Description: "Package with models for discrete time controls"

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## Buildings.Controls.Continuous

Package with models for discrete time controls

### Information

This package contains components models for continuous time controls. For additional models, see also Modelica.Blocks.Discrete.

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

### Package Content

Name | Description
--- | ---
LimPID | P, PI, PD, and PID controller with limited output, anti-windup compensation and setpoint weighting
NumberOfRequests | Outputs the number of signals that are above/below a certain threshold
OffTimer | Records the time since the input changed to false
PIDHysteresis | PID controller with anti-windup, output limiter and output hysteresis
PIDHysteresisTimer | PID controller with anti-windup, hysteresis and timer to prevent short cycling
SignalRanker | Ranks output signals such that y[i] >= y[i+1]
Examples | Collection of models that illustrate model use and test models

## Buildings.Controls.Continuous.LimPID

P, PI, PD, and PID controller with limited output, anti-windup compensation and setpoint weighting

### Information

This model is identical to Modelica.Blocks.Continuous.LimPID except that it can be configured to have a reverse action.

If the parameter `reverseAction=false` (the default), then `u_m < u_s` increases the controller output, otherwise the controller output is decreased. Thus,

- for a heating coil with a two-way valve, set `reverseAction = false`,
- for a cooling coils with a two-way valve, set `reverseAction = true`.

Extends from Modelica.Blocks.Continuous.LimPID (P, PI, PD, and PID controller with limited output, anti-windup compensation and setpoint weighting).

### Parameters

Type | Name | Default | Description
--- | --- | --- | ---
SimpleController | controllerType | .Modelica.Blocks.Types.Simpl... | Type of controller
Real | k | 1 | Gain of controller [1]
Time | Ti | 0.5 | Time constant of Integrator block [s]
Time | Td | 0.1 | Time constant of Derivative block [s]
Real | yMax | 1 | Upper limit of output
Real | yMin | 0 | Lower limit of output
Real | wp | 1 | Set-point weight for Proportional block (0..1)
Real | wd | 0 | Set-point weight for Derivative block (0..1)
Real | Ni | 0.9 | Ni*Ti is time constant of anti-windup compensation
Real | Nd | 10 | The higher Nd, the more ideal the derivative block
Boolean | reverseAction | false | Set to true for throttling the water flow rate through a cooling coil controller
Initialization
InitPID | initType | .Modelica.Blocks.Types.InitP... | Type of initialization (1: no init, 2: steady state, 3: initial state, 4: initial output)
Boolean | limitsAtInit | true | = false, if limits are ignored during initialization
Real | xi_start | 0 | Initial or guess value value for integrator output (= integrator state)
Real | xd_start | 0 | Initial or guess value for state of derivative block
Real | y_start | 0 | Initial value of output
Advanced
Boolean | strict | false | = true, if strict limits with noEvent(..)

### Connectors

Type | Name | Description
--- | --- | ---
input RealInput | u_s | Connector of setpoint input signal
input RealInput | u_m | Connector of measurement input signal
output RealOutput | y | Connector of actuator output signal

### Modelica definition

block LimPID "P, PI, PD, and PID controller with limited output, anti-windup compensation and setpoint weighting" extends Modelica.Blocks.Continuous.LimPID( addP(k1=revAct*wp, k2=-revAct), addD(k1=revAct*wd, k2=-revAct), addI(k1=revAct, k2=-revAct), yMin=0, yMax=1); parameter Boolean reverseAction = false "Set to true for throttling the water flow rate through a cooling coil controller"; protected parameter Real revAct = if reverseAction then -1 else 1; end LimPID;

## Buildings.Controls.Continuous.NumberOfRequests

Outputs the number of signals that are above/below a certain threshold

### Information

Block that outputs the number of inputs that exceed a threshold. The parameter `kind` is used to determine the kind of the inequality. The table below shows the allowed settings.

Value of parameter `kind` | Output signal incremented by 1 for each i ∈ {1, ..., nin} if
--- | ---
0 | `u[i] > threShold`
1 | `u[i] ≥ threShold`
2 | `u[i] ≤ threShold`
3 | `u[i] < threShold`

This model may be used to check how many rooms exceed a temperature threshold.

