb.TRooAve, TRooAve.u);
connect(preCooSta.y, t9.condition);
connect(t9.outPort, morPreCoo.inPort[1]);
connect(unOccOff.outPort[3], t9.inPort);
connect(cb, preCooSta.controlBus);
connect(morPreCoo.outPort[1], t7.inPort);
connect(t7.outPort, occ.inPort[2]);
connect(t3.outPort, occ.inPort[1]);
connect(occThrSho.y, not1.u);
connect(not1.y, and2.u2);
connect(and2.y, t4.condition);
connect(occupied.y, not2.u);
connect(not2.y, and2.u1);
connect(cb.TRooSetHea, TRooSetHea.u);
connect(t8.outPort, occ.inPort[3]);
connect(unOccOff.outPort[4], t8.inPort);
connect(occupied.y, t8.condition);
connect(morPreCoo.y, sum.u[1]);
connect(morWarUp.y, sum.u[2]);
connect(occ.y, sum.u[3]);
connect(unOccOff.y, sum.u[4]);
connect(unOccNigSetBac.y, sum.u[5]);
connect(yFan, or1.y);
connect(unOccNigSetBac.active, or1.u[1]);
connect(occ.active, or1.u[2]);
connect(morWarUp.active, or1.u[3]);
connect(morPreCoo.active, or1.u[4]);
connect(yEco, and3.y);
connect(or1.y, and3.u1);
connect(or2.y, and3.u2);
connect(occ.active, or2.u[1]);
connect(morPreCoo.active, or2.u[2]);
connect(initialStepWithSignal.active, modIni.u);
connect(sum.y, cb.controlMode);
connect(modIni.y, sum.u[6]);
connect(t6.condition, booleanExpression.y);
connect(t5.condition, booleanExpression.y);
end ModeSelector;
Buildings.Examples.VAVReheat.BaseClasses.Controls.OperationModes
Enumeration for modes of operation
Modelica definition
type OperationModes = enumeration(
occupied "Occupied",
unoccupiedOff "Unoccupied off",
unoccupiedNightSetBack "Unoccupied, night set back",
unoccupiedWarmUp "Unoccupied, warm-up",
unoccupiedPreCool "Unoccupied, pre-cool",
safety "Safety (smoke, fire, etc.)") "Enumeration for modes of operation";
Buildings.Examples.VAVReheat.BaseClasses.Controls.PreCoolingStarter
Outputs true when precooling should start
Information
Extends from Modelica.Blocks.Interfaces.BooleanSignalSource (Base class for Boolean signal sources).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Temperature | TOutLim | 286.15 | Limit for activating precooling [K] |
| Temperature | TRooSetCooOcc | Set point for room air temperature during cooling mode [K] |
Connectors
| Type | Name | Description |
|---|---|---|
| output BooleanOutput | y | Connector of Boolean output signal |
| ControlBus | controlBus |
Modelica definition
block PreCoolingStarter "Outputs true when precooling should start"
extends Modelica.Blocks.Interfaces.BooleanSignalSource;
parameter Modelica.Units.SI.Temperature TOutLim=286.15
"Limit for activating precooling";
parameter Modelica.Units.SI.Temperature TRooSetCooOcc
"Set point for room air temperature during cooling mode";
BaseClasses.Controls.ControlBus controlBus;
Modelica.Blocks.Logical.GreaterThreshold greater(threshold=TRooSetCooOcc);
Modelica.Blocks.Logical.LessThreshold greater2(threshold=1800);
Modelica.Blocks.Logical.LessThreshold greater1(threshold=TOutLim);
Modelica.Blocks.MathBoolean.And and3(nu=3);
equation
connect(controlBus.dTNexOcc, greater2.u);
connect(controlBus.TRooAve, greater.u);
connect(controlBus.TOut, greater1.u);
connect(and3.y, y);
connect(greater.y, and3.u[1]);
connect(greater1.y, and3.u[2]);
connect(greater2.y, and3.u[3]);
end PreCoolingStarter;
Buildings.Examples.VAVReheat.BaseClasses.Controls.RoomTemperatureSetpoint
Set point scheduler for room temperature
Information
Extends from Modelica.Blocks.Icons.Block (Basic graphical layout of input/output block).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Temperature | THeaOn | 293.15 | Heating setpoint during on [K] |
| Temperature | THeaOff | 285.15 | Heating setpoint during off [K] |
