Implement with use of overconstrained connector

dietmarw · dietmarw · commit 1424c678f8c6 · 2026-04-10T16:55:43.000+02:00
The previous variant did not allow for parallel connections.
diff --git a/OpenHPL/ElectroMech/BaseClasses/BaseValve.mo b/OpenHPL/ElectroMech/BaseClasses/BaseValve.mo
@@ -34,7 +34,7 @@ equation
   Vdot = mdot/data.rho;
   dp*(C_v_*max(epsilon, u^alpha))^2 = Vdot*abs(Vdot) "Valve equation for pressure drop";
   dp = i.p - o.p "Link the pressure drop to the ports";
-  o.z = i.z "Elevation propagation: no height change across valve";
+  o.elevation.z = i.elevation.z "Elevation propagation: no height change across valve";
   annotation (preferredView="info", Documentation(info="<html>
 <p>
 This is a partial, simple model of hydraulic valve. &nbsp;</p><p>This model is based on the energy balance of a valve.
diff --git a/OpenHPL/ElectroMech/Turbines/Francis.mo b/OpenHPL/ElectroMech/Turbines/Francis.mo
@@ -210,7 +210,7 @@ equation
     p_tr2 = o.p;
     i.mdot+o.mdot=0;
     mdot=i.mdot;
-    o.z = i.z "Elevation propagation: no height change across turbine";
+    o.elevation.z = i.elevation.z "Elevation propagation: no height change across turbine";
 
   connect(p_out, P_out) annotation (Line(points={{40,90},{40,110}}, color={0,0,127}));
     annotation (preferredView="info",
diff --git a/OpenHPL/ElectroMech/Turbines/Pelton.mo b/OpenHPL/ElectroMech/Turbines/Pelton.mo
@@ -54,7 +54,7 @@ equation
   // Flow rate connectors
     i.mdot+o.mdot=0;
     mdot=i.mdot;
-    o.z = i.z "Elevation propagation: no height change across turbine";
+    o.elevation.z = i.elevation.z "Elevation propagation: no height change across turbine";
 
   connect(p_out, P_out) annotation (Line(points={{40,90},{40,110}}, color={0,0,127}));
     annotation (preferredView="info",
diff --git a/OpenHPL/Interfaces/Contact.mo b/OpenHPL/Interfaces/Contact.mo
@@ -4,9 +4,8 @@ connector Contact "Water flow connector"
   SI.Pressure p "Contact pressure";
   //SI.Temperature T "Contact temperature";
   flow SI.MassFlowRate mdot "Mass flow rate through the contact";
-  SI.Height z "Elevation at connection point";
-  flow Real gz(unit="m2/s") "Auxiliary elevation flow variable (always zero, for connector balance)";
- 
+  Elevation elevation "Overconstrained elevation at connection point";
+
   annotation (
     Documentation(info = "<html>
 <p>Contact is a basic water flow connector, which consists of water pressure, mass flow rate,
@@ -16,15 +15,17 @@ and elevation at the connector (positive if water is flowing into connector and
 <ul>
 <li><code>p</code> &ndash; Pressure (potential variable, equated across connections)</li>
 <li><code>mdot</code> &ndash; Mass flow rate (flow variable, summed to zero across connections)</li>
-<li><code>z</code> &ndash; Elevation (potential variable, equated across connections).
+<li><code>elevation.z</code> &ndash; Elevation (overconstrained variable, propagated via spanning tree).
 Each component provides an equation relating its connector elevations,
 enabling automatic propagation of absolute elevation through the system.
-Source components (e.g., Reservoir) set the absolute reference elevation.</li>
+Source components (e.g., Reservoir) set the absolute reference elevation.
