Buildings.Controls.SetPoints

Information

Extends from Modelica.Icons.VariantsPackage (Icon for package containing variants).

Package Content

Name	Description
HotWaterTemperatureReset	Block to compute the supply and return set point of heating systems
OccupancySchedule	Occupancy schedule with look-ahead
Table	Model for a set point that is interpolated based on a user-specified table
Examples	Collection of models that illustrate model use and test models

Buildings.Controls.SetPoints.HotWaterTemperatureReset

Information

The parameter dTOutHeaBal can be used to shift the heating curve to take into account that heat gains from solar, equipment and people make up for some of the transmission losses. For example, in energy efficient houses, the heating may not be switched on if the outside air temperature is greater than 12°C, even if a room temperature of 20°C is required. In such a situation, set dTOutHeaBal=20-12=8 Kelvin to shift the heating curve.

Extends from Modelica.Blocks.Interfaces.BlockIcon (Basic graphical layout of input/output block).

Parameters

Type	Name	Default	Description
Real	m	1.3	Exponent for heat transfer
Boolean	use_TRoo_in	false	Get the room temperature set point from the input connector
Temperature	TRoo	293.15	Fixed value of room temperature set point [K]
TemperatureDifference	dTOutHeaBal	8	Offset for heating curve [K]
Nominal conditions
Temperature	TSup_nominal		Supply temperature [K]
Temperature	TRet_nominal		Return temperature [K]
Temperature	TRoo_nominal	293.15	Room temperature [K]
Temperature	TOut_nominal		Outside temperature [K]

Connectors

Type	Name	Description
input RealInput	TRoo_in	Room air temperature set point [K]
input RealInput	TOut	Outside temperature [K]
output RealOutput	TSup	Setpoint for supply temperature [K]
output RealOutput	TRet	Setpoint for return temperature [K]

Modelica definition

block HotWaterTemperatureReset 
  "Block to compute the supply and return set point of heating systems"
  extends Modelica.Blocks.Interfaces.BlockIcon;

  parameter Real m = 1.3 "Exponent for heat transfer";
  parameter Modelica.SIunits.Temperature TSup_nominal "Supply temperature";
  parameter Modelica.SIunits.Temperature TRet_nominal "Return temperature";
  parameter Modelica.SIunits.Temperature TRoo_nominal = 293.15 
    "Room temperature";
  parameter Modelica.SIunits.Temperature TOut_nominal "Outside temperature";

  parameter Boolean use_TRoo_in = false 
    "Get the room temperature set point from the input connector";
  parameter Modelica.SIunits.Temperature TRoo = 293.15 
    "Fixed value of room temperature set point";
  parameter Modelica.SIunits.TemperatureDifference dTOutHeaBal(displayUnit="K") = 8 
    "Offset for heating curve";
  Modelica.Blocks.Interfaces.RealInput TRoo_in(final quantity="Temperature",
                                               final unit = "K", displayUnit = "degC", min=0) if 
          use_TRoo_in "Room air temperature set point";

  Modelica.Blocks.Interfaces.RealInput TOut(final quantity="Temperature",
                                            final unit = "K", displayUnit = "degC", min=0) 
    "Outside temperature";
  Modelica.Blocks.Interfaces.RealOutput TSup(final quantity="Temperature",
                                            final unit = "K", displayUnit = "degC", min=0) 
    "Setpoint for supply temperature";
  Modelica.Blocks.Interfaces.RealOutput TRet(final quantity="Temperature",
                                            final unit = "K", displayUnit = "degC", min=0) 
    "Setpoint for return temperature";

protected 
  Modelica.Blocks.Interfaces.RealInput TRoo_in_internal(final quantity="Temperature",
                                                        final unit = "K", displayUnit = "degC", min=0) 
    "Needed to connect to conditional connector";
  Real qRel "Relative heating load = Q_flow/Q_flow_nominal";
  Modelica.SIunits.Temperature TOutOffSet 
    "Effective outside temperature for heat transfer (takes into account room heat gains)";
  parameter Modelica.SIunits.Temperature TOutOffSet_nominal =  TOut_nominal + dTOutHeaBal 
    "Effective outside temperature for heat transfer at nominal conditions (takes into account room heat gains)";

equation 
  connect(TRoo_in, TRoo_in_internal);
  if not use_TRoo_in then
    TRoo_in_internal = TRoo;
  end if;
 TOutOffSet = TOut + dTOutHeaBal;
 // Relative heating load, compared to nominal conditions
 qRel = max(0, (TRoo_in_internal-TOutOffSet)/(TRoo_nominal-TOutOffSet_nominal));
 TSup = TRoo_in_internal
          + ((TSup_nominal+TRet_nominal)/2-TRoo_in_internal) * qRel^(1/m)
          + (TSup_nominal-TRet_nominal)/2 * qRel;
 TRet = TSup - qRel * (TSup_nominal-TRet_nominal);
end HotWaterTemperatureReset;

Buildings.Controls.SetPoints.OccupancySchedule

Information

This model outputs whether the building is currently occupied, and how long it will take until the next time when the building will be occupied or non-occupied. The latter may be used, for example, to start a ventilation system half an hour before occupancy starts in order to ventilate the room.

