Models of trunk/Modelica that do not simulate in OpenModelica (and are not present in MSL 3.2.1 failed simulations)

[martin.otter@…]

When comparing the simulation results of MSL 3.2.1 with trunk:

​https://test.openmodelica.org/hudson/job/MSL_3.2.1_Simulation/894/#showFailuresLink, Build #894 (Feb 28, 2016 8:17:37 AM)

with

​https://test.openmodelica.org/hudson/job/MSL_trunk_Simulation/860/#showFailuresLink, Build #860 (Feb 28, 2016 8:22:08 AM)

then the following models are either not present in MSL 3.2.1 or simulate in MSL 3.2.1 but not in trunk:

Modelica.Electrical.Analog.Examples.OpAmps.SignalGenerator
- Fails with DASSL (nonlinear equation solver fails)
- Simulates with Radau5
    
Modelica.Electrical.Analog.Examples.OpAmps.Multivibrator
- Fails with DASSL and Radau5 (nonlinear equation solver fails)
- Simulates with trapezoid
     Modelica.Electrical.Machines.Examples.SynchronousInductionMachines.SMPM_Braking
- Fails with DASSL, Radau5, Trapezoid (nonlinear equation solver fails)
- Simulates in Dymola, but with a
  WARNING: You have many state events. It might be due to chattering.
  Changing Vknee in the diodes from 0 to 0.8 (= more realistic diode model)
  removes the chattering warning in Dymola (and about 5 times less state events).
       Modelica.Magnetic.FundamentalWave.Examples.BasicMachines.AIMC_DOL_MultiPhase
- Fails with DASSL, Radau5, Trapezoid (nonlinear equation solver fails)
      Modelica.Magnetic.FundamentalWave.Examples.BasicMachines.SMPM_Inverter_MultiPhase
- Fails with DASSL, Radau5, Trapezoid (nonlinear equation solver fails)
        Modelica.Magnetic.FundamentalWave.Examples.BasicMachines.SMR_Inverter_MultiPhase
- Fails with DASSL, Radau5, Trapezoid (linear equation solver fails)
    
Modelica.Fluid.Examples.IncompressibleFluidNetwork
- Compilation took too long, so I stopped.
- Unclear, because the last change of this model was in 2013, and then this
      model should fail with MSL 3.2.1 and with trunk, but it fails only in trunk

[martin.otter@…]

In all the models it seems that nonlinear or linear algebraic loops cannot be solved. In Dymola all these models simulate and the log does not show an issue.

The messages from OpenModelica seem to indicate that algebraic loops are singular. The reason can either be that index reduction fails (so the index reduction does not recognize that there are constraints), or the algebraic solvers are not good enough, or there is really a singular system and Dymola solves it in a least squares sense (so picks one solution of the infinitely many that is closes to the previous solution, but OpenModelica does not.

[Martin Sjölund]

Milestone pushed to 1.9.5

[Martin Sjölund]

Milestone renamed

[Martin Sjölund]

Ticket retargeted after milestone closed

[Martin Sjölund]

Milestone moved to 1.12.0 due to 1.11.0 already being released.

[Francesco Casella]

The milestone of this ticket has been reassigned to "Future".

If you think the issue is still valid and relevant for you, please select milestone 1.13.0 for back-end, code generation and run-time issues, or 2.0.0 for front-end issues.

If you are aware that the problem is no longer present, please select the milestone corresponding to the version of OMC you used to check that, and set the status to "worksforme".

In both cases, a short informative comment would be welcome.