+Uses the overconstrained connector mechanism (Modelica Spec 9.4) to support
+arbitrary topologies including parallel pipes and loops.</li>
 </ul>
 </html>"),
   Icon(graphics = {
-    Text(origin = {0, -175}, 
-         textColor = {0, 85, 255}, 
-         extent = {{-100, 100}, {100, -100}}, 
-         textString = DynamicSelect("", if showElevation then String(z) else ""))}));
+    Text(origin = {0, -175},
+         textColor = {0, 85, 255},
+         extent = {{-100, 100}, {100, -100}},
+         textString = DynamicSelect("", if showElevation then String(elevation.z) else ""))}));
 end Contact;
diff --git a/OpenHPL/Interfaces/Elevation.mo b/OpenHPL/Interfaces/Elevation.mo
@@ -0,0 +1,10 @@
+within OpenHPL.Interfaces;
+record Elevation "Overconstrained elevation record for connector balance"
+  SI.Position z "Elevation at connection point";
+  function equalityConstraint
+    input Elevation e1;
+    input Elevation e2;
+    output Real residue[0] "No residual equations — elevation is propagated via spanning tree";
+  algorithm
+  end equalityConstraint;
+end Elevation;
diff --git a/OpenHPL/Interfaces/TwoContacts.mo b/OpenHPL/Interfaces/TwoContacts.mo
@@ -8,7 +8,7 @@ partial model TwoContacts "Model of two connectors"
                                annotation (
     Placement(transformation(extent={{90,-10},{110,10}})));
 equation
-  o.gz = i.gz "Elevation auxiliary variable: propagate gz from inlet to outlet";
+  Connections.branch(i.elevation, o.elevation) "Elevation graph: inlet and outlet are in the same connected set";
   annotation (
     Documentation(info = "<html>
     <p>TwoContact is a partial model, which consists of two Contacts <em>i</em>and <em>o</em>.
diff --git a/OpenHPL/Interfaces/package.order b/OpenHPL/Interfaces/package.order
@@ -1,5 +1,6 @@
 Contact
 Contact_i
 Contact_o
+Elevation
 TurbineContacts
 TwoContacts
diff --git a/OpenHPL/Waterway/BendPipe.mo b/OpenHPL/Waterway/BendPipe.mo
@@ -23,7 +23,7 @@ equation
   o.p = i.p - dp "Pressure of the output connector";
   i.mdot + o.mdot = 0 "Mass balance";
   mdot = i.mdot "Flow direction";
-  o.z = i.z "Elevation propagation: no height change across bend";
+  o.elevation.z = i.elevation.z "Elevation propagation: no height change across bend";
   annotation (preferredView="info",
     Documentation(info="<html>
 <p>Usually minor head losses in pipes are considered to be due to fittings, diffusers, nozzles, bend in pipes, etc. We are more interested in head loss due to bend pipes for this model.</p>
diff --git a/OpenHPL/Waterway/DraftTube.mo b/OpenHPL/Waterway/DraftTube.mo
@@ -153,7 +153,7 @@ equation
   p_o = o.p;
   i.mdot+o.mdot=0;
   mdot = i.mdot;
-  o.z = i.z - H "Elevation propagation: outlet is H below inlet";
+  o.elevation.z = i.elevation.z - H "Elevation propagation: outlet is H below inlet";
   annotation (preferredView="info", Documentation(info="<html>
     <p>Two of the draft tubes are modeled using <em>Momentum balance</em>.
