Made model C1 for #373

lbl-srg · Mar 12, 2015 · a5798bc · a5798bc
1 parent e405042
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Showing 5 changed files with 58 additions and 19 deletions.
diff --git a/Buildings/Fluid/Chillers/BaseClasses/PartialElectric.mo b/Buildings/Fluid/Chillers/BaseClasses/PartialElectric.mo
@@ -27,7 +27,7 @@ partial model PartialElectric
   Modelica.SIunits.Temperature TConEnt "Condenser entering temperature";
   Modelica.SIunits.Temperature TConLvg "Condenser leaving temperature";
 
-  Real COP(min=0) "Coefficient of performance";
+  Real COP(min=0, unit="1") "Coefficient of performance";
   Modelica.SIunits.HeatFlowRate QCon_flow "Condenser heat input";
   Modelica.SIunits.HeatFlowRate QEva_flow "Evaporator heat input";
   Modelica.Blocks.Interfaces.RealOutput P(final quantity="Power", unit="W")
@@ -90,6 +90,7 @@ protected
 
 initial equation
   assert(QEva_flow_nominal < 0, "Parameter QEva_flow_nominal must be smaller than zero.");
+  assert(Q_flow_small < 0, "Parameter Q_flow_small must be smaller than zero.");
   assert(PLRMinUnl >= PLRMin, "Parameter PLRMinUnl must be bigger or equal to PLRMin");
   assert(PLRMax > PLRMinUnl, "Parameter PLRMax must be bigger than PLRMinUnl");
 equation
@@ -111,22 +112,42 @@ equation
     // Available cooling capacity
     QEva_flow_ava = QEva_flow_nominal*capFunT;
     // Cooling capacity required to chill water to setpoint
-    QEva_flow_set = min(m2_flow*(hSet-inStream(port_a2.h_outflow)),0);
+    QEva_flow_set = Buildings.Utilities.Math.Functions.smoothMin(
+      x1=  m2_flow*(hSet-inStream(port_a2.h_outflow)),
+      x2= Q_flow_small,
+      deltaX=-Q_flow_small/100);
 
     // Part load ratio
-    PLR1 = min(QEva_flow_set/(QEva_flow_ava+Q_flow_small), PLRMax);
+    PLR1 = Buildings.Utilities.Math.Functions.smoothMin(
+      x1=  QEva_flow_set/(QEva_flow_ava+Q_flow_small),
+      x2=  PLRMax,
+      deltaX=PLRMax/100);
     // PLR2 is the compressor part load ratio. The lower bound PLRMinUnl is
     // since for PLR1<PLRMinUnl, the chiller uses hot gas bypass, under which
     // condition the compressor power is assumed to be the same as if the chiller
     // were to operate at PLRMinUnl
-    PLR2 = max(PLRMinUnl, PLR1);
-    // Cycling ratio
-    CR = min(PLR1/PLRMin,1.0);
+    PLR2 = Buildings.Utilities.Math.Functions.smoothMax(
+      x1=  PLRMinUnl,
+      x2=  PLR1,
+      deltaX=  PLRMinUnl/100);
+
+    // Cycling ratio.
+    // Due to smoothing, this can be about deltaX/10 above 1.0
+    CR = Buildings.Utilities.Math.Functions.smoothMin(
+      x1=  PLR1/PLRMin,
+      x2=  1,
+      deltaX=0.001);
 
     // Compressor power.
     P = -QEva_flow_ava/COP_nominal*EIRFunT*EIRFunPLR*CR;
     // Heat flow rates into evaporator and condenser
-    QEva_flow = max(QEva_flow_set, QEva_flow_ava);
+    // Q_flow_small is a negative number.
+    QEva_flow = Buildings.Utilities.Math.Functions.smoothMax(
+      x1=  QEva_flow_set,
+      x2=  QEva_flow_ava,
+      deltaX= -Q_flow_small/10);
+
+  //QEva_flow = max(QEva_flow_set, QEva_flow_ava);
     QCon_flow = -QEva_flow + P*etaMotor;
     // Coefficient of performance
     COP = -QEva_flow/(P-Q_flow_small);
@@ -308,6 +329,11 @@ The function value needs to be assigned to <code>EIRFunPLR</code>.
 revisions="<html>
 <ul>
 <li>
+March 12, 2015, by Michael Wetter:<br/>
+Refactored model to make it once continuously differentiable.
+This is for issue <a href=\"https://github.com/lbl-srg/modelica-buildings/issues/373\">373</a>.
+</li>
+<li>
 Jan. 10, 2011, by Michael Wetter:<br/>
 Added input signal to switch chiller off, and changed base class to use a dynamic model.
 The change of the base class was required to improve the robustness of the model when the control

