id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
5124	Very simple model is detected as over-determined	tknodt@…	Lennart Ochel	"The following example model fails (28 equations and 26 variables):

{{{
model Test
  model tp
    extends Modelica.Electrical.Analog.Interfaces.TwoPort;
  equation
    connect(n1, n2);
    connect(p1, p2);
  end tp;

  Modelica.Electrical.Analog.Sources.ConstantVoltage v;
  Modelica.Electrical.Analog.Basic.Ground g1;
  Modelica.Electrical.Analog.Sources.ConstantCurrent c(I = 0);
  Test.tp pt;
equation
  connect(g1.p, v.n);
  connect(pt.p1, v.p);
  connect(pt.n1, v.n);
  connect(pt.p2, c.p);
  connect(pt.n2, c.n);
end Test;
}}}

When removing the TwoPort in the middle, it works.
{{{
model Test
  Modelica.Electrical.Analog.Sources.ConstantVoltage v;
  Modelica.Electrical.Analog.Basic.Ground g1;
  Modelica.Electrical.Analog.Sources.ConstantCurrent c(I = 0);
equation
  connect(g1.p, v.n);
  connect(v.p, c.p);
  connect(v.n, c.n);
end Test;
}}}

When manually inlining the TwoPort, I get:
{{{
model Test
  model tp
      Modelica.SIunits.Voltage v1;
      Modelica.SIunits.Voltage v2;
      Modelica.SIunits.Current i1;
      Modelica.SIunits.Current i2;
      Modelica.Electrical.Analog.Interfaces.PositivePin p1;
      Modelica.Electrical.Analog.Interfaces.NegativePin n1;
      Modelica.Electrical.Analog.Interfaces.PositivePin p2;
      Modelica.Electrical.Analog.Interfaces.NegativePin n2;
    equation
      v1 = p1.v - n1.v;
      v2 = p2.v - n2.v;
      0 = p1.i + n1.i;
      0 = p2.i + n2.i;
      i1 = p1.i;
      i2 = p2.i;
      connect(n1, n2);
      connect(p1, p2);
  end tp;

  Modelica.Electrical.Analog.Sources.ConstantVoltage v;
  Modelica.Electrical.Analog.Basic.Ground g1;
  Modelica.Electrical.Analog.Sources.ConstantCurrent c(I = 0);
  Test.tp pt;
equation
  connect(g1.p, v.n);
  connect(pt.p1, v.p);
  connect(pt.n1, v.n);
  connect(pt.p2, c.p);
  connect(pt.n2, c.n);
end Test;
}}}
This has the same result as with the non-inlined version.
When I remove the 0=p1.i+n1.i and 0=p2.i+n2.i equations, it works.
Example:
{{{
model Test
  model tp
      Modelica.SIunits.Voltage v1;
      Modelica.SIunits.Voltage v2;
      Modelica.SIunits.Current i1;
      Modelica.SIunits.Current i2;
      Modelica.Electrical.Analog.Interfaces.PositivePin p1;
      Modelica.Electrical.Analog.Interfaces.NegativePin n1;
      Modelica.Electrical.Analog.Interfaces.PositivePin p2;
      Modelica.Electrical.Analog.Interfaces.NegativePin n2;
    equation
      v1 = p1.v - n1.v;
      v2 = p2.v - n2.v;
      i1 = p1.i;
      i2 = p2.i;
      connect(n1, n2);
      connect(p1, p2);
  end tp;

  Modelica.Electrical.Analog.Sources.ConstantVoltage v;
  Modelica.Electrical.Analog.Basic.Ground g1;
  Modelica.Electrical.Analog.Sources.ConstantCurrent c(I = 0);
  Test.tp pt;
equation
  connect(g1.p, v.n);
  connect(pt.p1, v.p);
  connect(pt.n1, v.n);
  connect(pt.p2, c.p);
  connect(pt.n2, c.n);
  annotation(
      uses(Modelica(version = ""3.2.2""))
    );
end Test;
}}}

These two equations are practically redundant and should be eliminated/ not be counted."	defect	new	high	Future	Backend