     They are:</p>
diff --git a/OpenHPL/Waterway/Fitting.mo b/OpenHPL/Waterway/Fitting.mo
@@ -53,7 +53,7 @@ equation
   o.p = i.p - dp "Pressure of the output connector";
   i.mdot+o.mdot = 0 "Mass balance";
   mdot = i.mdot "Flow direction";
-  o.z = i.z "Elevation propagation: no height change across fitting";
+  o.elevation.z = i.elevation.z "Elevation propagation: no height change across fitting";
   annotation (preferredView="info",
     Documentation(info="<html>
     <p>Various possibilities of the fittings for the pipes with different diameters
diff --git a/OpenHPL/Waterway/Gate.mo b/OpenHPL/Waterway/Gate.mo
@@ -51,7 +51,7 @@ equation
   mdot = Vdot * data.rho "Mass flow rate through the gate";
   i.p = h_0 * data.g * data.rho + data.p_a "Inlet water pressure";
   o.p = h_2 * data.g * data.rho + data.p_a "Outlet water pressure";
-  o.z = i.z "Elevation propagation: gate at same elevation";
+  o.elevation.z = i.elevation.z "Elevation propagation: gate at same elevation";
   annotation (
     preferredView="info",
     Documentation(info="<html>
diff --git a/OpenHPL/Waterway/Gate_HR.mo b/OpenHPL/Waterway/Gate_HR.mo
@@ -50,7 +50,7 @@ equation
   mdot = Vdot * data.rho "Mass flow rate through the gate";
   i.p = h_i * data.g * data.rho + data.p_a "Inlet water pressure";
   o.p = h_o * data.g * data.rho + data.p_a "Outlet water pressure";
-  o.z = i.z "Elevation propagation: gate at same elevation";
+  o.elevation.z = i.elevation.z "Elevation propagation: gate at same elevation";
   annotation (
     preferredView="info",
     Documentation(info="<html>
diff --git a/OpenHPL/Waterway/OpenChannel.mo b/OpenHPL/Waterway/OpenChannel.mo
@@ -39,7 +39,7 @@ equation
 // presurre boundaries
   i.p = h[1] * data.g * data.rho + data.p_a;
   o.p = h[N] * data.g * data.rho + data.p_a;
-  o.z = i.z - (H[1] - H[2]) "Elevation propagation: channel bed drops from H[1] to H[2]";
+  o.elevation.z = i.elevation.z - (H[1] - H[2]) "Elevation propagation: channel bed drops from H[1] to H[2]";
   annotation (preferredView="info",
     Documentation(info="<html>
 <p style=\"color: #ff0000;\"><em>Note: Currently under investigation for plausibility.</em></p>
diff --git a/OpenHPL/Waterway/Penstock.mo b/OpenHPL/Waterway/Penstock.mo
@@ -83,7 +83,7 @@ equation
   // volumetric flow rates for all cells
   V_p_out = mdot ./ rho_m;
   V_p_out_end = mdot_V / (data.rho * (1 + data.beta * (p_o - data.p_a)));
-  o.z = i.z - H "Outlet elevation is H below inlet";
+  o.elevation.z = i.elevation.z - H "Outlet elevation is H below inlet";
   annotation (preferredView="info",
     Documentation(info="<html><head></head><body><p>This is a more detaied model of the pipe that can be use for proper modeling of penstock. (This model does not work well. Instead PenstockKP model can be used.)</p><p>The model for the penstock with the elastic walls and compressible water with simple discretization method (Staggered grid). The geometry of the penstock is described due to figure:</p>
 <p><img src=\"modelica://OpenHPL/Resources/Images/pipe.svg\"></p>
diff --git a/OpenHPL/Waterway/PenstockKP.mo b/OpenHPL/Waterway/PenstockKP.mo
@@ -115,7 +115,7 @@ equation
   S_[N + 1:2 * N] = F_ap * data.g * H / L - F_f / dx;
   // diff. equation
   der(U) = KP.diff_eq;
-  o.z = i.z - H "Outlet elevation is H below inlet";
+  o.elevation.z = i.elevation.z - H "Outlet elevation is H below inlet";
   annotation (preferredView="info",
     Documentation(info="<html>
 <h4>Elastic Penstock with KP Method</h4>
