Using "Save start values in the model" option to help the convergence in Dymola

Question

I build a model in dymola. Even though there are some errors during the initialization process, but the calculation succeeded at last.

After the model converged successfully, I tried to use the "Save start values in the model" option to get the right iteration variable strat values stored into the model so that the model would NOT get errors in the next calculation. But after I did this and tried to do calculation once more, I still got the same errors.

So, my question is: Could I use the "Save start values in the model" to help convergence? If so, how should I do it?

Answer 1

Are you certain that there are error messages?

The simulation log indicates that you have enabled Simulation Setup>Debug>Nonlinear iterations

That gives debug messages in the simulation log for every iteration of the non-linear solver, regardless of whether there is a problem or not. (Which can be good for analyzing errors, but should not be on as default as it generates large log-file.)

If disabling that flag doesn't remove all messages, it would be necessary to see the remaining messages and the model to understand the problem; as the previously indicated procedures should work.

Answer 2

The reason is I set the fixed attribute of some parameter as false, the fixed attribute of some variable as true, so I could use the variable's value to initialize the system, and the corresponding parameter would be calculated. when using "save start values in the model" option, it would store the result into the parameter's start attribute, but its value attribute would keep unchanged. When I do simulation again, Dymola would NOT use the parameter's start attribute, it would still use the parameter's value attribute. After I change the value attribute manually, there would be no error anymore.