implement constraint on max. half-ring length

[nesnoj]

Currently, max. ring length is set to 60km, this might result in half-ring lengths of >30km.
Add max. half-ring length of 28km as constraint (30km according to FGH) - 2km for branching stubs.

[nesnoj]

Solved in 4fe5124.
However, some MVGD show longer half-rings than 28/30km (e.g. 3093) since this constraint is taken into account during improvements only and not in the savings method. This is how it is supposed to work because otherwise, very far nodes could not be connected at all.
This new method will have a large impact on results.

@gplssm: please generate a new dataset (we could talk about it tomorrow in natura). Please notify when it is done.
@abokam, @miguelparadacontzen: as soon as the new data has been generated, you may update your statistics.

[gplssm]

Yep, I can do that!

[nesnoj]

@gplssm Important: Please close CircuitBreakers prior to export, otherwise the lines to the CBs won't be exported! (see also openego/eDisGo#23)

[gplssm]

I included closing of CB's for example_multiple_grid_districts.py in 6a79d84.

Would it be wise to include this as 13th step of run_dingo() rather than doing it at multiple locations?

[nesnoj]

Good point, done in 41a0956.
@abokam Please be aware that all data exported in the next run include closed rings! Please open switch disconnectors / circuit breakers manually if needed.

[gplssm]

Thanks! Since 41a0956 introduces grids with closed rings are returned by run_ding0(), we can remove ring closing from the examples, right?

Is anything more to do here? Otherwise we can close it and soon launch v0.1.3-:rocket:

[nesnoj]

Yepp, could you please remove it?
I think there's nothing else to do.
I like your rocket 🚀 but there're some more tasks in #228 😸

(please close this one as soon as you have adjusted the examples)