Simulink error - Unconverged equations

Hi, I have built a model of a wind turbine using simscape, connected to an electrical system consisting of a grid voltage and grid impedance. I run the model with variable step using solver ote23 with a maximum time step of 10e-6 and the model works. I am trying to connect this to a model which was provided externally to me, of an AC/DC converter and DC load. This external model works on its own (When I run the file of that model) using variable step size with a maximum timstep of 10e-6 and solver ote23.

But when I try and connect this external model to my model with wind turbine and grid, I am met with errors of 'unconverged equations' which are the grid inductance and the capacitance in the external AC/DC converter. I'm confused as these models work independently of eachother with the same solver settings but when ran in the same model I am always getting this error. Any help would be much appreciated, I'd be happy to explain a bit more or upload screenshots if required.

Thanks :)

Answer 1

[Piyush Patil]

Hello Paul

It's possible that the two models working together are producing numerical problems that don't exist when they run separately. Since both models work individually, it's possible that the issue is with how they are being connected together.

Here are few suggestions that you could try to resolve the error -

1. Try reducing the maximum time step to see if a smaller time step helps the simulation converge.
2. Try using different solver, such as "ode15s" or "ode23tb" for the combined model.
3. Check that the physical units of the inputs and outputs between the two models are consistent.

If the issue still persists, then please share some more information about your model. It will allow me to better understand the issue so that I can assist you in resolving it.