| Temperature | TCooOn | 297.15 | Cooling setpoint during on [K] |
| Temperature | TCooOff | 303.15 | Cooling setpoint during off [K] |
Connectors
| Type | Name | Description |
|---|---|---|
| ControlBus | controlBus |
Modelica definition
block RoomTemperatureSetpoint "Set point scheduler for room temperature"
extends Modelica.Blocks.Icons.Block;
import Buildings.Examples.VAVReheat.BaseClasses.Controls.OperationModes;
parameter Modelica.Units.SI.Temperature THeaOn=293.15
"Heating setpoint during on";
parameter Modelica.Units.SI.Temperature THeaOff=285.15
"Heating setpoint during off";
parameter Modelica.Units.SI.Temperature TCooOn=297.15
"Cooling setpoint during on";
parameter Modelica.Units.SI.Temperature TCooOff=303.15
"Cooling setpoint during off";
BaseClasses.Controls.ControlBus controlBus;
Modelica.Blocks.Routing.IntegerPassThrough mode;
Modelica.Blocks.Sources.RealExpression setPoiHea(
y(final unit="K", displayUnit="degC")=if (mode.y == Integer(OperationModes.occupied) or mode.y == Integer(OperationModes.unoccupiedWarmUp)
or mode.y == Integer(OperationModes.safety)) then THeaOn else THeaOff);
Modelica.Blocks.Sources.RealExpression setPoiCoo(
y(final unit="K", displayUnit="degC")=if (mode.y == Integer(OperationModes.occupied) or
mode.y == Integer(OperationModes.unoccupiedPreCool) or
mode.y == Integer(OperationModes.safety)) then TCooOn else TCooOff)
"Cooling setpoint";
equation
connect(controlBus.controlMode,mode. u);
connect(setPoiHea.y, controlBus.TRooSetHea);
connect(setPoiCoo.y, controlBus.TRooSetCoo);
end RoomTemperatureSetpoint;
Buildings.Examples.VAVReheat.BaseClasses.Controls.RoomVAV
Controller for room VAV box
Information
Controller for terminal VAV box with hot water reheat.
It is based on the control logic "dual maximum with constant volume heating" as
described in the Advanced VAV System Design Guide (EDR 2007).
The controller could be used for units with the pressure independent damper and the
units with the exponential damper, by setting the flag have_preIndDam.
Two separate control loops, the cooling loop and the heating loop, are implemented
to maintain space temperature within a temperature dead band (with a required minimum
width of 0.5 K).
For the terminal boxes with the pressure independent damper, the damper control
signal yDam corresponds to the discharge air flow rate
set point, normalized to the nominal value. While for the boxes with the exponential
damper, the damper position yDam is controlled by a PID loop to track the discharge
airflow setpoint.
The control signal for the reheat coil valve yVal corresponds to the
fractional opening (1 corresponding to the valve fully open).
For the termnal boxes with the pressure independent damper (have_preIndDam=true),
-
Inside the dead band,
yDamis fixed at the minimum valueratVFloMinandyValis 0. -
In heating demand,
yDamis fixed at the heating valueratVFloHea, andyValis modulated between 0 and 1. -
In cooling demand,
yDamis modulated between the minimum valueratVFloMinand 1, andyValis 0.
For the termnal boxes with the exponential damper (have_preIndDam=false),
-
Inside the dead band,
yDamis controlled to track the minimum valueratVFloMinandyValis 0. -
In heating demand,
yDamis controlled to track the heating valueratVFloHea, andyValis modulated between 0 and 1. -
In cooling demand,
yDamis controlled to track the airflow rate modulated between the minimum valueratVFloMinand 1, andyValis 0.
Note that a single maximum control logic can be represented by simply setting
ratVFloHea equal to ratVFloMin (default setting).
