Aggregated constraint in a VT_file?

[Pernille.S]

Dear VEDA_FE experts,

We have a national VEDA_FE model that is split into five regions. We wish to constrain several resources, for example WASTE, on a national level. As I understood, this is possible by
- a user constraint in a scenario file
- defining trade of this commodity between regions in Trade_Links

Instead of using one of these options, I would like to constrain the use of a given commodity, on a national basis, in a VT_file? Is this possible and how can it be done?

All tips are highly appreciated!

[Antti-L]

I would like to constrain the use of a given commodity, on a national basis, in a VT_file?

I guess that by a VT_file you mean a B-Y template? I don't know any direct way of defining such a constraint for e.g. WASTE there, but only an indirect way: by defining the bound values for the internal VA_Attrib_C attribute, so that VA_Attrib_C(r,WASTE,year)=value. And then in a scenario file one would use a FILL table to get the VA_Attrib_C values and define the corresponding UC_RHST(uc_n,year,'UP')=VA_Attrib_C(r,WASTE,year) (or the sum of these values over some regions). In that way the UC constraint would get the bound value calculated in the B-Y template.

[Pernille.S]

Thank you very much for your fast response and suggestion Antti. Yes, I mean the B-Y-Template.
I believe your suggested approach can be a good way to gather all data regarding commodity resources, prices and import in one excel-file.

[Antti-L]

Well, if you have looked at the VEDA TIMES-Starter model, you can see that in that model links across Excel files have been used for the same purpose.  So, by using external references (links) you can also use one Excel file for all national level calculations, and then refer to the data in that Excel file in other VEDA templates.

Using such external links in the templates may, however, slow down a bit VEDA when the templates are processed (if VEDA attempts to updated them automatically, I am not sure), and/or you need to manually update the referring Excel files whenever the data is changed.  I have not been using external links in my own model templates, but as they are heavily used in the Starter model, I guess they work quite well.