Hi Felix,
you're analysis is quite correct.
In PyPSA-Eur, you should take s_nom_opt - s_nom_min for the calculation
of line expansion.
The reason is that indeed s_nom gets new values when calling the
function n.ilopf(), which iteratively solves lopf while adjusting line
impedances to line expansion. This is intended.
Best wishes,
Fabian N
On 10.08.22 19:09, Felix Delgado Elizundia wrote:
> Hello! I hope you are well
>
> I wanted to ask a quick question regarding the expansion of transmission
> lines and links. and particularly s_nom and s_nom_opt.
>
> I have done the exercise as is shown in the tutorial, where to calculate
> the expansion of the lines you substract *n.lines.s_nom_opt* minus
> *n.lines.s_nom. *However this results in minimal differences (1e-13) and
> only in some cases and noticed that the sum of *n.lines.s_nom_opt* is
> the same as the sum *n.lines.s_nom. Implying no real change*
>
> I wanted to understand, especially because while using the plotting
> function, I could see the some lines where expanded heavily.
> I noticed that in the plot_network.py script *s_nom_opt* is plotted
> against *s_nom_min*. And indeed by checking, as seen in the image below,
> *s_nom_min* is lower than both *s_nom_op*t and*s_nom.*
>
> In this sense I wanted to ask the following questions.
>
> * How is it that *s_nom_min* can be lower than *s_nom *(in some cases
> 0) and the same as s_nom_opt? I understand that lines can only be
> expanded and that s_nom_min was set at the value of s_nom. Could the
> optimization be overwriting the s_nom value?
> * To calculate line expansion during the optimization, should I use
> *s_nom_min* instead?
>
> Would love to hear if you have any insights or clarity on my questions
> and thank you in advance. have a great evening!
>
>
> Screenshot 2022-08-10 185714.png
>
> Screenshot 2022-08-10 190809.png
>
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Technische Universität Berlin
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