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

### Parameters

Type | Name | Default | Description
--- | --- | --- | ---
Integer | nin |  | Number of inputs
Real | threShold | 0 | Threshold
Integer | kind |  | Set to 0 for u>threShold, to 1 for >=, to 2 for <= or to 3 for <

### Connectors

Type | Name | Description
--- | --- | ---
output IntegerOutput | y | Number of input signals that violate the threshold
input RealInput | u[nin] | Input signals

### Modelica definition

block NumberOfRequests "Outputs the number of signals that are above/below a certain threshold" extends Modelica.Blocks.Icons.Block; parameter Integer nin "Number of inputs"; parameter Real threShold = 0 "Threshold"; parameter Integer kind "Set to 0 for u>threShold, to 1 for >=, to 2 for <= or to 3 for <"; Modelica.Blocks.Interfaces.IntegerOutput y "Number of input signals that violate the threshold"; Modelica.Blocks.Interfaces.RealInput u[nin] "Input signals"; algorithm y := 0; for i in 1:nin loop if kind == 0 then if u[i] > threShold then y := y+1; end if; end if; if kind == 1 then if u[i] >= threShold then y := y+1; end if; end if; if kind == 2 then if u[i] <= threShold then y := y+1; end if; end if; if kind == 3 then if u[i] < threShold then y := y+1; end if; end if; end for; end NumberOfRequests;

## Buildings.Controls.Continuous.OffTimer

Records the time since the input changed to false

### Information

Block that records the time that has elapsed since its input signal switched to false.

At the beginning of the simulation, this block outputs the time that has elapsed since the start of the simulation. Afterwards, whenever its input switches to false, the timer is reset.

Extends from Modelica.Blocks.Interfaces.partialBooleanBlockIcon (This icon will be removed in future Modelica versions, use Modelica.Blocks.Icons.PartialBooleanBlock instead.).

### Connectors

Type | Name | Description
--- | --- | ---
input BooleanInput | u | Connector of Boolean input signal
output RealOutput | y | Connector of Real output signal

### Modelica definition

model OffTimer "Records the time since the input changed to false" extends Modelica.Blocks.Interfaces.partialBooleanBlockIcon; Modelica.Blocks.Interfaces.BooleanInput u "Connector of Boolean input signal"; Modelica.Blocks.Interfaces.RealOutput y "Connector of Real output signal"; protected discrete Modelica.SIunits.Time entryTime "Time instant when u became true"; initial equation pre(entryTime) = 0; equation when (not u) then entryTime = time; end when; y = time - entryTime; end OffTimer;

## Buildings.Controls.Continuous.PIDHysteresis

PID controller with anti-windup, output limiter and output hysteresis

### Information

Block of a controller for set point tracking with a hysteresis element that switches the controller on and off.

If the controller is off, and the control error becomes larger than `eOn`, then the controller switches to on and remains on until the control error is smaller than `eOff`. When the controller is on, the set point tracking can be done using a P-, PI-, or PID-controller. In its off-mode, the control output is zero. Thus, the parameters `yMin` and `yMax` are used to constrain the output of the controller during its on mode only. This can be used, for example, to modulate a device between 0.3 and 1.0, and switch it to off when the control error is small enough.

Extends from Modelica.Blocks.Interfaces.SVcontrol (Single-Variable continuous controller).