The occupancy is defined by a time schedule of the form

  occupancy = 3600*{7, 12, 14, 19}

Extends from Modelica.Blocks.Interfaces.BlockIcon (Basic graphical layout of input/output block).

Parameters

Type	Name	Default	Description
Real	occupancy[:]	3600*{7,19}	Occupancy table, each entry switching occupancy on or off
Boolean	firstEntryOccupied	true	Set to true if first entry in occupancy denotes a changed from unoccupied to occupied
Time	period	86400	End time of periodicity [s]

Connectors

Type	Name	Description
output RealOutput	tNexNonOcc	Time until next non-occupancy
output RealOutput	tNexOcc	Time until next occupancy
output BooleanOutput	occupied	Outputs true if occupied at current time

Modelica definition

block OccupancySchedule "Occupancy schedule with look-ahead"
  extends Modelica.Blocks.Interfaces.BlockIcon;

  parameter Real occupancy[:]=3600*{7, 19} 
    "Occupancy table, each entry switching occupancy on or off";
  parameter Boolean firstEntryOccupied = true 
    "Set to true if first entry in occupancy denotes a changed from unoccupied to occupied";
  parameter Modelica.SIunits.Time period =   86400 "End time of periodicity";

  Modelica.Blocks.Interfaces.RealOutput tNexNonOcc 
    "Time until next non-occupancy";
  Modelica.Blocks.Interfaces.RealOutput tNexOcc "Time until next occupancy";
  Modelica.Blocks.Interfaces.BooleanOutput occupied 
    "Outputs true if occupied at current time";

protected 
  final parameter Integer nRow = size(occupancy,1) 
    "Number of rows in the schedule";

  output Modelica.SIunits.Time offSet=integer(time/period)*period 
    "Time off-set, in multiples of period, that is used to switch the time when doing the table lookup";
  output Integer nexStaInd "Next index when occupancy starts";
  output Integer nexStoInd "Next index when occupancy stops";

  output Integer iPerSta 
    "Counter for the period in which the next occupancy starts";
  output Integer iPerSto 
    "Counter for the period in which the next occupancy stops";

  output Modelica.SIunits.Time tOcc "Time when next occupancy starts";
  output Modelica.SIunits.Time tNonOcc "Time when next non-occupancy starts";

encapsulated function switchInteger
  input Integer x1;
  input Integer x2;
  output Integer y1;
  output Integer y2;
algorithm 
  y1:=x2;
  y2:=x1;
end switchInteger;

encapsulated function switchReal
  input Real x1;
  input Real x2;
  output Real y1;
  output Real y2;
algorithm 
  y1:=x2;
  y2:=x1;
end switchReal;

initial algorithm 
  // Check parameters for correctness
 assert(mod(nRow, 2) < 0.1,
   "The parameter \"occupancy\" must have an even number of elements.\n");
 assert(0 < occupancy[1],
   "The first element of \"occupancy\" must be bigger than zero."
   + "\n   Received occupancy[1] = " + String(occupancy[1]));
 assert(period > occupancy[nRow],
   "The parameter \"period\" must be greater than the last element of \"occupancy\"."
   + "\n   Received period      = " + String(period)
   + "\n            occupancy[" + String(nRow) +
     "] = " + String(occupancy[nRow]));
  for i in 1:nRow-1 loop
    assert(occupancy[i] < occupancy[i+1],
      "The elements of the parameter \"occupancy\" must be strictly increasing.");
  end for;

 // Initialize variables
 iPerSta   := integer(time/period);
 iPerSto   := iPerSta;

 // First, assume that the first entry is occupied
 nexStaInd := 1;
 nexStoInd := 2;
 // nRow is an even number
 for i in 1:2:nRow-1 loop
   if time >= occupancy[i] + iPerSta*period then
     nexStaInd := i+2;
   end if;
 end for;
 for i in 2:2:nRow loop
   if time >= occupancy[i] + iPerSto*period then
     nexStoInd := i+2;
   end if;
 end for;
 if nexStaInd > nRow then
    nexStaInd := 1;
    iPerSta :=iPerSta + 1;
 end if;
 if nexStoInd > nRow then
    nexStoInd := 2;
    iPerSto :=iPerSto + 1;
 end if;
 tOcc    := occupancy[nexStaInd]+iPerSta*period;
 tNonOcc := occupancy[nexStoInd]+iPerSto*period;
 occupied := tNonOcc < tOcc;