References
EDR (Energy Design Resources). Advanced Variable Air Volume System Design Guide. Pacific Gas and Electric Company, 2007.
Extends from Modelica.Blocks.Icons.Block (Basic graphical layout of input/output block).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Boolean | have_preIndDam | true | True: the terminal box has pressure independent damper |
| Real | ratVFloMin | 0.3 | Minimum airflow set point (ratio to nominal) [1] |
| Real | ratVFloHea | ratVFloMin | Heating airflow set point (ratio to nominal) [1] |
| VolumeFlowRate | V_flow_nominal | 0.1 | Norminal air volume flow rate [m3/s] |
| Cooling controller | |||
| SimpleController | cooController | Buildings.Controls.OBC.CDL.T... | Type of controller |
| Real | kCoo | 0.1 | Gain of controller |
| Time | TiCoo | 120 | Time constant of integrator block [s] |
| Time | TdCoo | 60 | Time constant of derivative block [s] |
| Heating controller | |||
| SimpleController | heaController | Buildings.Controls.OBC.CDL.T... | Type of controller |
| Real | kHea | 0.1 | Gain of controller |
| Time | TiHea | 120 | Time constant of integrator block [s] |
| Time | TdHea | 60 | Time constant of derivative block [s] |
| Damper controller | |||
| SimpleController | damController | Buildings.Controls.OBC.CDL.T... | Type of damper position controller |
| Real | kDam | 0.1 | Gain of controller |
| Time | TiDam | 120 | Time constant of integrator block [s] |
| Time | TdDam | 60 | Time constant of derivative block [s] |
Connectors
| Type | Name | Description |
|---|---|---|
| input RealInput | TRooHeaSet | Setpoint temperature for room for heating [K] |
| input RealInput | TRooCooSet | Setpoint temperature for room for cooling [K] |
| input RealInput | TRoo | Measured room temperature [K] |
| input RealInput | VDis_flow | Measured primary discharge airflow rate [m3/s] |
| output RealOutput | yDam | Signal for VAV damper |
| output RealOutput | yVal | Signal for heating coil valve |
Modelica definition
block RoomVAV "Controller for room VAV box"
extends Modelica.Blocks.Icons.Block;
parameter Boolean have_preIndDam = true
"True: the terminal box has pressure independent damper";
parameter Real ratVFloMin(final unit="1") = 0.3
"Minimum airflow set point (ratio to nominal)";
parameter Real ratVFloHea(final unit="1") = ratVFloMin
"Heating airflow set point (ratio to nominal)";
parameter Modelica.Units.SI.VolumeFlowRate V_flow_nominal(min=0)=0.1
"Norminal air volume flow rate";
parameter Buildings.Controls.OBC.CDL.Types.SimpleController cooController=
Buildings.Controls.OBC.CDL.Types.SimpleController.PI "Type of controller";
parameter Real kCoo=0.1 "Gain of controller";
parameter Modelica.Units.SI.Time TiCoo=120
"Time constant of integrator block";
parameter Modelica.Units.SI.Time TdCoo=60 "Time constant of derivative block";
parameter Buildings.Controls.OBC.CDL.Types.SimpleController heaController=
Buildings.Controls.OBC.CDL.Types.SimpleController.PI "Type of controller";
parameter Real kHea=0.1 "Gain of controller";
parameter Modelica.Units.SI.Time TiHea=120
"Time constant of integrator block";
parameter Modelica.Units.SI.Time TdHea=60 "Time constant of derivative block";
parameter Buildings.Controls.OBC.CDL.Types.SimpleController damController=
Buildings.Controls.OBC.CDL.Types.SimpleController.PI "Type of damper position controller";
parameter Real kDam=0.1 "Gain of controller";
parameter Modelica.Units.SI.Time TiDam=120
"Time constant of integrator block";
parameter Modelica.Units.SI.Time TdDam=60 "Time constant of derivative block";
Buildings.Controls.OBC.CDL.Interfaces.RealInput TRooHeaSet(
final quantity="ThermodynamicTemperature",
final unit = "K",
displayUnit = "degC")
"Setpoint temperature for room for heating";
Buildings.Controls.OBC.CDL.Interfaces.RealInput TRooCooSet(
