Buildings.Fluid.HeatPumps.ModularReversible.Controls.Safety
Contains typical safety controllers for heat pumps
Information
Package with safety controls typically applied in heat pumps and chiller devices.
Extends from Modelica.Icons.Package (Icon for standard packages).
Package Content
| Name | Description |
|---|---|
 AntiFreeze
|
Model to prevent source from freezing |
| MinimalFlowRate
|
Safety control for minimum mass flow rate |
 OnOff
|
Controlls if the Safety constraints for on-time, off-time, and cycle rate |
| OperationalEnvelope
|
Indicates if the heat pump operation is within a defined envelope |
 Safety
|
Model including all safety levels |
 Data
|
Package with parameters for safety control blocks |
 Examples
|
Examples package |
 BaseClasses
|
Package with base classes for Buildings.Fluid.HeatPump.Controls.Safety |
Buildings.Fluid.HeatPumps.ModularReversible.Controls.Safety.AntiFreeze
Model to prevent source from freezing
Information
This model is used to prevent freezing of the condenser or evaporator side. A real device would shut off as well.
This models takes the minimum of the two temperatures evaporator outlet and condenser inlet. If this minimal temperature falls below the given lower boundary, the hystereses will trigger an error and cause the device to switch off.
Assumptions
This block does not check the evaporator inlet or condenser outlet temperatures because they are assumed to be always higher than the other side.Extends from BaseClasses.PartialSafetyWithCounter (Safety control which adds an error counter to the I/O).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| ThermodynamicTemperature | TAntFre | 276.15 | Limit temperature for anti freeze control [K] |
| Real | dTHys | 2 | Hysteresis interval width |
Connectors
| Type | Name | Description |
|---|---|---|
| input RealInput | ySet | Input for relative compressor speed from 0 to 1 |
| output RealOutput | yOut | Output for relative compressor speed from 0 to 1 |
| RefrigerantMachineControlBus | sigBus | Bus-connector for the heat pump |
| output IntegerOutput | err | Integer for displaying number of errors during simulation |
Modelica definition
model AntiFreeze "Model to prevent source from freezing"
extends BaseClasses.PartialSafetyWithCounter;
parameter Modelica.Units.SI.ThermodynamicTemperature TAntFre=276.15
"Limit temperature for anti freeze control";
parameter Real dTHys=2
"Hysteresis interval width";
Modelica.Blocks.Logical.Hysteresis hys(
final uLow=TAntFre,
final pre_y_start=true,
final uHigh=TAntFre + dTHys) "Hysteresis to indicate if freezing occurs";
Modelica.Blocks.Math.Min min
"Minimum of evaporator outlet and condenser inlet temperatures";
equation
connect(ySet,swiErr.u1);
connect(min.y, hys.u);
connect(sigBus.TConInMea, min.u1);
connect(sigBus.TEvaOutMea, min.u2);
connect(hys.y, booPasThr.u);
end AntiFreeze;
Buildings.Fluid.HeatPumps.ModularReversible.Controls.Safety.MinimalFlowRate
Safety control for minimum mass flow rate
Information
Safety control to prevent the device from turning on if the mass flow rate is too low in either condenser or evaporator.
Used in real devices to prevent overheating or freezing of components.
Extends from BaseClasses.PartialSafetyWithCounter (Safety control which adds an error counter to the I/O).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| MassFlowRate | mEvaMin_flow | Minimal mass flow rate in evaporator required to operate the device [kg/s] | |
| MassFlowRate | mConMin_flow | Minimal mass flow rate in condenser required to operate the device [kg/s] |
Connectors
| Type | Name | Description |
|---|---|---|
| input RealInput | ySet | Input for relative compressor speed from 0 to 1 |
| output RealOutput | yOut | Output for relative compressor speed from 0 to 1 |
| RefrigerantMachineControlBus | sigBus | Bus-connector for the heat pump |
| output IntegerOutput | err | Integer for displaying number of errors during simulation |
Modelica definition
model MinimalFlowRate "Safety control for minimum mass flow rate"
extends BaseClasses.PartialSafetyWithCounter;
parameter Modelica.Units.SI.MassFlowRate mEvaMin_flow
"Minimal mass flow rate in evaporator required to operate the device";
parameter Modelica.Units.SI.MassFlowRate mConMin_flow
"Minimal mass flow rate in condenser required to operate the device";
Modelica.Blocks.Logical.Hysteresis hysCon(
final uLow=mConMin_flow,
final uHigh=max(mConMin_flow*1.1, Modelica.Constants.eps),
final pre_y_start=false)
"Check if condenser mass flow rate is high enough";
Modelica.Blocks.Logical.Hysteresis hysEva(
final uLow=mEvaMin_flow,
final uHigh=max(mEvaMin_flow*1.1, Modelica.Constants.eps),
final pre_y_start=false)
"Check if evaporator mass flow rate is high enough";
Modelica.Blocks.Logical.And and1
"Both condenser and evaporator have sufficient flow";
equation
connect(hysCon.y, and1.u1);
connect(hysEva.y, and1.u2);
connect(and1.y, booPasThr.u);
connect(hysEva.u, sigBus.mEvaMea_flow);
connect(hysCon.u, sigBus.mConMea_flow);
connect(ySet, swiErr.u1);
end MinimalFlowRate;
Buildings.Fluid.HeatPumps.ModularReversible.Controls.Safety.OnOff
Controlls if the Safety constraints for on-time, off-time, and cycle rate
Information
Checks if the ySet value is legal by checking if
the device can either be turned on or off,
depending on which state it was in.
