id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
5185	Simulating a pure algebraic model in daeMode leads to a wrong solution	Francesco Casella	Willi Braun	"The DistributionSystemModelica_N_X_M_X models of the ScalableTestSuite run with {{{daeMode = new}}} badly fail the verification phase, see e.g. [https://libraries.openmodelica.org/branches/daemode/ScalableTestSuite_noopt/files/ScalableTestSuite_noopt_ScalableTestSuite.Electrical.DistributionSystemDC.ScaledExperiments.DistributionSystemModelica_N_10_M_10.diff.html this report]. Analysis of the results reveal that despite {{{V_source.v}}} correctly ramping up to 600 V, all voltages and currents in the distribution networks turn out to be zero.

You can replicate the issue with a much simpler model:
{{{
model Test
  extends ScalableTestSuite.Electrical.DistributionSystemDC.ScaledExperiments.DistributionSystemModelica_N_10_M_10
   (N = 1, M = 1);

annotation(
  experiment(StopTime = 1, Interval = 1e-3),
  uses(ScalableTestSuite(version = ""1.11.4"")),
  __OpenModelica_commandLineOptions = ""-d=optdaedump --daeMode=new"");
end Test;
}}}
which feature the series connection of the voltage source {{{V_source}}}, the resistor {{{primary}}}, the resistor {{{secondary}}}, and the resistor {{{load}}}, which is eventually connected to ground. As soon as the voltage source is ramped up, all voltages are expected to grow and current to flow in the series connection. Instead, in the simulation results, {{{primary[1].v}}} is identically zero, so no current flows, and then everything else is zero accordingly.

The last step of {{{optdaedump}}} outputs the following equations
{{{
Variables (9) 
======================================== 
1: V_source.v:VARIABLE(unit = ""V"" )  ""Voltage drop between the two pins (= p.v - n.v)"".Test, .Modelica.Electrical.Analog.Sources.RampVoltage$V_source type: Real  
2: $DAEres0:DAE_RESIDUAL_VAR()  type: Real  
3: $DAEres1:DAE_RESIDUAL_VAR()  type: Real  
4: $DAEres2:DAE_RESIDUAL_VAR()  type: Real  
5: $DAEres3:DAE_RESIDUAL_VAR()  type: Real  
6: $DAEres4:DAE_RESIDUAL_VAR()  type: Real  
7: primary[1].LossPower:VARIABLE(unit = ""W"" )  ""Loss power leaving component via heatPort"".Test, .Modelica.Electrical.Analog.Basic.Resistor$primary type: Real  [1] 
8: load[1,1].LossPower:VARIABLE(unit = ""W"" )  ""Loss power leaving component via heatPort"".Test, .Modelica.Electrical.Analog.Basic.Resistor$load type: Real  [1,1] 
9: secondary[1,1].LossPower:VARIABLE(unit = ""W"" )  ""Loss power leaving component via heatPort"".Test, .Modelica.Electrical.Analog.Basic.Resistor$secondary type: Real  [1,1] 
 
 
Equations (9, 9) 
======================================== 
1/1 (1): V_source.v := V_source.signalSource.offset + (if time < V_source.signalSource.startTime then 0.0 else if time < V_source.signalSource.startTime + V_source.signalSource.duration then (time - V_source.signalSource.startTime) * V_source.signalSource.height / V_source.signalSource.duration else V_source.signalSource.height)   [auxiliary |1|1|0|1|] 
2/2 (1): $DAEres0 := load[1,1].R_actual * secondary[1,1].i - load[1,1].v   [dynamic |1|0|0|1|] 
3/3 (1): $DAEres1 := secondary[1,1].R_actual * secondary[1,1].i - secondary[1,1].v   [dynamic |1|0|0|1|] 
4/4 (1): $DAEres2 := primary[1].n.v + (-load[1,1].v) - secondary[1,1].v   [dynamic |1|0|0|1|] 
5/5 (1): $DAEres3 := V_source.v + (-primary[1].n.v) - primary[1].v   [dynamic |1|0|0|1|] 
6/6 (1): $DAEres4 := primary[1].R_actual * secondary[1,1].i - primary[1].v   [dynamic |1|0|0|1|] 
7/7 (1): primary[1].LossPower := primary[1].v * secondary[1,1].i   [auxiliary |0|1|0|1|] 
8/8 (1): load[1,1].LossPower := load[1,1].v * secondary[1,1].i   [auxiliary |0|1|0|1|] 
9/9 (1): secondary[1,1].LossPower := secondary[1,1].v * secondary[1,1].i   [auxiliary |0|1|0|1|] 
}}}
Equation 5/5 is correct, and states that the voltage across the source {{{V_source.v}}} should be equal to the sum of the voltage across the primary resistor {{{primary[1].v}}} plus the voltage on its negative pin {{{primary[1].n.v}}}. If you check the simulation results, though, the first voltage ramps up to 600, while the other two remain zero.