final quantity="ThermodynamicTemperature",
final unit = "K",
displayUnit = "degC")
"Setpoint temperature for room for cooling";
Buildings.Controls.OBC.CDL.Interfaces.RealInput TRoo(
final quantity="ThermodynamicTemperature",
final unit = "K",
displayUnit = "degC")
"Measured room temperature";
Buildings.Controls.OBC.CDL.Interfaces.RealInput VDis_flow(
final min=0,
final unit="m3/s",
final quantity="VolumeFlowRate") if not have_preIndDam
"Measured primary discharge airflow rate";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput yDam "Signal for VAV damper";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput yVal "Signal for heating coil valve";
Buildings.Controls.OBC.CDL.Reals.PID conHea(
yMax=yMax,
Td=TdHea,
yMin=yMin,
k=kHea,
Ti=TiHea,
controllerType=heaController,
Ni=10) "Controller for heating";
Buildings.Controls.OBC.CDL.Reals.PID conCoo(
yMax=yMax,
Td=TdCoo,
k=kCoo,
Ti=TiCoo,
controllerType=cooController,
yMin=yMin,
reverseActing=false) "Controller for cooling (acts on damper)";
Buildings.Controls.OBC.CDL.Reals.Line reqFlo "Required flow rate";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant cooMax(k=1)
"Cooling maximum flow";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant minFloCoo(
final k=ratVFloMin) "Minimum air flow set point";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant conOne(k=1)
"Constant 1";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant conZer(k=0)
"Constant 0";
Buildings.Controls.OBC.CDL.Reals.Hysteresis hysWitHol(
final uLow=-dTHys,
final uHigh=0)
"Output true if room temperature below heating set point";
Buildings.Controls.OBC.CDL.Reals.Subtract dTHea
"Heating loop control error";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant minFloHea(
final k=ratVFloHea) "Minimum air flow set point in heating mode";
Buildings.Controls.OBC.CDL.Reals.Switch swi
"Switch between heating and deadband air flow rate";
Buildings.Controls.OBC.CDL.Utilities.Assert assMes(message=
"The difference between cooling and heating set points must be greater than dTHys")
"Assert message";
Buildings.Controls.OBC.CDL.Reals.Subtract dTSet
"Difference between cooling and heating set points";
Buildings.Controls.OBC.CDL.Reals.GreaterThreshold greThr(t=dTHys)
"Test for overlap of heating and cooling set points ";
Buildings.Controls.OBC.CDL.Reals.PID conDam(
final yMax=yMax,
final Td=TdDam,
final yMin=yMin,
final k=kDam,
final Ti=TiDam,
final controllerType=damController,
Ni=10) if not have_preIndDam
"Damper position setpoint";
Buildings.Controls.OBC.CDL.Reals.Divide VDis_flowNor
if not have_preIndDam
"Normalized discharge volume flow rate";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant norFlo(
final k=V_flow_nominal) if not have_preIndDam
"Norminal airflow rate";
Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter gai(
final k=1)
if have_preIndDam "Dummy block to enable or disable connection";
protected
parameter Real yMax=1 "Upper limit of PID control output";
parameter Real yMin=0 "Lower limit of PID control output";
parameter Modelica.Units.SI.TemperatureDifference dTHys(final min=0) = 0.5
"Hysteresis width for switching minimum air flow rate";
equation
connect(TRooCooSet, conCoo.u_s);
connect(TRoo, conHea.u_m);
connect(TRooHeaSet, conHea.u_s);
connect(conHea.y, yVal);
connect(conZer.y, reqFlo.x1);
connect(cooMax.y, reqFlo.f2);
connect(conOne.y, reqFlo.x2);
connect(conCoo.y, reqFlo.u);
connect(TRoo, conCoo.u_m);
connect(TRooHeaSet, dTHea.u1);
connect(dTHea.y, hysWitHol.u);
connect(TRoo, dTHea.u2);
connect(minFloCoo.y, swi.u3);
connect(minFloHea.y, swi.u1);
connect(hysWitHol.y, swi.u2);
connect(swi.y, reqFlo.f1);
connect(TRooCooSet, dTSet.u1);
connect(TRooHeaSet, dTSet.u2);
connect(dTSet.y, greThr.u);
connect(greThr.y, assMes.u);
connect(reqFlo.y, conDam.u_s);