### Parameters

Type | Name | Default | Description
--- | --- | --- | ---
Hysteresis
Real | eOn | 1 | if off and control error > eOn, switch to set point tracking
Real | eOff | -eOn | if on and control error < eOff, set y=0
Boolean | pre_y_start | false | Value of hysteresis output at initial time
Set point tracking
SimpleController | controllerType | Modelica.Blocks.Types.Simple... | Type of controller
Real | k | 1 | Gain of controller
Time | Ti |  | Time constant of Integrator block [s]
Time | Td |  | Time constant of Derivative block [s]
Real | yMax | 1 | Upper limit of output
Real | yMin | 0 | Lower limit of output
Real | wp | 1 | Set-point weight for Proportional block (0..1)
Real | wd | 0 | Set-point weight for Derivative block (0..1)
Real | Ni | 0.9 | Ni*Ti is time constant of anti-windup compensation
Real | Nd | 10 | The higher Nd, the more ideal the derivative block
Boolean | reverseAction | false | Set to true to enable reverse action (such as for a cooling coil controller)
Initialization
InitPID | initType | Modelica.Blocks.Types.InitPI... | Type of initialization (1: no init, 2: steady state, 3: initial state, 4: initial output)
Boolean | limitsAtInit | true | = false, if limits are ignored during initializiation
Real | xi_start | 0 | Initial or guess value value for integrator output (= integrator state)
Real | xd_start | 0 | Initial or guess value for state of derivative block
Real | y_start | 0 | Initial value of output

### Connectors

Type | Name | Description
--- | --- | ---
input RealInput | u_s | Connector of setpoint input signal
input RealInput | u_m | Connector of measurement input signal
output RealOutput | y | Connector of actuator output signal

### Modelica definition

model PIDHysteresis "PID controller with anti-windup, output limiter and output hysteresis" extends Modelica.Blocks.Interfaces.SVcontrol; parameter Real eOn = 1 "if off and control error > eOn, switch to set point tracking"; parameter Real eOff = -eOn "if on and control error < eOff, set y=0"; parameter Boolean pre_y_start=false "Value of hysteresis output at initial time"; parameter Modelica.Blocks.Types.SimpleController controllerType=Modelica.Blocks.Types.SimpleController.PID "Type of controller"; parameter Real k=1 "Gain of controller"; parameter Modelica.SIunits.Time Ti "Time constant of Integrator block"; parameter Modelica.SIunits.Time Td "Time constant of Derivative block"; parameter Real yMax=1 "Upper limit of output"; parameter Real yMin=0 "Lower limit of output"; parameter Real wp=1 "Set-point weight for Proportional block (0..1)"; parameter Real wd=0 "Set-point weight for Derivative block (0..1)"; parameter Real Ni=0.9 "Ni*Ti is time constant of anti-windup compensation"; parameter Real Nd=10 "The higher Nd, the more ideal the derivative block"; parameter Boolean reverseAction = false "Set to true to enable reverse action (such as for a cooling coil controller)"; parameter Modelica.Blocks.Types.InitPID initType=Modelica.Blocks.Types.InitPID.DoNotUse_InitialIntegratorState "Type of initialization (1: no init, 2: steady state, 3: initial state, 4: initial output)"; parameter Boolean limitsAtInit=true "= false, if limits are ignored during initializiation"; parameter Real xi_start=0 "Initial or guess value value for integrator output (= integrator state)"; parameter Real xd_start=0 "Initial or guess value for state of derivative block"; parameter Real y_start=0 "Initial value of output"; LimPID PID( controllerType=controllerType, k=k, Ti=Ti, yMax=yMax, yMin=yMin, wp=wp, wd=wd, Ni=Ni, Nd=Nd, initType=initType, limitsAtInit=limitsAtInit, xi_start=xi_start, xd_start=xd_start, y_start=y_start, Td=Td, reverseAction=reverseAction) "Controller for room temperature"; Modelica.Blocks.Logical.Hysteresis hys( pre_y_start=pre_y_start, uLow=eOff, uHigh=eOn) "Hysteresis element to switch controller on and off"; Modelica.Blocks.Logical.Switch swi; Modelica.Blocks.Sources.Constant zer(k=0) "Zero signal"; Modelica.Blocks.Math.Feedback feeBac; Modelica.Blocks.Logical.Switch swi1; equation assert(eOff < eOn, "Wrong controller parameters. Require eOff < eOn."); connect(zer.y, swi.u3); connect(swi.y, y); connect(u_m, PID.u_m); connect(hys.y, swi.u2); connect(PID.y, swi.u1); connect(u_s, feeBac.u1); connect(u_m, feeBac.u2); connect(feeBac.y, hys.u); connect(u_s, swi1.u1); connect(hys.y, swi1.u2); connect(u_m, swi1.u3); connect(swi1.y, PID.u_s); end PIDHysteresis;

## Buildings.Controls.Continuous.PIDHysteresisTimer

PID controller with anti-windup, hysteresis and timer to prevent short cycling

### Information

Block of a controller for set point tracking with a hysteresis element that switches the controller on and off, and a timer that prevents the controller to short cycle.

