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modelicadymola
Jack
Jack

Reputation: 1232

How to ensure convergence during the initialization of the nonlinear system in Dymola

Is there a guide for increasing the ability of convergence during the initialization of the nonlinear system in Dymola? Usually, the connector contains start values, but they are not always suited for the model I build, so there might be a divergence issue during the initialization. How could I avoid this issue?

Upvotes: 0

Views: 189

Answers (2)

Jack
Jack

Reputation: 1232

By comparing two different power plant libraries, I think the best practice is to set the start values of each attribute of every connector in the component in the initial equation part. If so, despite that dymola choose which variable as the iteration variable, it would ensure convergence.

Here is a simple example I answered in another question: Non-liner solver couldn't converge during the initialization in Dymola

Upvotes: 0

marco
marco

Reputation: 6655

The Dymola User Manual Volume 1 has several chapters, which deal with the initialization of nonlinear systems. In Dymola 2020 the chapters are:

5.6.8 Initial guesses for nonlinear equations in the model during simulation
5.8.3 Discriminating start values
5.8.4 Debugging failed initialization

You can also try to provide min and max values for certain variables and activate the check during simulation, as described in

5.6.10 Bound checking for variables

Upvotes: 2

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