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Warnings when simulating examples from ThermoSysPro Library
Warnings when simulating examples from ThermoSysPro Library
Hi,
When trying to simulate examples from the ThermoSysPro library, there are a lot of warnings getting displayed.
One of the warnings is,
[C:\OpenModelica1.9.1Nightly\lib\omlibrary\ThermoSysPro 3.0\Properties\WaterSteam\IF97_packages.mo:801:9-801:27] Warning: cv was used before it was defined (given a value). Additional such uses may exist for the variable, but some messages were suppressed.
Why does this happen?
My Second query is when i simulate ThermoSysPro.Examples.SimpleExamples.TestTank, the simulation proceeds till some % and gets stuck there. The simulation output window shows the following
stdout | info | Chattering detected around time 90.2576262007..90.457032454 (100 state events in a row with a total time delta less than the step size 2). This can be a performance bottleneck. Use -lv LOG_EVENTS for more information. The zero-crossing was: PerteDP1.Q > 0.0 Debug more
What is chattering? Can I have some iformation as to why this happens?
Thanks in advance,
Sanjay
Thank you
Re: Warnings when simulating examples from ThermoSysPro Library
The warning in functions is because some variables in those functions are not defined properly (there is no default=0 in Modelica). As such, some inputs of those functions give undefined results. The functions in question were copy-pasted from an earlier MSL version. Current MSL fixed all those warnings.
Chattering is a state event switching rapidly. Like
model M
Real r(start=1,fixed=true);
equation
der(r) = if r>0 then -1 else 1;
end M;
It is pretty much impossible to get numerical accuracy for that model...
- sjoelund.se
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Re: Warnings when simulating examples from ThermoSysPro Library
I have a follow up question.
The examples in ThermoSysPro.Examples.CombinedCyclePowerPlant when simulated say they are under-determined. Any idea as to how to make the system a determined one?
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