Buildings.Controls.OBC.Utilities.PIDWithAutotuning.Relay
Package with blocks for a relay controller
Information
This package contains blocks related to a relay controller.
Package Content
| Name | Description |
|---|---|
 Controller
|
Output relay signals for tuning PID controllers |
 ResponseProcess
|
Calculate the lengths of the on and off period, the half period ratio, and the times when the tuning starts and ends |
 Validation
|
Collection of models that validate the blocks of a relay controller |
 BaseClasses
|
Package with base classes |
Buildings.Controls.OBC.Utilities.PIDWithAutotuning.Relay.Controller
Output relay signals for tuning PID controllers
Information
This block generates a relay output yDif = (u_m - u_s)/r, where
u_m is the measurement,
u_s is the setpoint and
r is the typical range of control error.
This block also generates the control output y,
and a boolean relay switch output yOn using the following
procedure.
Step 1: Calculate control error,
-
If the parameter
reverseActing = true, set the control errorerr = (u_s - u_m)/r, else seterr = (u_m - u_s)/r.
Step 2: Calculate y and yOn,
-
If
err > deaBanandtrigger = true, theny = yHigandyOn = true, -
else if
err < -deaBanandtrigger = true, theny = yLowandyOn = false, -
else,
yandyOnare kept as the initial values.
where deaBan is a dead band, yHig and yLow
are the higher value and the lower value of the output y, respectively.
References
J. Berner (2017). "Automatic Controller Tuning using Relay-based Model Identification." Department of Automatic Control, Lund University.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Real | r | 1 | Typical range of control error, used for scaling the control error |
| Real | yHig | Higher value for the relay output | |
| Real | yLow | Lower value for the relay output | |
| Real | deaBan | Deadband for holding the relay output | |
| Boolean | reverseActing | true | Set to true for reverse acting, or false for direct acting control action |
Connectors
| Type | Name | Description |
|---|---|---|
| input RealInput | u_s | Setpoint input signal |
| input RealInput | u_m | Measurement input signal |
| input BooleanInput | trigger | Connector for enabling the relay controller |
| output RealOutput | y | Control output |
| output BooleanOutput | yOn | Relay switch output, true when control output switches to the higher value |
| output RealOutput | yDif | Input difference, measurement - setpoint |
Modelica definition
block Controller
"Output relay signals for tuning PID controllers"
parameter Real r(min=100*Buildings.Controls.OBC.CDL.Constants.eps) = 1
"Typical range of control error, used for scaling the control error";
parameter Real yHig(
final min=1E-6)
"Higher value for the relay output";
parameter Real yLow(
final min=1E-6,
final max=yHig)
"Lower value for the relay output";
parameter Real deaBan(min=1E-6)
"Deadband for holding the relay output";
parameter Boolean reverseActing=true
"Set to true for reverse acting, or false for direct acting control action";
Buildings.Controls.OBC.CDL.Interfaces.RealInput u_s
"Setpoint input signal";
Buildings.Controls.OBC.CDL.Interfaces.RealInput u_m
"Measurement input signal";
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput trigger
"Connector for enabling the relay controller";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput y
"Control output";
Buildings.Controls.OBC.CDL.Interfaces.BooleanOutput yOn
"Relay switch output, true when control output switches to the higher value";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput yDif
"Input difference, measurement - setpoint";
protected
Buildings.Controls.OBC.CDL.Reals.Switch swi
"Switch between a higher value and a lower value";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant higVal(
final k=yHig)
"Higher value for the output";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant lowVal(
final k=yLow)
"Lower value for the output";
Buildings.Controls.OBC.CDL.Reals.Switch swi1
"Switch between a higher value and a lower value";
Buildings.Controls.OBC.CDL.Reals.Subtract revActErr if reverseActing
"Control error when reverse acting, setpoint - measurement";
Buildings.Controls.OBC.CDL.Reals.Hysteresis hys(
final uLow=-deaBan,
final uHigh=deaBan,
final pre_y_start=true)
"Check if the input difference exceeds the thresholds, by default the relay control is on";
Buildings.Controls.OBC.CDL.Reals.Subtract dirActErr if not reverseActing
"Control error when direct acting, measurement - setpoint";
Buildings.Controls.OBC.CDL.Reals.Subtract meaSetDif
"Inputs difference, (measurement - setpoint)";
Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter gaiYDif(
final k=1/r)
"Gain to normalized control error by r";
Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter gaiRevActErr(
final k=1/r) if reverseActing
"Gain to normalized control error by r";
Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter gaiDirActErr(
final k=1/r) if not reverseActing
"Gain to normalized control error by r";
equation
connect(swi.y, y);
connect(higVal.y, swi.u1);
connect(lowVal.y, swi.u3);
connect(swi1.u3, u_s);
connect(trigger, swi1.u2);
connect(u_m, swi1.u1);
connect(u_s, revActErr.u1);
connect(u_s, dirActErr.u2);
connect(swi1.y, revActErr.u2);
connect(swi1.y, dirActErr.u1);
connect(hys.y, swi.u2);
connect(hys.y, yOn);
connect(swi1.y, meaSetDif.u1);
connect(u_s, meaSetDif.u2);
connect(meaSetDif.y, gaiYDif.u);
connect(gaiYDif.y, yDif);
connect(revActErr.y, gaiRevActErr.u);
connect(gaiRevActErr.y, hys.u);
connect(dirActErr.y, gaiDirActErr.u);
connect(gaiDirActErr.y, hys.u);
end Controller;
Buildings.Controls.OBC.Utilities.PIDWithAutotuning.Relay.ResponseProcess
Calculate the lengths of the on and off period, the half period ratio, and the times when the tuning starts and ends
Information
This block processes a relay switch output signal and calculates
- the length of the on period,
- the length of the off period,
- the normalized time delay of the responses, and
- the flags which indicate if the tuning starts and completes.
