Hi Dominic, I am working on a similar problem and I’ve tested your workaround, I can confirm that results are essentially the same. I cannot explain why, but I get a difference that is perfectly negligible (order of 1e-11). In addition I would like to seize the opportunity and ask you for information, given the similarity of our problems: in your case do the wind generators follow the profiles set as input? I mean in the dispatch is the output “res” power comparable to the profiles one? Thanks in advance, Regards, Antonio L’Abbate Inviato da Posta per Windows 10
Da: Hewes, Dominic Inviato: martedì 7 maggio 2019 12:21 A: MATPOWER-L@cornell.edu Oggetto: Question regarding min up/down constraints in MOST Dear Matpower community, I am working with a relatively large model ( approximately 1000 conventional generators and 4000 wind generators) and am solving a multi-period deterministic unit commitment problem (with DC model) in MOST. The problem requires a significant amount of time during the setup phase in MOST (i.e. mdo.results.SetupTime). The vast majority of this setup time seems to be related to the addition of the minimum up and down time constraints within the om struct (lines 1538 to 1591 in most.m) and the processing of these constraints in the om.params_lin_constraint() call (line 1974 in most.m). It seems like these constraints are applied for all wind generators, even though the minup/mindown values are set to 1 for all wind gens, and this costs a large amount of setup time. Since the xgd.MinUp and xgd.MinDown values are set to 1, I would assume that the constraints are not required. My question is: If a generator has a minup/mindown limit set to 1 (i.e. no limit), does it meaningfully change the problem in MOST if I simply skip the minup/mindown constraints for this generator (i.e. do not add the constraints defined in lines 1538 to 1591 in most.m)? I have tried this out using a simple test, where the minup/mindown limits for all gens are set to 1 (i.e. xgd.MinUp(:)=1). I run the most.m script in original form and then with lines 1538 to 1591 commented out. Ultimately, I get either the exact same solution or something very very close in the simulations with and without the minup/mindown constraints. In some cases, the result has almost the exact same price, but the dispatch seems to be allocated slightly differently between similarly priced generators located at the same nodes (i.e. the result is effectively the same). Could someone explain why these small differences occur between the results? Does this indicate that the skipping of minup/mindown constraints has caused problems elsewhere in most.m and I should therefore avoid this approach? Any help with these questions would be greatly appreciated. Regards, Dominic
