Buildings.Examples.VAVReheat.Controls
Package with controller models
Information
Extends from Modelica.Icons.VariantsPackage (Icon for package containing variants).
Package Content
Name | Description |
---|---|
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Empty control bus that is adapted to the signals connected to it |
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Set point scheduler for cooling coil |
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Computes the duct static pressure setpoint |
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Controller for economizer |
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Controller for economizer mixed air temperature |
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Controller for fan revolution |
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Mixed air temperature setpoint for economizer |
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Finite State Machine for the operational modes |
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Enumeration for modes of operation |
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Outputs true when precooling should start |
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Set point scheduler for room temperature |
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Controller for room VAV box |
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Block that outputs the mode if the state is active, or zero otherwise |
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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.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
Buildings.Examples.VAVReheat.Controls.CoolingCoilTemperatureSetpoint
Set point scheduler for cooling coil
Information
Extends from Modelica.Blocks.Icons.Block (Basic graphical layout of input/output block).
Parameters
Type | Name | Default | Description |
---|---|---|---|
Temperature | TCooOn | 273.15 + 12 | Cooling setpoint during on [K] |
Temperature | TCooOff | 273.15 + 30 | Cooling setpoint during off [K] |
Connectors
Type | Name | Description |
---|---|---|
input RealInput | TSetHea | Set point for heating coil [K] |
ControlBus | controlBus | |
output RealOutput | TSet | Temperature set point [K] |
Modelica definition
Buildings.Examples.VAVReheat.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 |
input RealInput | TOut | Outside air temperature |
Modelica definition
Buildings.Examples.VAVReheat.Controls.Economizer
Controller for economizer
Information
This is a controller for an economizer with that adjust the outside air dampers to meet the set point for the mixing air, taking into account the minimum outside air requirement and an override for freeze protection.
Parameters
Type | Name | Default | Description |
---|---|---|---|
Temperature | TFreSet | 277.15 | Lower limit for mixed air temperature for freeze protection [K] |
TemperatureDifference | dT | 1 | Temperture offset to activate economizer [K] |
VolumeFlowRate | VOut_flow_min | Minimum outside air volume flow rate [m3/s] | |
Real | k | 1 | Gain of controller |
Time | Ti | Time constant of integrator block [s] |
Connectors
Type | Name | Description |
---|---|---|
input RealInput | TSupHeaSet | Supply temperature setpoint for heating |
input RealInput | TSupCooSet | Supply temperature setpoint for cooling |
input RealInput | TMix | Measured mixed air temperature |
ControlBus | controlBus | |
input RealInput | VOut_flow | Measured outside air flow rate |
input RealInput | TRet | Return air temperature |
output RealOutput | yOA | Control signal for outside air damper |
output RealOutput | yRet | Control signal for return air damper |
Modelica definition
Buildings.Examples.VAVReheat.Controls.EconomizerTemperatureControl
Controller for economizer mixed air temperature
Information
This controller outputs the control signal for the outside
air damper in order to regulate the mixed air temperature
TMix
.
Implementation
If the control error Tmix,set - Tmix < 0,
then more outside air is needed provided that Tout < Tret,
where
Tout is the outside air temperature and
Tret is the return air temperature.
However, if Tout ≥ Tret,
then less outside air is needed.
Hence, the control gain need to switch sign depending on this difference.
This is accomplished by taking the difference between these signals,
and then switching the input of the controller.
A hysteresis is used to avoid chattering, for example if
TRet
has numerical noise in the simulation, or
measurement error in a real application.
Extends from Modelica.Blocks.Icons.Block (Basic graphical layout of input/output block).
Parameters
Type | Name | Default | Description |
---|---|---|---|
Real | k | 1 | Gain of controller |
Time | Ti | Time constant of integrator block [s] |
Connectors
Type | Name | Description |
---|---|---|
output RealOutput | yOA | Control signal for outside air damper |
input RealInput | TRet | Return air temperature |
input RealInput | TOut | Outside air temperature |
input RealInput | TMix | Mixed air temperature |
input RealInput | TMixSet | Setpoint for mixed air temperature |
Modelica definition
Buildings.Examples.VAVReheat.Controls.FanVFD
Controller for fan revolution
Information
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.Simpl... | 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
Buildings.Examples.VAVReheat.Controls.MixedAirTemperatureSetpoint
Mixed air temperature setpoint for economizer
Information
Extends from Modelica.Blocks.Icons.Block (Basic graphical layout of input/output block).
Connectors
Type | Name | Description |
---|---|---|
input RealInput | TSupHeaSet | Supply temperature setpoint for heating |
input RealInput | TSupCooSet | Supply temperature setpoint for cooling |
ControlBus | controlBus | |
output RealOutput | TSet | Mixed air temperature setpoint |
Modelica definition
Buildings.Examples.VAVReheat.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] |
Temperature | TSetHeaCoiOut | 303.15 | Set point for air outlet temperature at central heating coil [K] |
Connectors
Type | Name | Description |
---|---|---|
ControlBus | cb | |
output BooleanOutput | yFan | True if the fans are to be switched on |
Modelica definition
Buildings.Examples.VAVReheat.Controls.OperationModes
Enumeration for modes of operation
Modelica definition
Buildings.Examples.VAVReheat.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
Buildings.Examples.VAVReheat.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
Buildings.Examples.VAVReheat.Controls.RoomVAV
Controller for room VAV box
Information
Controller for terminal VAV box with hot water reheat and pressure independent damper.
It was implemented according to
[Advanced Variabled Air Volume System Design Guide], single maximum VAV reheat box
control.
The damper control signal yDam
corresponds to the discharge air flow rate
set-point, normalized to the nominal value.
-
In cooling demand, the damper control signal
yDam
is modulated between a minimum valueratVFloMin
(typically between 30% and 50%) and 1 (corresponding to the nominal value). The control signal for the reheat coil valveyVal
is 0 (corresponding to the valve fully closed). -
In heating demand, the damper control signal
yDam
is fixed at the minimum valueratVFloMin
. The control signal for the reheat coil valveyVal
is modulated between 0 and 1 (corresponding to the valve fully open).
Extends from Modelica.Blocks.Icons.Block (Basic graphical layout of input/output block).
Parameters
Type | Name | Default | Description |
---|---|---|---|
Real | ratVFloMin | 0.3 | VAV box minimum airflow ratio to the cooling maximum flow rate, typically between 0.3 to 0.5 |
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] |
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] |
output RealOutput | yDam | Signal for VAV damper |
output RealOutput | yVal | Signal for heating coil valve |
Modelica definition
Buildings.Examples.VAVReheat.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 |
---|---|---|---|
Integer | nIn | 1 | Number of input connections |
Integer | nOut | 1 | Number of output connections |
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) |