For more details, please refer to:
- Buildings.Controls.OBC.Utilities.PIDWithAutotuning.Relay.BaseClasses.HalfPeriodRatio,
- Buildings.Controls.OBC.Utilities.PIDWithAutotuning.Relay.BaseClasses.NormalizedTimeDelay,
- Buildings.Controls.OBC.Utilities.PIDWithAutotuning.Relay.BaseClasses.OnOffPeriod.
- Buildings.Controls.OBC.Utilities.PIDWithAutotuning.Relay.BaseClasses.TuningMonitor.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Real | yHig | Higher value for the output | |
| Real | yLow | Lower value for the output |
Connectors
| Type | Name | Description |
|---|---|---|
| input BooleanInput | on | Relay switch. True: tuning on perid, False: tuning off period |
| input RealInput | tim | Simulation time [s] |
| input BooleanInput | trigger | Reset the output when trigger becomes true |
| input BooleanInput | inTun | Check if a tuning is ongoing |
| output RealOutput | tOn | Length of the on period [s] |
| output RealOutput | tOff | Length of the off period [s] |
| output BooleanOutput | triSta | True: the tuning starts |
| output BooleanOutput | triEnd | True: the tuning ends |
| output RealOutput | tau | Normalized time delay |
Modelica definition
block ResponseProcess
"Calculate the lengths of the on and off period, the half period ratio, and the times when the tuning starts and ends"
parameter Real yHig(min=1E-6)
"Higher value for the output";
parameter Real yLow(min=1E-6)
"Lower value for the output";
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput on
"Relay switch. True: tuning on perid, False: tuning off period";
Buildings.Controls.OBC.CDL.Interfaces.RealInput tim(
final quantity="Time",
final unit="s")
"Simulation time";
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput trigger
"Reset the output when trigger becomes true";
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput inTun
"Check if a tuning is ongoing";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput tOn(
final quantity="Time",
final unit="s",
min=100*Buildings.Controls.OBC.CDL.Constants.eps)
"Length of the on period";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput tOff(
final quantity="Time",
final unit="s",
min=100*Buildings.Controls.OBC.CDL.Constants.eps)
"Length of the off period";
Buildings.Controls.OBC.CDL.Interfaces.BooleanOutput triSta
"True: the tuning starts";
Buildings.Controls.OBC.CDL.Interfaces.BooleanOutput triEnd
"True: the tuning ends";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput tau
"Normalized time delay";
protected
Buildings.Controls.OBC.Utilities.PIDWithAutotuning.Relay.BaseClasses.OnOffPeriod
onOffPer
"Block that calculates the length of the on period and the off period";
Buildings.Controls.OBC.Utilities.PIDWithAutotuning.Relay.BaseClasses.HalfPeriodRatio
halPerRatio
"Block that calculates the half period ratio";
Buildings.Controls.OBC.Utilities.PIDWithAutotuning.Relay.BaseClasses.NormalizedTimeDelay
norTimDel(
final gamma=max(yHig, yLow)/min(yLow, yHig))
"Block that calculates the normalized time delay";
Buildings.Controls.OBC.Utilities.PIDWithAutotuning.Relay.BaseClasses.TuningMonitor
tunMon "Block that detects when the tuning period starts and ends";
equation
connect(onOffPer.on,on);
connect(onOffPer.tim, tim);
connect(onOffPer.tOn, halPerRatio.tOn);
connect(onOffPer.tOff, halPerRatio.tOff);
connect(halPerRatio.rho, norTimDel.rho);
connect(tOn, halPerRatio.tOn);
connect(tOff, halPerRatio.tOff);
connect(norTimDel.tau, tau);
connect(tunMon.triSta, triSta);
connect(tunMon.triEnd, triEnd);
connect(tunMon.tOn, onOffPer.tOn);
connect(tunMon.tOff, onOffPer.tOff);
connect(halPerRatio.TunEnd, tunMon.triEnd);
connect(onOffPer.trigger, trigger);
connect(norTimDel.inTun, inTun);
end ResponseProcess;