diff --git a/OpenHPL/Waterway/Pipe.mo b/OpenHPL/Waterway/Pipe.mo
@@ -73,7 +73,7 @@ equation
   p_o = o.p "Outlet pressure";
   i.mdot+o.mdot = 0 "Mass balance";
   mdot = i.mdot "Inlet direction for mdot";
-  o.z = i.z - H "Elevation propagation: outlet is H below inlet";
+  o.elevation.z = i.elevation.z - H "Elevation propagation: outlet is H below inlet";
 
   annotation (preferredView="info",
     Documentation(info="<html>
diff --git a/OpenHPL/Waterway/Reservoir.mo b/OpenHPL/Waterway/Reservoir.mo
@@ -6,7 +6,7 @@ model Reservoir "Model of the reservoir"
     annotation (Dialog(group="Setup", enable=not useLevel));
   parameter Boolean fixElevation=false "If true (fixed), z_0 is enforced as initial value; if false (derived), elevation is determined by connected topology"
     annotation (Dialog(group="Geometry"), choices(checkBox=true));
-  parameter SI.Height z_0=0 "Elevation of the reservoir outlet (sets absolute reference)"
+  parameter SI.Position z_0=0 "Elevation of the reservoir outlet (sets absolute reference)"
     annotation (Dialog(group="Geometry", enable=fixElevation));
   parameter Boolean constantLevel=false "If checked, the reservoir keeps the constant water level h_0"
     annotation (
@@ -42,7 +42,7 @@ model Reservoir "Model of the reservoir"
   SI.Momentum M "Water momentum";
   SI.Force F_f "Friction force";
   SI.Height h "Water level";
-  SI.Height h_abs = h + o.z "Absolute water level";
+  SI.Height h_abs = h + o.elevation.z "Absolute water level";
   SI.Pressure p_o "Outlet pressure";
 
   OpenHPL.Interfaces.Contact_o o(p = p_o, showElevation = data.showElevation) "Outflow from reservoir" annotation (Placement(transformation(extent={{90,-10},{110,10}}), iconTransformation(extent={{90,-10},{110,10}})));
@@ -83,8 +83,13 @@ equation
 
    o.mdot = -data.rho * Vdot_o "Output flow connector";
   if fixElevation then
-    o.z = z_0 "Set absolute elevation at outlet";
-    o.gz = 0 "Elevation reference: this component is the root of the connected elevation set";
+    Connections.root(o.elevation) "This reservoir is the definite elevation reference root";
+    o.elevation.z = z_0 "Set absolute elevation at outlet";
+  else
+    Connections.potentialRoot(o.elevation) "May become root if no other component defines the elevation";
+    if Connections.isRoot(o.elevation) then
+      o.elevation.z = 0 "Default elevation when this reservoir is automatically selected as root";
+    end if;
   end if;
   //o.T = T_0 "TBD: Output temperature connector";
   annotation (preferredView="info", Documentation(info="<html>
diff --git a/OpenHPL/Waterway/ReservoirChannel.mo b/OpenHPL/Waterway/ReservoirChannel.mo
@@ -11,7 +11,7 @@ model ReservoirChannel "Reservoir model based on open channel model"
   parameter SI.Height H[2] = {2, 2} "Reservoir bed height from left and right side";
   // initialization
   parameter SI.Height h_0=50 "Initial water level of the reservoir";
-  parameter SI.Height z_0=0 "Elevation of the reservoir outlet"
+  parameter SI.Position z_0=0 "Elevation of the reservoir outlet"
     annotation (Dialog(group="Geometry"));
   parameter Boolean fixElevation=true "If true (fixed), z_0 is enforced as initial value; if false (derived), elevation is determined by connected topology"
     annotation (Dialog(group="Geometry"), choices(checkBox=true));
@@ -35,8 +35,13 @@ equation
   o.mdot =-q*W*data.rho;
   o.p = data.p_a + data.rho * data.g * openChannel.h[N];
   if fixElevation then
-    o.z = z_0 "Set absolute elevation at outlet";