The output yOut equals ySet, if the device
-
is on and
ySetis greater thanySet_small -
or is off and
ySetis 0 - or is on and should turn off, and exceeds the minimal on-time (if active)
- or is off and should turn on, and does neither exceed the maximal cycle rate (if active) nor violates the minimal off-time (if active).
If the device is on and should turn off, but does not exceed
the minimal on-time (if active), yOut
equals min(ySet, ySetMin).
If the device is off and should turn on, but exceeds the maximal
cycle rate (if active) or violates the minimal
off-time (if active), yOut equals 0.
Extends from BaseClasses.PartialSafety (Safety control with I/O).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Boolean | use_minOnTime | true | =false to ignore minimum on-time constraint |
| Time | minOnTime | Minimum on-time [s] | |
| Boolean | use_minOffTime | true | =false to ignore minimum off time constraint |
| Time | minOffTime | Minimum off time [s] | |
| Boolean | use_maxCycRat | true | =false to ignore maximal cycle rate constraint |
| Integer | maxCycRat | Maximum cycle rate | |
| Boolean | onOffMea_start | true | Start value for the on-off signal of the device, true for on |
| Real | ySet_small | Threshold for relative speed for the device to be considered on | |
| Real | ySetRed | ySet_small | Reduced relative compressor speed to allow longer on-time |
Connectors
| Type | Name | Description |
|---|---|---|
| input RealInput | ySet | Input for relative compressor speed from 0 to 1 |
| output RealOutput | yOut | Output for relative compressor speed from 0 to 1 |
| RefrigerantMachineControlBus | sigBus | Bus-connector for the heat pump |
Modelica definition
model OnOff
"Controlls if the Safety constraints for on-time, off-time, and cycle rate"
extends BaseClasses.PartialSafety;
parameter Boolean use_minOnTime=true
"=false to ignore minimum on-time constraint";
parameter Modelica.Units.SI.Time minOnTime(displayUnit="min")
"Minimum on-time";
parameter Boolean use_minOffTime=true
"=false to ignore minimum off time constraint";
parameter Modelica.Units.SI.Time minOffTime(displayUnit="min")
"Minimum off time";
parameter Boolean use_maxCycRat=true
"=false to ignore maximal cycle rate constraint";
parameter Integer maxCycRat "Maximum cycle rate";
parameter Boolean onOffMea_start=true
"Start value for the on-off signal of the device, true for on";
parameter Real ySet_small
"Threshold for relative speed for the device to be considered on";
parameter Real ySetRed=ySet_small
"Reduced relative compressor speed to allow longer on-time";
Modelica.Blocks.Logical.Hysteresis ySetOn(
final pre_y_start=onOffMea_start,
final uHigh=ySet_small,
final uLow=ySet_small/2) "=true if device is set on";
Modelica.Blocks.Routing.BooleanPassThrough isAblToTurOff(
y(start=true, fixed=true))
"=true if the device is allowed to turn off, else false";
Modelica.Blocks.Logical.Pre preOnOff(final pre_u_start=onOffMea_start)
"On off signal of previous time step";
Buildings.Fluid.HeatPumps.ModularReversible.Controls.Safety.BaseClasses.CycleRateBoundary