I guess something goes wrong in the code generation. Test_16dae.c contains the following lines
{{{
/*
 equation index: 58
 type: SIMPLE_ASSIGN
 $DAEres3 = V_source.v + (-primary[1].n.v) - primary[1].v
 */
void Test_eqFunction_58(DATA *data, threadData_t *threadData)
{
  TRACE_PUSH
  const int equationIndexes[2] = {1,58};
  $P$DAEres3 = data->localData[0]->realVars[0] /* V_source.v variable */ + (-data->localData[0]->realVars[7] /* primary[1].n.v variable */) - data->localData[0]->realVars[8] /* primary[1].v variable */;
  TRACE_POP
}
}}}
which seems correct looking at the comments.

However, the Test_info.json file contains this chunk:
{{{
""variables"":{
""V_source.v"":{""comment"":""Voltage drop between the two pins (= p.v - n.v)"",""kind"":""variable"",""type"":""Real"",""unit"":""V"",""displayUnit"":"""",""source"":{""info"":{""file"":""C:/OpenModelica1.13.0-dev-64bit/lib/omlibrary/Modelica 3.2.2/Electrical/Analog/Interfaces.mo"",""lineStart"":173,""lineEnd"":173,""colStart"":5,""colEnd"":67},""within"":[""Real""],""instance"":""V_source"",""typeLst"":[""Test"",""Modelica.Electrical.Analog.Sources.RampVoltage$V_source""]}},
""load[1,1].LossPower"":{""comment"":""Loss power leaving component via heatPort"",""kind"":""variable"",""type"":""Real"",""unit"":""W"",""displayUnit"":"""",""source"":{""info"":{""file"":""C:/OpenModelica1.13.0-dev-64bit/lib/omlibrary/Modelica 3.2.2/Electrical/Analog/Interfaces.mo"",""lineStart"":312,""lineEnd"":312,""colStart"":5,""colEnd"":67},""within"":[""Real""],""instance"":""load[1,1]"",""typeLst"":[""Test"",""Modelica.Electrical.Analog.Basic.Resistor$load""]}},
""load[1,1].R_actual"":{""comment"":""Actual resistance = R*(1 + alpha*(T_heatPort - T_ref))"",""kind"":""variable"",""type"":""Real"",""unit"":""Ohm"",""displayUnit"":"""",""source"":{""info"":{""file"":""C:/OpenModelica1.13.0-dev-64bit/lib/omlibrary/Modelica 3.2.2/Electrical/Analog/Basic.mo"",""lineStart"":62,""lineEnd"":63,""colStart"":5,""colEnd"":63},""within"":[""Real""],""instance"":""load[1,1]"",""typeLst"":[""Test"",""Modelica.Electrical.Analog.Basic.Resistor$load""],""operations"":[{""op"":""info"",""display"":""solved"",""data"":[""load[1,1].R_actual = load[1,1].R * (1.0 + load[1,1].alpha * (load[1,1].T - load[1,1].T_ref))""]},{""op"":""chain"",""display"":""substitution"",""data"":[""load[1,1].R * (1.0 + load[1,1].alpha * (load[1,1].T_heatPort - load[1,1].T_ref))"",""load[1,1].R * (1.0 + load[1,1].alpha * (load[1,1].T - load[1,1].T_ref))""]},{""op"":""before-after"",""display"":""flattening"",""data"":[""R_actual = R * (1 + alpha * (T_heatPort - T_ref));"",""load[1,1].R_actual = load[1,1].R * (1.0 + load[1,1].alpha * (load[1,1].T_heatPort - load[1,1].T_ref));""]}]}},
""load[1,1].v"":{""comment"":""Voltage drop between the two pins (= p.v - n.v)"",""kind"":""variable"",""type"":""Real"",""unit"":""V"",""displayUnit"":"""",""source"":{""info"":{""file"":""C:/OpenModelica1.13.0-dev-64bit/lib/omlibrary/Modelica 3.2.2/Electrical/Analog/Interfaces.mo"",""lineStart"":173,""lineEnd"":173,""colStart"":5,""colEnd"":67},""within"":[""Real""],""instance"":""load[1,1]"",""typeLst"":[""Test"",""Modelica.Electrical.Analog.Basic.Resistor$load""]}},
""primary[1].LossPower"":{""comment"":""Loss power leaving component via heatPort"",""kind"":""variable"",""type"":""Real"",""unit"":""W"",""displayUnit"":"""",""source"":{""info"":{""file"":""C:/OpenModelica1.13.0-dev-64bit/lib/omlibrary/Modelica 3.2.2/Electrical/Analog/Interfaces.mo"",""lineStart"":312,""lineEnd"":312,""colStart"":5,""colEnd"":67},""within"":[""Real""],""instance"":""primary[1]"",""typeLst"":[""Test"",""Modelica.Electrical.Analog.Basic.Resistor$primary""]}},