connect(VDis_flow, VDis_flowNor.u1);
connect(norFlo.y, VDis_flowNor.u2);
connect(VDis_flowNor.y, conDam.u_m);
connect(conDam.y, yDam);
connect(reqFlo.y, gai.u);
connect(gai.y, yDam);
end RoomVAV;
Buildings.Examples.VAVReheat.BaseClasses.Controls.State
Block that outputs the mode if the state is active, or zero otherwise
Information
Extends from Modelica.StateGraph.StepWithSignal (Ordinary step (= step that is not active when simulation starts). Connector 'active' is true when the step is active).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| OperationModes | mode | Enter enumeration of mode |
Connectors
| Type | Name | Description |
|---|---|---|
| Step_in | inPort[nIn] | Vector of step input connectors |
| Step_out | outPort[nOut] | Vector of step output connectors |
| output BooleanOutput | active | |
| output IntegerOutput | y | Mode signal (=0 if not active) |
Modelica definition
model State
"Block that outputs the mode if the state is active, or zero otherwise"
extends Modelica.StateGraph.StepWithSignal(nIn=1, nOut=1);
parameter OperationModes mode "Enter enumeration of mode";
Modelica.Blocks.Interfaces.IntegerOutput y "Mode signal (=0 if not active)";
equation
y = if localActive then Integer(mode) else 0;
end State;
Buildings.Examples.VAVReheat.BaseClasses.Controls.SupplyAirTemperature
Control block for tracking the supply air temperature set point
Information
This block implements the control logic for the supply air temperature, as described in the control sequence VAV 2A2-21232 of the Sequences of Operation for Common HVAC Systems (ASHRAE, 2006).
The heating coil valve, outdoor air damper, and cooling coil valve are modulated in sequence to maintain the supply air temperature set point. A deadband between heating and economizer cooling is also modeled.
Note that the economizer lockout when the outdoor air temperature is higher than the return air temperature is implemented in Buildings.Examples.VAVReheat.BaseClasses.Controls.Economizer.
References
ASHRAE. Sequences of Operation for Common HVAC Systems. ASHRAE, Atlanta, GA, 2006.
Extends from Modelica.Blocks.Icons.Block (Basic graphical layout of input/output block).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Boolean | have_heating | true | Set to true for heating and cooling functions (false for cooling only) |
| SimpleController | controllerType | Buildings.Controls.OBC.CDL.T... | Type of controller |
| Real | k | 0.01 | Gain of controller |
| Time | Ti | 120 | Time constant of integrator block [s] |
| Time | Td | 0.1 | Time constant of derivative block [s] |
Connectors
| Type | Name | Description |
|---|---|---|
| input BooleanInput | uEna | Signal enabling set point tracking |
| input RealInput | TSup | Supply air temperature measurement [K] |
| input RealInput | TSupSet | Supply air temperature set point [K] |
| output RealOutput | yHea | Control signal for heating coil valve [1] |
| output RealOutput | yOA | Control signal for outdoor air damper [1] |
| output RealOutput | yCoo | Control signal for cooling coil valve [1] |
Modelica definition
block SupplyAirTemperature
"Control block for tracking the supply air temperature set point"
extends Modelica.Blocks.Icons.Block;
parameter Boolean have_heating = true
"Set to true for heating and cooling functions (false for cooling only)";
parameter Buildings.Controls.OBC.CDL.Types.SimpleController controllerType=
Buildings.Controls.OBC.CDL.Types.SimpleController.PI "Type of controller";
parameter Real k(min=0) = 0.01 "Gain of controller";
parameter Modelica.Units.SI.Time Ti(min=Buildings.Controls.OBC.CDL.Constants.small)=
120 "Time constant of integrator block";
parameter Modelica.Units.SI.Time Td(min=0) = 0.1
"Time constant of derivative block";