cycRatBou(final maxCycRat=maxCycRat, final delTim=3600) if use_maxCycRat
"Check cycle rate violations";
Buildings.Fluid.HeatPumps.ModularReversible.Controls.Safety.BaseClasses.OnPastThreshold
locTimCtr(
final minOnTime=minOffTime) if use_minOffTime
"Check if device should be locked";
Modelica.Blocks.Logical.Not notIsOn "=true if device is off";
Buildings.Fluid.HeatPumps.ModularReversible.Controls.Safety.BaseClasses.OnPastThreshold
runTimCtr(
final minOnTime=minOnTime) if use_minOnTime "Check if device needs to run";
Modelica.Blocks.Logical.And andIsAblToTurOn(
y(start=true, fixed=true))
"=false to lock the device off";
Modelica.Blocks.Sources.BooleanConstant booConstCycRat(final k=true)
if not use_maxCycRat "Constant value for disabled option";
Modelica.Blocks.Sources.BooleanConstant booConstLocTim(final k=true)
if not use_minOffTime "Constant value for disabled option";
Modelica.Blocks.Sources.BooleanConstant booConstRunTim(final k=true)
if not use_minOnTime "Constant value for disabled option";
Modelica.Blocks.Logical.Not notSetOn "Device is not set to turn on";
Modelica.Blocks.Logical.And andTurOff
"Check if device is on and is set to be turned off";
Modelica.Blocks.Logical.And andTurOn
"Check if device is off and is set to be turned on";
Modelica.Blocks.Logical.And andStaOn
"=true if the device is on and wants to stay on";
Modelica.Blocks.Logical.And andStaOff
"=true if the device is off and wants to stay off";
BaseClasses.OnOffFuzzyLogic onOffFuzLog(ySetRed=ySetRed)
"Fuzzy logic to device for output";
equation
connect(preOnOff.y, cycRatBou.u);
connect(preOnOff.y, notIsOn.u);
connect(notIsOn.y, locTimCtr.u);
connect(runTimCtr.u, preOnOff.y);
connect(locTimCtr.y, andIsAblToTurOn.u1);
connect(cycRatBou.y, andIsAblToTurOn.u2);
connect(booConstCycRat.y, andIsAblToTurOn.u2);
connect(ySetOn.y, notSetOn.u);
connect(notSetOn.y, andTurOff.u2);
connect(preOnOff.y, andTurOff.u1);
connect(ySetOn.y, andTurOn.u2);
connect(notIsOn.y, andTurOn.u1);
connect(booConstLocTim.y, andIsAblToTurOn.u1);
connect(preOnOff.u, sigBus.onOffMea);
connect(ySetOn.u, ySet);
connect(andStaOn.u1, ySetOn.y);
connect(andStaOn.u2, preOnOff.y);
connect(andStaOff.u1, notIsOn.y);
connect(andStaOff.u2, notSetOn.y);
connect(isAblToTurOff.u, runTimCtr.y);
connect(booConstRunTim.y, isAblToTurOff.u);
connect(onOffFuzLog.yOut, yOut);
connect(onOffFuzLog.ySet, ySet);
connect(onOffFuzLog.staOff, andStaOff.y);
connect(onOffFuzLog.staOn, andStaOn.y);
connect(onOffFuzLog.isAblToTurOff, isAblToTurOff.y);
connect(andIsAblToTurOn.y, onOffFuzLog.isAblToTurOn);
connect(onOffFuzLog.turOff, andTurOff.y);
connect(onOffFuzLog.turOn, andTurOn.y);
end OnOff;
Buildings.Fluid.HeatPumps.ModularReversible.Controls.Safety.OperationalEnvelope
Indicates if the heat pump operation is within a defined envelope
Information
Model to check if the operating conditions of a heat pump are inside the given boundaries. If not, the heat pump or chiller will switch off.
Read the documentation of Buildings.Fluid.HeatPumps.ModularReversible.Controls.Safety.BaseClasses.PartialOperationalEnvelope for more information.