diff --git a/Buildings/Fluid/Chillers/Carnot.mo b/Buildings/Fluid/Chillers/Carnot.mo
@@ -2,8 +2,7 @@ within Buildings.Fluid.Chillers;
 model Carnot
   "Chiller with performance curve adjusted based on Carnot efficiency"
  extends Interfaces.FourPortHeatMassExchanger(
-    vol1(
-      final prescribedHeatFlowRate = true),
+    vol1(final prescribedHeatFlowRate = true),
     redeclare final Buildings.Fluid.MixingVolumes.MixingVolume vol2);
 
   parameter Buildings.Fluid.Types.EfficiencyInput effInpEva=

diff --git a/Buildings/Fluid/Chillers/ElectricEIR.mo b/Buildings/Fluid/Chillers/ElectricEIR.mo
@@ -39,8 +39,10 @@ equation
     // Since the regression for capacity can have negative values (for unreasonable temperatures),
     // we constrain its return value to be non-negative. This prevents the solver to pick the
     // unrealistic solution.
-    capFunT = max(0,
-       Buildings.Utilities.Math.Functions.biquadratic(a=per.capFunT, x1=TEvaLvg_degC, x2=TConEnt_degC));
+    capFunT = Buildings.Utilities.Math.Functions.smoothMax(
+       x1=  1E-6,
+       x2=  Buildings.Utilities.Math.Functions.biquadratic(a=per.capFunT, x1=TEvaLvg_degC, x2=TConEnt_degC),
+       deltaX=  1E-7);
 /*    assert(capFunT > 0.1, "Error: Received capFunT = " + String(capFunT)  + ".\n"
            + "Coefficient for polynomial seem to be not valid for the encountered temperature range.\n"
            + "Temperatures are TConEnt_degC = " + String(TConEnt_degC) + " degC\n"
@@ -220,6 +222,11 @@ Component Models. <i>ASHRAE Transactions</i>, AC-02-9-1.
 revisions="<html>
 <ul>
 <li>
+March 12, 2015, by Michael Wetter:<br/>
+Refactored model to make it once continuously differentiable.
+This is for issue <a href=\"https://github.com/lbl-srg/modelica-buildings/issues/373\">373</a>.
+</li>
+<li>
 Jan. 9, 2011, by Michael Wetter:<br/>
 Added input signal to switch chiller off.
 </li>

diff --git a/Buildings/Fluid/Chillers/ElectricReformulatedEIR.mo b/Buildings/Fluid/Chillers/ElectricReformulatedEIR.mo
@@ -40,8 +40,10 @@ equation
     // Since the regression for capacity can have negative values (for unreasonable temperatures),
     // we constrain its return value to be non-negative. This prevents the solver to pick the
     // unrealistic solution.
-    capFunT = max(0,
-       Buildings.Utilities.Math.Functions.biquadratic(a=per.capFunT, x1=TEvaLvg_degC, x2=TConLvg_degC));
+    capFunT = Buildings.Utilities.Math.Functions.smoothMax(
+      x1=  1E-6,
+      x2=  Buildings.Utilities.Math.Functions.biquadratic(a=per.capFunT, x1=TEvaLvg_degC, x2=TConLvg_degC),
+      deltaX=  1E-7);
 /*    assert(capFunT > 0.1, "Error: Received capFunT = " + String(capFunT)  + ".\n"
            + "Coefficient for polynomial seem to be not valid for the encountered temperature range.\n"
            + "Temperatures are TConLvg_degC = " + String(TConLvg_degC) + " degC\n"
@@ -217,6 +219,11 @@ Component Models. <i>ASHRAE Transactions</i>, AC-02-9-1.
 revisions="<html>
 <ul>
 <li>
+March 12, 2015, by Michael Wetter:<br/>
+Refactored model to make it once continuously differentiable.
+This is for issue <a href=\"https://github.com/lbl-srg/modelica-buildings/issues/373\">373</a>.
+</li>
+<li>
 Jan. 9, 2011, by Michael Wetter:<br/>
 Added input signal to switch chiller off.
 </li>