The controller is similar to Buildings.Controls.Continuous.PIDHysteresis but in addition, it has a timer that prevents the controller from switching to on too fast. When the controller switches off, the timer starts and avoids the controller from switching on until `minOffTime` seconds elapsed.

Extends from Modelica.Blocks.Interfaces.SVcontrol (Single-Variable continuous controller).

### Parameters

Type | Name | Default | Description
--- | --- | --- | ---
On/off controller
Real | minOffTime | 600 | Minimum time that devices needs to be off before it can run again
Real | eOn | 1 | if off and control error > eOn, switch to set point tracking
Real | eOff | -eOn | if on and control error < eOff, set y=0
Boolean | pre_y_start | false | Value of hysteresis output at initial time
Set point tracking
SimpleController | controllerType | Modelica.Blocks.Types.Simple... | Type of controller
Real | k | 1 | Gain of controller
Time | Ti |  | Time constant of Integrator block [s]
Time | Td |  | Time constant of Derivative block [s]
Real | yMax | 1 | Upper limit of modulating output
Real | yMin | 0.3 | Lower limit of modulating output (before switch to 0)
Real | wp | 1 | Set-point weight for Proportional block (0..1)
Real | wd | 0 | Set-point weight for Derivative block (0..1)
Real | Ni | 0.9 | Ni*Ti is time constant of anti-windup compensation
Real | Nd | 10 | The higher Nd, the more ideal the derivative block
Boolean | reverseAction | false | Set to true to enable reverse action (such as for a cooling coil controller)
Initialization
InitPID | initType | Modelica.Blocks.Types.InitPI... | Type of initialization (1: no init, 2: steady state, 3: initial state, 4: initial output)
Boolean | limitsAtInit | true | = false, if limits are ignored during initializiation
Real | xi_start | 0 | Initial or guess value value for integrator output (= integrator state)
Real | xd_start | 0 | Initial or guess value for state of derivative block
Real | y_start | 0 | Initial value of output

### Connectors

Type | Name | Description
--- | --- | ---
input RealInput | u_s | Connector of setpoint input signal
input RealInput | u_m | Connector of measurement input signal
output RealOutput | y | Connector of actuator output signal
output RealOutput | tOn | Time since boiler switched on
output RealOutput | tOff | Time since boiler switched off
output BooleanOutput | on | Outputs true if boiler is on

