Choosing line parameters

[amparocorvalan]

Hi,

I wanted to ask you how you chose the parameters of the models, specifically of the lines, since by making small modifications my model stops running, presents boundary problems and the model fails to initialize. How do you choose the parameters of the lines, in particular, r, x and b for different voltage levels? The same for the value of trans when using transformers.

I also do not understand why there are negative values of x in the lines of the wecc_full model.

Thank you in advance!

Amparo