 // Now, correct if the first entry is vaccant instead of occupied
 if not firstEntryOccupied then
   (nexStaInd, nexStoInd) := switchInteger(nexStaInd, nexStoInd);
   (iPerSta, iPerSto)     := switchInteger(iPerSta,   iPerSto);
   (tOcc, tNonOcc)        := switchReal(tOcc,      tNonOcc);
   occupied := not occupied;
 end if;

algorithm 
  when time >= pre(tOcc) then
    nexStaInd :=nexStaInd + 2;
    occupied := not occupied;
    // Wrap index around
    if nexStaInd > nRow then
       nexStaInd := if firstEntryOccupied then 1 else 2;
       iPerSta :=iPerSta + 1;
    end if;
    tOcc := occupancy[nexStaInd] + iPerSta*period;
  end when;

  // Changed the index that computes the time until the next non-occupancy
  when time >= pre(tNonOcc) then
    nexStoInd :=nexStoInd + 2;
    occupied := not occupied;
    // Wrap index around
    if nexStoInd > nRow then
       nexStoInd := if firstEntryOccupied then 2 else 1;
       iPerSto :=iPerSto + 1;
    end if;
    tNonOcc := occupancy[nexStoInd] + iPerSto*period;
  end when;

 tNexOcc    := tOcc-time;
 tNexNonOcc := tNonOcc-time;
 assert(tNexOcc > -1e-3 and tNexOcc < period+1E-3, "tNexOcc must be non-zero and smaller than period.
   Received tNexOcc = " + String(tNexOcc));
 assert(tNexNonOcc > -1e-3 and tNexOcc < period+1E-3, "tNexNonOcc must be non-zero and smaller than period.
   Received tNexNonOcc = " + String(tNexNonOcc));

end OccupancySchedule;

Buildings.Controls.SetPoints.Table

Information

Buildings.Controls.SetPoints.Table tabLinExt(constantExtrapolation=false, 
                                             table=[20, 0.0; 
                                                    22, 0.5; 
                                                    25, 0.5; 
                                                    26, 1.0]);
Buildings.Controls.SetPoints.Table tabConExt(constantExtrapolation=true, 
                                             table=[20, 0.0; 
                                                    22, 0.5; 
                                                    25, 0.5; 
                                                    26, 1.0]);

For the default setting constantExtrapolation=true, the block outputs y=y1+offset for u ≤ u1, and y=yMax+offset for u ≥ uMax. Otherwise, the table is linearly extrapolated with a constant derivative.

Note that the first column must be strictly increasing.

Extends from Modelica.Blocks.Interfaces.SISO (Single Input Single Output continuous control block).

Parameters

Type	Name	Default	Description
Real	table[:, 2]	fill(0.0, 1, 2)	Table matrix ( e.g., table=[u1, y1; u2, y2; u3, y3])
Real	offset	0	Offset of output signal
Boolean	constantExtrapolation	true	If true, then y=y1 for u<u1, and y=yMax for u>uMax

Connectors

Type	Name	Description
input RealInput	u	Connector of Real input signal
output RealOutput	y	Connector of Real output signal

Modelica definition

model Table 
  "Model for a set point that is interpolated based on a user-specified table"
  extends Modelica.Blocks.Interfaces.SISO;
  parameter Real table[:,2]=fill(0.0, 1, 2) 
    "Table matrix ( e.g., table=[u1, y1; u2, y2; u3, y3])";

  parameter Real offset=0 "Offset of output signal";

  parameter Boolean constantExtrapolation = true 
    "If true, then y=y1 for u<u1, and y=yMax for u>uMax";

protected 
  final parameter Integer nCol = if constantExtrapolation then 
                        size(table,1)+2 else 
                        size(table,1) "Number of columns";
  final parameter Real[nCol,2] offsetVector = [zeros(nCol), offset*ones(nCol)] 
    "Vector to take offset of output signal into account";
  Modelica.Blocks.Tables.CombiTable1D tab(
    tableOnFile=false,
    final table= (if constantExtrapolation then 
                    cat(1, [table[1,1]-1, table[1,2]],
                           table,
                           [table[end,1]+1, table[end,2]]) else 
                    table)
                  +offsetVector) "Table used for interpolation";
equation 
  connect(u, tab.u[1]);

  connect(tab.y[1], y);

end Table;