removeSimpleEquations makes trafo models singular

[Rüdiger Franke]

After #3195 has been solved and #3274 makes some progress, the next problem seems to be removeSimpleEquations. The AC1ph_DC transformers don't seem to suffer from #3274. The example PowerSystems.Examples.Spot.AC1ph_DC.Transformer fails in the backend. See:

​https://test.openmodelica.org/libraries/PowerSystems/files/PowerSystems.Examples.Spot.AC1ph_DC.Transformer.err

It works if removeSimpleEquations is disabled.

Btw. the online docu lists --postOptModules-. Attempts to use it failed; tried:

setCommandLineOptions("--postOptModules-=removeSimpleEquations");

Would be great if the online docu gave an example for the usage of this option.

[Lennart Ochel]

The command line option --postOptModules-= does work for me. I tested it using the following script:

loadString("
model test
end test;
"); getErrorString();

setCommandLineOptions("--postOptModules-=removeSimpleEquations");
simulate(test); getErrorString();

The post-optimization module is removed from the transformation process. Only the pre-optimization module removeSimpleEquations is still applied.

[Lennart Ochel]

I will add an example to the documentation.
However, can you provide a list of all selected flags? Maybe it is related to a certain combination of flags.

[Rüdiger Franke]

It happens with all kinds of flags. The nightly tests use for instance:

setCommandLineOptions("-d=nogen,initialization,backenddaeinfo,discreteinfo,stateselection,execstat");
setMatchingAlgorithm("PFPlusExt");
setIndexReductionMethod("dynamicStateSelection");

See: ​https://test.openmodelica.org/libraries/PowerSystems/BuildModelRecursive.html

[Rüdiger Franke]

Here is the complete error message for PowerSystems.Examples.Spot.AC1ph_DC.Transformer:

Error: Too few equations, under-determined system. The model has 35 equation(s) and 37 variable(s).
Error: pre-optimization module encapsulateWhenConditions (simulation) failed.

It compiles and simulates with

setCommandLineOptions("--preOptModules-=removeSimpleEquations")

[Volker Waurich]

The problem is that removeSimpleEquations is not consistent on how to assign alias variables in cases like: trafo.w1_set = trafo.W1[1 + trafo.tap_p_internal]
whereas a variable is assigned to a scalar array parameter whose subscribt is a discrete variable. For reasons of simplicity I will try to NOT assign alias variables in that case.

[Volker Waurich]

Pushed the fix in [10507c7]
BTW: Skipping this kind of alias assignments does not occure in any of the msl3.2.1. models.

[Martin Sjölund]

Did it occur in any test in the test suite? If not, perhaps a testcase should be added?

[Volker Waurich]

Got 2 more models simulating in PowerSystems. Everything else seems stable.

@sjoelund.se:
It does not occur in the testsuite. Would be good to test PowerSystems.Examples.Spot.AC1ph_DC.Transformer somewhere but PowerSystems is not available for the Hudson testsuite, isnt it?

[Martin Sjölund]

Create a total model (should not be many kilobytes, right?). Then you don't have problems when the libraries change.

[Martin Sjölund]

It is also possible to add it to the gitlibraries portion of the test suite (which is run by the pull request job, but only on a flag in runtests.pl):

OpenModelica/testsuite/simulation/libraries/3rdParty/GitLibraries

[Volker Waurich]

Replying to sjoelund.se:

Create a total model (should not be many kilobytes, right?). Then you don't have problems when the libraries change.

Any idea how to create a total modal without copy-pasting everything needed? I mean, PowerSystems uses a lot of inheritance it would take some time and its quite annoying to gather every model that is used.

[Adrian Pop]

Via a script:

loadModel(Modelica); getErrorString();
loadModel(PowerSystems); getErrorString();
saveTotalSCode("TotalModel.mo", PowerSystems.Examples.Spot.AC1ph_DC.Transformer);

will give you TotalModel.mo containing everything you need.
You can also do it from OMEdit.

[Volker Waurich]

Replying to adrpo:

Via a script:

loadModel(Modelica); getErrorString();
loadModel(PowerSystems); getErrorString();
saveTotalSCode("TotalModel.mo", PowerSystems.Examples.Spot.AC1ph_DC.Transformer);

will give you TotalModel.mo containing everything you need.
You can also do it from OMEdit.

Thats pretty cool. Thanks for the hint.

[Adrian Pop]

You can use also saveTotalModel instead of saveTotalSCode:
​https://build.openmodelica.org/Documentation/OpenModelica.Scripting.saveTotalSCode.html

[Volker Waurich]

Added a testcase, i.e. the trafo model.

[Rüdiger Franke]

Overall 3 more PowerSystems models translate now (2 more simulate), including also the 3-phase PowerSystems.Examples.Spot.TransformationAC3ph.TapChanger!

Thanks :)

[Martin Sjölund]

Milestone deleted