Extends from BaseClasses.PartialOperationalEnvelope (Indicates if the device operation is within a defined envelope).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Temperature | tabUppHea[:, 2] | Upper boundary for heating with second column as useful temperature side [K] | |
| Temperature | tabLowCoo[:, 2] | Lower boundary for cooling with second column as useful temperature side [K] | |
| TemperatureDifference | dTHys | 5 | Temperature deadband in the operational envelope [K] |
| Operational Envelope | |||
| Boolean | use_TConOutHea | true | =true to use condenser outlet temperature for envelope in heating mode, false for inlet |
| Boolean | use_TEvaOutHea | false | =true to use evaporator outlet temperature for envelope in heating mode, false for inlet |
| Boolean | use_TConOutCoo | false | =true to use useful side outlet temperature for envelope in cooling mode, false for inlet |
| Boolean | use_TEvaOutCoo | true | =true to use evaporator outlet temperature for envelope in cooling mode, false for inlet |
Connectors
| Type | Name | Description |
|---|---|---|
| input RealInput | ySet | Input for relative compressor speed from 0 to 1 |
| output RealOutput | yOut | Output for relative compressor speed from 0 to 1 |
| RefrigerantMachineControlBus | sigBus | Bus-connector for the heat pump |
| output IntegerOutput | err | Integer for displaying number of errors during simulation |
Modelica definition
model OperationalEnvelope
"Indicates if the heat pump operation is within a defined envelope"
extends BaseClasses.PartialOperationalEnvelope;
equation
if use_TConOutHea then
connect(bouMapHea.TUseSid, sigBus.TConOutMea);
else
connect(bouMapHea.TUseSid, sigBus.TConInMea);
end if;
if use_TEvaOutCoo then
connect(bouMapCoo.TAmbSid, sigBus.TEvaOutMea);
else
connect(bouMapCoo.TAmbSid, sigBus.TEvaInMea);
end if;
if use_TEvaOutHea then
connect(bouMapHea.TAmbSid, sigBus.TEvaOutMea);
else
connect(bouMapHea.TAmbSid, sigBus.TEvaInMea);
end if;
if use_TConOutCoo then
connect(bouMapCoo.TUseSid, sigBus.TConOutMea);
else
connect(bouMapCoo.TUseSid, sigBus.TConInMea);
end if;
connect(swiHeaCoo.u2, sigBus.hea);
end OperationalEnvelope;
Buildings.Fluid.HeatPumps.ModularReversible.Controls.Safety.Safety
Model including all safety levels
Information
Aggregation of the four main safety controls of a refrigerant machine (heat pump or chiller).
The order is based on the relevance to a real system. Antifreeze control and mininmum flow rate control are put last because of the relevance for the simulation. If the medium temperature falls below or rises above the critical values, the simulation will fail.
All used functions are optional. See the used models for more information on each safety function:
- Buildings.Fluid.HeatPumps.ModularReversible.Controls.Safety.OnOff
- Buildings.Fluid.HeatPumps.ModularReversible.Controls.Safety.OperationalEnvelope
- Buildings.Fluid.HeatPumps.ModularReversible.Controls.Safety.AntiFreeze
- Buildings.Fluid.HeatPumps.ModularReversible.Controls.Safety.MinimalFlowRate
Extends from BaseClasses.PartialSafety (Safety control with I/O).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Real | ySet_small | Threshold for relative speed for the device to be considered on | |
| Generic | safCtrPar | redeclare parameter Building... | Safety control parameters |
| OperationalEnvelope | opeEnv | redeclare Buildings.Fluid.He... | Block for operational envelope |
| Mass flow rates | |||
| MassFlowRate | mEva_flow_nominal | Nominal mass flow rate in evaporator medium [kg/s] | |
| MassFlowRate | mCon_flow_nominal | Nominal mass flow rate in condenser medium [kg/s] | |
Connectors
| Type | Name | Description |
|---|---|---|
| input RealInput | ySet | Input for relative compressor speed from 0 to 1 |
| output RealOutput | yOut | Output for relative compressor speed from 0 to 1 |
| RefrigerantMachineControlBus | sigBus | Bus-connector for the heat pump |
| output IntegerOutput | opeEnvErr | Number of errors from violating the operational envelope |
| output IntegerOutput | antFreErr | Number of errors from antifreeze control |