### Modelica definition

model PIDHysteresisTimer "PID controller with anti-windup, hysteresis and timer to prevent short cycling" extends Modelica.Blocks.Interfaces.SVcontrol; parameter Real minOffTime=600 "Minimum time that devices needs to be off before it can run again"; parameter Real eOn = 1 "if off and control error > eOn, switch to set point tracking"; parameter Real eOff = -eOn "if on and control error < eOff, set y=0"; parameter Boolean pre_y_start=false "Value of hysteresis output at initial time"; parameter Modelica.Blocks.Types.SimpleController controllerType=Modelica.Blocks.Types.SimpleController.PID "Type of controller"; parameter Real k=1 "Gain of controller"; parameter Modelica.SIunits.Time Ti "Time constant of Integrator block"; parameter Modelica.SIunits.Time Td "Time constant of Derivative block"; parameter Real yMax=1 "Upper limit of modulating output"; parameter Real yMin=0.3 "Lower limit of modulating output (before switch to 0)"; parameter Real wp=1 "Set-point weight for Proportional block (0..1)"; parameter Real wd=0 "Set-point weight for Derivative block (0..1)"; parameter Real Ni=0.9 "Ni*Ti is time constant of anti-windup compensation"; parameter Real Nd=10 "The higher Nd, the more ideal the derivative block"; parameter Boolean reverseAction = false "Set to true to enable reverse action (such as for a cooling coil controller)"; parameter Modelica.Blocks.Types.InitPID initType=Modelica.Blocks.Types.InitPID.DoNotUse_InitialIntegratorState "Type of initialization (1: no init, 2: steady state, 3: initial state, 4: initial output)"; parameter Boolean limitsAtInit=true "= false, if limits are ignored during initializiation"; parameter Real xi_start=0 "Initial or guess value value for integrator output (= integrator state)"; parameter Real xd_start=0 "Initial or guess value for state of derivative block"; parameter Real y_start=0 "Initial value of output"; Modelica.Blocks.Interfaces.RealOutput tOn "Time since boiler switched on"; Modelica.Blocks.Interfaces.RealOutput tOff "Time since boiler switched off"; LimPID con( controllerType=controllerType, k=k, Ti=Ti, Td=Td, wp=wp, wd=wd, Ni=Ni, Nd=Nd, initType=initType, limitsAtInit=limitsAtInit, xi_start=xi_start, xd_start=xd_start, y_start=y_start, final yMin=yMin, final yMax=yMax, reverseAction=reverseAction) "Controller to track setpoint"; protected Modelica.Blocks.Sources.Constant zer(k=0) "Zero signal"; Modelica.Blocks.Logical.Switch switch2; Modelica.Blocks.Logical.GreaterEqualThreshold greaterEqualThreshold(threshold= minOffTime); Modelica.Blocks.Logical.And and3; public OffTimer offHys; Modelica.Blocks.Logical.Timer onTimer; protected Modelica.Blocks.Logical.Not not1; public Modelica.Blocks.Logical.Timer offTimer; Modelica.Blocks.Interfaces.BooleanOutput on "Outputs true if boiler is on"; protected Modelica.Blocks.Logical.Switch switch1; public Modelica.Blocks.Math.Feedback feeBac; Modelica.Blocks.Logical.Hysteresis hys( pre_y_start=pre_y_start, uLow=eOff, uHigh=eOn) "Hysteresis element to switch controller on and off"; equation connect(u_m, con.u_m); connect(zer.y,switch2. u3); connect(switch2.y, y); connect(and3.y,switch2. u2); connect(greaterEqualThreshold.y, and3.u1); connect(offHys.y, greaterEqualThreshold.u); connect(con.y,switch2. u1); connect(onTimer.y, tOn); connect(offTimer.y, tOff); connect(and3.y, on); connect(and3.y, onTimer.u); connect(and3.y, not1.u); connect(not1.y, offTimer.u); connect(and3.y, switch1.u2); connect(u_s, switch1.u1); connect(u_m, switch1.u3); connect(switch1.y, con.u_s); connect(u_s, feeBac.u1); connect(u_m, feeBac.u2); connect(feeBac.y, hys.u); connect(hys.y, offHys.u); connect(hys.y, and3.u2); end PIDHysteresisTimer;

## Buildings.Controls.Continuous.SignalRanker

Ranks output signals such that y[i] >= y[i+1]

### Information

Block that sorts the input signal `u[:]` such that the output signal satisfies `y[i] >= y[i+1]` for all `i=1, ..., nin-1`.

This block may for example be used in a variable air volume flow controller to access the position of the dampers that are most open.

Extends from Modelica.Blocks.Interfaces.MIMO (Multiple Input Multiple Output continuous control block).

### Parameters

Type | Name | Default | Description
--- | --- | --- | ---
Integer | nin | 1 | Number of inputs
Integer | nout | nin | Number of outputs

### Connectors

Type | Name | Description
--- | --- | ---
input RealInput | u[nin] | Connector of Real input signals
output RealOutput | y[nout] | Connector of Real output signals

### Modelica definition

block SignalRanker "Ranks output signals such that y[i] >= y[i+1]" extends Modelica.Blocks.Interfaces.MIMO(final nout=nin); protected Real t "Temporary variable"; algorithm y[:] := u[:]; for i in 1:nin loop for j in 1:nin-1 loop if y[j] < y[j+1] then t := y[j+1]; y[j+1] := y[j]; y[j] := t; end if; end for; end for; end SignalRanker;