Enabled hysteresis in freeze stat (#2977)

For #2975
lbl-srg · Apr 27, 2022 · 2912509 · 2912509
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Showing 7 changed files with 120 additions and 104 deletions.
diff --git a/Buildings/Examples/VAVReheat/BaseClasses/FreezeStat.mo b/Buildings/Examples/VAVReheat/BaseClasses/FreezeStat.mo
@@ -30,7 +30,8 @@ model FreezeStat "Freeze thermostat with timed lockout"
     annotation (Placement(transformation(extent={{40,-10},{60,10}})));
   Buildings.Controls.OBC.CDL.Continuous.GreaterThreshold greThr(
     final t=TSet,
-    final h=0) "Greater comparison"
+    final h=0.5)
+    "Greater comparison"
     annotation (Placement(transformation(extent={{-60,-10},{-40,10}})));
 equation
   connect(locOut.y, freStaSig.u)
@@ -80,6 +81,12 @@ the set point.
 </html>", revisions="<html>
 <ul>
 <li>
+April 26, 2022, by Michael Wetter:<br/>
+Enabled hysteresis for freeze stat. This is required to avoid simulation to stall.<br/>
+This is for
+<a href=\"https://github.com/lbl-srg/modelica-buildings/issues/2975\">#2975</a>.
+</li>
+<li>
 April 23, 2021, by Michael Wetter:<br/>
 First implementation.
 </li>

diff --git a/Buildings/Resources/ReferenceResults/Dymola/Buildings_Examples_VAVReheat_ASHRAE2006.txt b/Buildings/Resources/ReferenceResults/Dymola/Buildings_Examples_VAVReheat_ASHRAE2006.txt
diff --git a/...ources/ReferenceResults/Dymola/Buildings_Examples_VAVReheat_Validation_TraceSubstance.txt b/...ources/ReferenceResults/Dymola/Buildings_Examples_VAVReheat_Validation_TraceSubstance.txt
diff --git a/...esults/Dymola/Buildings_ThermalZones_EnergyPlus_Examples_SmallOffice_ASHRAE2006Spring.txt b/...esults/Dymola/Buildings_ThermalZones_EnergyPlus_Examples_SmallOffice_ASHRAE2006Spring.txt
diff --git a/...esults/Dymola/Buildings_ThermalZones_EnergyPlus_Examples_SmallOffice_ASHRAE2006Summer.txt b/...esults/Dymola/Buildings_ThermalZones_EnergyPlus_Examples_SmallOffice_ASHRAE2006Summer.txt
diff --git a/...esults/Dymola/Buildings_ThermalZones_EnergyPlus_Examples_SmallOffice_ASHRAE2006Winter.txt b/...esults/Dymola/Buildings_ThermalZones_EnergyPlus_Examples_SmallOffice_ASHRAE2006Winter.txt
diff --git a/Buildings/package.mo b/Buildings/package.mo
@@ -245,6 +245,15 @@ have been <b style=\"color:blue\">improved</b> in a
 <b style=\"color:blue\">backward compatible</b> way:
 </p>
 <table class=\"releaseTable\" summary=\"summary\" border=\"1\" cellspacing=\"0\" cellpadding=\"2\" style=\"border-collapse:collapse;\">
+<tr><td colspan=\"2\"><b>Buildings.Examples.VAVReheat</b>
+    </td>
+</tr>
+<tr><td valign=\"top\">Buildings.Examples.VAVReheat.BaseClasses.Controls.FreezeStat
+  </td>
+  <td valign=\"top\">Added hysteresis. Without it, models can stall due to state events.<br/>
+                     This is for <a href=\"https://github.com/lbl-srg/modelica-buildings/issues/2975\">#2975</a>.
+  </td>
+</tr>
 <tr><td colspan=\"2\"><b>Buildings.Controls.OBC</b>
     </td>
 </tr>