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput uEna
"Signal enabling set point tracking";
Buildings.Controls.OBC.CDL.Interfaces.RealInput TSup(
final unit="K",
displayUnit="degC")
"Supply air temperature measurement";
Buildings.Controls.OBC.CDL.Interfaces.RealInput TSupSet(
final unit="K",
displayUnit="degC")
"Supply air temperature set point";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput yHea(
final unit="1") if have_heating
"Control signal for heating coil valve";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput yOA(final unit="1")
"Control signal for outdoor air damper";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput yCoo(final unit="1")
"Control signal for cooling coil valve";
Buildings.Controls.OBC.CDL.Reals.PIDWithReset con(
final controllerType=controllerType,
final k=k,
final Ti=Ti,
final Td=Td,
final yMax=1,
final yMin=if have_heating then -1 else 0,
y_reset=if have_heating then limSupHea.k else limInfOA.k,
u_s(
final unit="K",
displayUnit="degC"),
u_m(
final unit="K",
displayUnit="degC"))
"Supply temperature controller";
Buildings.Controls.OBC.CDL.Reals.Line mapHea if have_heating
"Mapping function for actuating the heating coil valve ";
Buildings.Controls.OBC.CDL.Reals.Line mapOA
"Mapping function for actuating the outdoor air damper";
Buildings.Controls.OBC.CDL.Reals.Line mapCoo
"Mapping function for actuating the cooling coil valve";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant limInfHea(k=-1)
"Inferior limit of the control signal for heating coil control ";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant limSupHea(k=-0.5)
"Superior limit of the control signal for heating coil control ";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant limInfOA(k=0)
"Inferior limit of the control signal for outdoor air damper control ";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant limSupOA(k=0.5)
"Superior limit of the control signal for outdoor air damper control ";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant limSupCoo(k=1)
"Superior limit of the control signal for cooling coil control ";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant zero(k=0) "Zero";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant one(k=1) "one";
Buildings.Controls.OBC.CDL.Reals.Switch swiHea if have_heating
"Switch to close heating coil valve";
Buildings.Controls.OBC.CDL.Reals.Switch swiCoo
"Switch to close cooling coil valve";
Buildings.Controls.OBC.CDL.Reals.Switch swiOA
"Switch to close outdoor air damper";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant limInfCoo(
k=limSupOA.k)
"Inferior limit of the control signal for cooling coil control ";
equation
connect(TSup, con.u_s);
connect(TSupSet, con.u_m);
connect(con.y, mapOA.u);
connect(con.y, mapCoo.u);
connect(con.y, mapHea.u);
connect(limInfHea.y, mapHea.x1);
connect(limSupHea.y, mapHea.x2);
connect(limInfOA.y, mapOA.x1);
connect(limSupOA.y, mapOA.x2);
connect(limSupCoo.y, mapCoo.x2);
connect(one.y, mapCoo.f2);
connect(zero.y, mapHea.f2);
connect(one.y, mapOA.f2);
connect(zero.y, mapOA.f1);
connect(one.y, mapHea.f1);
connect(zero.y, mapCoo.f1);
connect(swiHea.y, yHea);
connect(mapHea.y, swiHea.u1);
connect(mapCoo.y, swiCoo.u1);
connect(zero.y, swiHea.u3);
connect(zero.y, swiCoo.u3);
connect(swiOA.y, yOA);
connect(mapOA.y, swiOA.u1);
connect(zero.y, swiOA.u3);
connect(uEna, swiCoo.u2);
connect(uEna, swiOA.u2);
connect(uEna, swiHea.u2);
connect(swiCoo.y, yCoo);
connect(limInfCoo.y, mapCoo.x1);
connect(uEna, con.trigger);
end SupplyAirTemperature;
Buildings.Examples.VAVReheat.BaseClasses.Controls.SupplyAirTemperatureSetpoint
Block computing the supply air temperature set point based on the operation mode
Information
This block computes the supply air temperature set point
based on the actual operating mode.