-    o.gz = 0 "Elevation reference: this component is the root of the connected elevation set";
+    Connections.root(o.elevation) "This reservoir is the elevation reference root";
+    o.elevation.z = z_0 "Set absolute elevation at outlet";
+  else
+    Connections.potentialRoot(o.elevation) "May become root if no other root exists";
+    if Connections.isRoot(o.elevation) then
+      o.elevation.z = 0 "Default elevation if this becomes root";
+    end if;
   end if;
   annotation (
     Documentation(preferredView="info", info="<html>
diff --git a/OpenHPL/Waterway/SurgeTank.mo b/OpenHPL/Waterway/SurgeTank.mo
@@ -55,7 +55,7 @@ model SurgeTank "Model of the surge tank/shaft"
   SI.Pressure p_b "Pressure at bottom of the surge tank";
   Real phiSO "Dimensionless factor based on the type of fitting ";
   SI.Height h(start = h_0) "Water height in the surge tank";
-  SI.Height h_abs = h + o.z "Absolute water level";
+  SI.Height h_abs = h + o.elevation.z "Absolute water level";
   SI.VolumeFlowRate Vdot(start = Vdot_0, fixed=true) "Volume flow rate";
 
   Interfaces.Contact_i creek(
@@ -149,7 +149,7 @@ equation
     end if;
     p_t = data.p_a;
   end if;
-  o.z = i.z "Elevation at surge tank inlet and outlet are equal";
+  o.elevation.z = i.elevation.z "Elevation at surge tank inlet and outlet are equal";
  annotation (preferredView="info",
     Documentation(info="<html>
 <h4>Surge Tank Model</h4>
diff --git a/OpenHPL/Waterway/VolumeFlowSource.mo b/OpenHPL/Waterway/VolumeFlowSource.mo
@@ -13,9 +13,9 @@ model VolumeFlowSource "Volume flow source (either fixed or variable)"
     annotation (Dialog(enable=useInput and useFilter));
   parameter Boolean fixElevation=false "If true (fixed), z_0 is enforced as initial value; if false (derived), elevation is determined by connected topology"
     annotation (Dialog(group="Geometry"), choices(checkBox=true));
-  parameter SI.Height z_0=0 "Elevation of the outlet connection"
+  parameter SI.Position z_0=0 "Elevation of the outlet connection"
     annotation (Dialog(group="Geometry", enable=fixElevation));
-  Interfaces.Contact_o o "Outlet flow connector"
+  Interfaces.Contact_o o(showElevation = data.showElevation)  "Outlet flow connector"
     annotation (Placement(transformation(extent={{90,-10},{110,10}})));
   Modelica.Blocks.Interfaces.RealInput outFlow if useInput "Conditional input for defining the outlet flow [m3/s]"
     annotation (Placement(transformation(extent={{-140,-20},{-100,20}})));
@@ -40,8 +40,13 @@ equation
       pattern=LinePattern.Dot));
   o.mdot = -data.rho*Vdot;
   if fixElevation then
-    o.z = z_0 "Set absolute elevation at outlet";
-    o.gz = 0 "Elevation reference: this component is the root of the connected elevation set";
+    Connections.root(o.elevation) "This source is the elevation reference root";
+    o.elevation.z = z_0 "Set absolute elevation at outlet";
+  else
+    Connections.potentialRoot(o.elevation) "May become root if no other root exists";
+    if Connections.isRoot(o.elevation) then
+      o.elevation.z = 0 "Default elevation if this becomes root";
+    end if;
   end if;
   connect(constantVolumeFlow.y, Vdot) annotation (Line(points={{-39,40},{40,40},{40,0},{80,0}}, color={0,0,127}));
   connect(firstOrder.u, outFlow) annotation (Line(
@@ -66,4 +71,4 @@ or via the input connector <code>inFlow</code>.
 In addition the input can be passed through a first order filter which is sometimes necessary
 for numerical reasons depending on the nature of the input data stream.
 </html>"));
-end VolumeFlowSource;
+end VolumeFlowSource;