| output IntegerOutput | minFlowErr | Number of errors from violating minimum flow rates |
Modelica definition
model Safety "Model including all safety levels"
extends BaseClasses.PartialSafety;
parameter Modelica.Units.SI.MassFlowRate mEva_flow_nominal
"Nominal mass flow rate in evaporator medium";
parameter Modelica.Units.SI.MassFlowRate mCon_flow_nominal
"Nominal mass flow rate in condenser medium";
parameter Real ySet_small
"Threshold for relative speed for the device to be considered on";
replaceable parameter Buildings.Fluid.HeatPumps.ModularReversible.Controls.Safety.Data.Generic
safCtrPar constrainedby Buildings.Fluid.HeatPumps.ModularReversible.Controls.Safety.Data.Generic
"Safety control parameters";
replaceable Buildings.Fluid.HeatPumps.ModularReversible.Controls.Safety.OperationalEnvelope
opeEnv if safCtrPar.use_opeEnv constrainedby Buildings.Fluid.HeatPumps.ModularReversible.Controls.Safety.BaseClasses.PartialOperationalEnvelope
(
final use_TConOutHea=safCtrPar.use_TConOutHea,
final use_TEvaOutHea=safCtrPar.use_TEvaOutHea,
final use_TConOutCoo=safCtrPar.use_TConOutCoo,
final use_TEvaOutCoo=safCtrPar.use_TEvaOutCoo,
final tabUppHea=safCtrPar.tabUppHea,
final tabLowCoo=safCtrPar.tabLowCoo,
final dTHys=safCtrPar.dTHysOpeEnv) "Block for operational envelope";
Buildings.Fluid.HeatPumps.ModularReversible.Controls.Safety.OnOff onOffCtr(
final minOnTime=safCtrPar.minOnTime,
final minOffTime=safCtrPar.minOffTime,
final use_minOnTime=safCtrPar.use_minOnTime,
final use_minOffTime=safCtrPar.use_minOffTime,
final use_maxCycRat=safCtrPar.use_maxCycRat,
final maxCycRat=safCtrPar.maxCycRat,
final onOffMea_start=safCtrPar.onOffMea_start,
final ySet_small=ySet_small,
final ySetRed=safCtrPar.ySetRed) if safCtrPar.use_minOnTime or safCtrPar.use_minOffTime
or safCtrPar.use_maxCycRat "On off control block";
Buildings.Fluid.HeatPumps.ModularReversible.Controls.Safety.AntiFreeze antFre(final TAntFre=
safCtrPar.TAntFre, final dTHys=safCtrPar.dTHysAntFre)
if safCtrPar.use_antFre "Antifreeze control";
Modelica.Blocks.Interfaces.IntegerOutput opeEnvErr if safCtrPar.use_opeEnv
"Number of errors from violating the operational envelope";
Modelica.Blocks.Interfaces.IntegerOutput antFreErr if safCtrPar.use_antFre
"Number of errors from antifreeze control";
Buildings.Fluid.HeatPumps.ModularReversible.Controls.Safety.MinimalFlowRate
minVolFloRatSaf(final mEvaMin_flow=safCtrPar.r_mEvaMinPer_flow*
mEva_flow_nominal, final mConMin_flow=safCtrPar.r_mConMinPer_flow*
mCon_flow_nominal) if safCtrPar.use_minFlowCtr
"Block to ensure minimal flow rates";
Modelica.Blocks.Interfaces.IntegerOutput minFlowErr
if safCtrPar.use_minFlowCtr
"Number of errors from violating minimum flow rates";
Modelica.Blocks.Routing.RealPassThrough reaPasThrOnOff if not (safCtrPar.use_minOnTime
or safCtrPar.use_minOffTime or safCtrPar.use_maxCycRat)
"No on off control";
Modelica.Blocks.Routing.RealPassThrough reaPasThrOpeEnv
if not safCtrPar.use_opeEnv "No operational envelope control";
Modelica.Blocks.Routing.RealPassThrough reaPasThrAntFre
if not safCtrPar.use_antFre "No antifreeze control";
Modelica.Blocks.Routing.RealPassThrough reaPasThrMinVolRat
if not safCtrPar.use_minFlowCtr "No minimum flow rate control";
equation
connect(sigBus, onOffCtr.sigBus);
connect(sigBus, opeEnv.sigBus);
connect(sigBus, antFre.sigBus);
connect(antFre.err, antFreErr);
connect(opeEnv.err, opeEnvErr);
connect(minVolFloRatSaf.yOut, yOut);
connect(sigBus, minVolFloRatSaf.sigBus);
connect(minVolFloRatSaf.err, minFlowErr);
connect(reaPasThrOnOff.y, reaPasThrOpeEnv.u);
connect(reaPasThrOpeEnv.y, reaPasThrAntFre.u);
connect(reaPasThrAntFre.y, reaPasThrMinVolRat.u);
connect(reaPasThrMinVolRat.y, yOut);
connect(onOffCtr.yOut, opeEnv.ySet);
connect(opeEnv.yOut, antFre.ySet);
connect(antFre.yOut, minVolFloRatSaf.ySet);
connect(antFre.yOut, reaPasThrMinVolRat.u);
connect(reaPasThrAntFre.y, minVolFloRatSaf.ySet);
connect(opeEnv.yOut, reaPasThrAntFre.u);
connect(reaPasThrOpeEnv.y, antFre.ySet);
connect(onOffCtr.yOut, reaPasThrOpeEnv.u);
connect(reaPasThrOnOff.y, opeEnv.ySet);
connect(ySet, onOffCtr.ySet);
connect(ySet, reaPasThrOnOff.u);
end Safety;