The default set point values are taken from the control sequence
VAV 2A2-21232 of the Sequences of Operation for
Common HVAC Systems (ASHRAE, 2006).
| Operating mode | Set point value [C] |
|---|---|
| Occupied | 12 |
| Unoccupied off | 12 |
| Unoccupied, night set back | 35 |
| Unoccupied, warm-up | 35 |
| Unoccupied, pre-cool | 12 |
| Safety | 7 |
References
ASHRAE. Sequences of Operation for Common HVAC Systems. ASHRAE, Atlanta, GA, 2006.
Extends from Modelica.Blocks.Icons.Block (Basic graphical layout of input/output block).
Connectors
| Type | Name | Description |
|---|---|---|
| ControlBus | controlBus | |
| output RealOutput | TSet | Supply air temperature set point [K] |
Modelica definition
block SupplyAirTemperatureSetpoint
"Block computing the supply air temperature set point based on the operation mode"
extends Modelica.Blocks.Icons.Block;
BaseClasses.Controls.ControlBus controlBus;
Buildings.Controls.OBC.CDL.Interfaces.RealOutput TSet(
final unit="K",
displayUnit="degC")
"Supply air temperature set point";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant TSetVal[6](k={12,12,35,
35,12,7} .+ 273.15) "Set point values for each operating mode";
Modelica.Blocks.Routing.IntegerPassThrough mode;
Modelica.Blocks.Sources.RealExpression ext(y=TSetVal[mode.y].y)
"Extract set point value corresponding to actual mode";
equation
connect(TSet, controlBus.TAirSupSet);
connect(controlBus.controlMode, mode.u);
connect(ext.y, TSet);
end SupplyAirTemperatureSetpoint;
Buildings.Examples.VAVReheat.BaseClasses.Controls.SystemHysteresis
Block that applies hysteresis and a minimum on timer to a control signal
Information
Block that ensure that the system runs for a minimum time once it is switched on.
Connectors
| Type | Name | Description |
|---|---|---|
| input RealInput | u | Control signal |
| output RealOutput | y | Real output signal |
| output RealOutput | yPum | Control signal for pump |
| input BooleanInput | sysOn | System on signal, set for example to true if fan is on |
Modelica definition
model SystemHysteresis
"Block that applies hysteresis and a minimum on timer to a control signal"
Buildings.Controls.OBC.CDL.Interfaces.RealInput u "Control signal";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput y "Real output signal";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput yPum
"Control signal for pump";
Buildings.Controls.OBC.CDL.Reals.GreaterThreshold greThr(
t=0.1,
h=0.09)
"Threshold to switch on system";
Buildings.Controls.OBC.CDL.Reals.Switch swi "Switch for control signal";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant con(final k=0)
"Zero output signal";
Buildings.Controls.OBC.CDL.Conversions.BooleanToReal booToRea
"Switch for pump control signal";
Buildings.Controls.OBC.CDL.Logical.TrueFalseHold truFalHol1(
trueHoldDuration(displayUnit="h") = 14400,
final falseHoldDuration=0)
"Keep pump running at least for trueHoldDuration";
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput sysOn
"System on signal, set for example to true if fan is on";
Buildings.Controls.OBC.CDL.Reals.Switch swiSysOff
"Switch to overide if system is off";
Buildings.Controls.OBC.CDL.Reals.Switch swiSysOff1
"Switch to overide if system is off";
Buildings.Controls.OBC.CDL.Logical.TrueDelay truDel(final delayTime=30)
"Short delay to ignore spike inputs that trigger pump to operate";
equation
connect(greThr.u, u);
connect(swi.u1, u);
connect(con.y, swi.u3);
connect(truFalHol1.y, swi.u2);
connect(truFalHol1.y, booToRea.u);
connect(sysOn, swiSysOff.u2);
connect(swiSysOff.y, y);
connect(swi.y, swiSysOff.u1);
connect(con.y, swiSysOff.u3);
connect(swiSysOff1.y, yPum);
connect(booToRea.y, swiSysOff1.u1);
connect(swiSysOff1.u3, con.y);
connect(sysOn, swiSysOff1.u2);
connect(truFalHol1.u, truDel.y);
connect(greThr.y, truDel.u);
end SystemHysteresis;