Add case118Blumsack

[salvapineda]

Description

Add case118Blumsack.mat file. This is a classical system used in transmission switching models proposed in 2006 by Blumsack (https://www.cmu.edu/ceic/assets/docs/publications/phd-dissertations/2006/seth-blumsack-phd-thesis-2006.pdf)

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[simonbowly]

@salvapineda thanks for your contributions.

The datasets included with the optimods package are intended as quick demos to make the examples in the documentation easy to run. Ideally I would rather not add additional files to the distribution; users can read additional OPF cases using read_case_matpower.

Is this .mat file (or any others of interest) available from a public link somewhere? If so, I would rather that we share it as a reference in the optimods documentation instead of including the file directly.

[salvapineda]

I see your point. The thing is that in most matpower cases the rateA of all branches is set to 0 and therefore, the swithing problem is not relevant. Since the 118Blumsack is commonly used, I thought it could be interesting to have at least one medium size instance to test switching problems. I looked for references but couldn't find any official one. I found this one (https://sites.google.com/site/burakkocuk/research) where you can find it under the instances of the work "A Cycle-Based Formulation and Valid Inequalities for DC Power Transmission Problems with Switching". I also created a repository with the data: https://github.com/salvapineda/case118blumsack. So use the one you prefer. Thanks!