""primary[1].R_actual"":{""comment"":""Actual resistance = R*(1 + alpha*(T_heatPort - T_ref))"",""kind"":""variable"",""type"":""Real"",""unit"":""Ohm"",""displayUnit"":"""",""source"":{""info"":{""file"":""C:/OpenModelica1.13.0-dev-64bit/lib/omlibrary/Modelica 3.2.2/Electrical/Analog/Basic.mo"",""lineStart"":62,""lineEnd"":63,""colStart"":5,""colEnd"":63},""within"":[""Real""],""instance"":""primary[1]"",""typeLst"":[""Test"",""Modelica.Electrical.Analog.Basic.Resistor$primary""],""operations"":[{""op"":""info"",""display"":""solved"",""data"":[""primary[1].R_actual = primary[1].R * (1.0 + primary[1].alpha * (primary[1].T - primary[1].T_ref))""]},{""op"":""chain"",""display"":""substitution"",""data"":[""primary[1].R * (1.0 + primary[1].alpha * (primary[1].T_heatPort - primary[1].T_ref))"",""primary[1].R * (1.0 + primary[1].alpha * (primary[1].T - primary[1].T_ref))""]},{""op"":""before-after"",""display"":""flattening"",""data"":[""R_actual = R * (1 + alpha * (T_heatPort - T_ref));"",""primary[1].R_actual = primary[1].R * (1.0 + primary[1].alpha * (primary[1].T_heatPort - primary[1].T_ref));""]}]}},
""primary[1].n.v"":{""comment"":""Potential at the pin"",""kind"":""variable"",""type"":""Real"",""unit"":""V"",""displayUnit"":"""",""source"":{""info"":{""file"":""C:/OpenModelica1.13.0-dev-64bit/lib/omlibrary/Modelica 3.2.2/Electrical/Analog/Interfaces.mo"",""lineStart"":87,""lineEnd"":92,""colStart"":5,""colEnd"":61},""within"":[""Real""],""instance"":""primary[1]n"",""typeLst"":[""Test"",""Modelica.Electrical.Analog.Basic.Resistor$primary"",""Modelica.Electrical.Analog.Interfaces.NegativePin""]}},
""primary[1].v"":{""comment"":""Voltage drop between the two pins (= p.v - n.v)"",""kind"":""variable"",""type"":""Real"",""unit"":""V"",""displayUnit"":"""",""source"":{""info"":{""file"":""C:/OpenModelica1.13.0-dev-64bit/lib/omlibrary/Modelica 3.2.2/Electrical/Analog/Interfaces.mo"",""lineStart"":173,""lineEnd"":173,""colStart"":5,""colEnd"":67},""within"":[""Real""],""instance"":""primary[1]"",""typeLst"":[""Test"",""Modelica.Electrical.Analog.Basic.Resistor$primary""]}},
""secondary[1,1].LossPower"":{""comment"":""Loss power leaving component via heatPort"",""kind"":""variable"",""type"":""Real"",""unit"":""W"",""displayUnit"":"""",""source"":{""info"":{""file"":""C:/OpenModelica1.13.0-dev-64bit/lib/omlibrary/Modelica 3.2.2/Electrical/Analog/Interfaces.mo"",""lineStart"":312,""lineEnd"":312,""colStart"":5,""colEnd"":67},""within"":[""Real""],""instance"":""secondary[1,1]"",""typeLst"":[""Test"",""Modelica.Electrical.Analog.Basic.Resistor$secondary""]}},
}}} 

and if you count the variables from zero (as usual with C records) it seems to me that 
{{{primary[1].n.v}}} and {{{primary[1].v}}} are number 6 and 7, not 7 and 8. I guess that you are mapping Modelica arrays into C arrays without subtracting 1 somewhere in the {{{daeMode=new}}} code generation functions, which also explains why this problem only shows up with vectorized ScalableTestSuite test cases.

Please fix this ASAP, before the 1.13.0 release.

Also, I have to admit I do not fully understand the {{{optdaedump}}} output. The DAE residuals are listed among the unknowns, but they are in fact not unknown at all, as they should be zero at the solution. Conversely, the real unknowns of the corresponding strong component of the BLT, namely {{{primary[1].v}}}, {{{primary[1].n.v}}}, {{{secondary[1,1].v}}}, and {{{secondary[1,1].i}}} do not show up anywhere, which is quite puzzling. Unless I am missing something, please make sure the correct unknowns are listed."	defect	closed	blocker	1.13.0	Run-time		fixed