Thanks Carlos and Ray, I was thinking in changing the code, but for sure, your solutions are much more clean and elegant.
Thanks again, Santiago 2012/10/31 Ray Zimmerman <[email protected]>: > I just saw Carlos' response to your post on MATPOWER-L. His suggestion of a > piecewise linear cost is, of course, even better than my suggestion. I'm not > sure why that didn't occur to me when I was responding. > > -- > Ray Zimmerman > Senior Research Associate > 419A Warren Hall, Cornell University, Ithaca, NY 14853 > phone: (607) 255-9645 > > > > > On Oct 31, 2012, at 12:10 PM, Ray Zimmerman <[email protected]> wrote: > > Actually, I think the easiest way to do it is to model it with two > generators, one for the negative portion of the reactive power output, the > other for the positive. Use a negative cost coefficient for the negative > portion and a positive coefficient for the positive portion. > > -- > Ray Zimmerman > Senior Research Associate > 419A Warren Hall, Cornell University, Ithaca, NY 14853 > phone: (607) 255-9645 > > > > > On Oct 26, 2012, at 5:20 PM, Santiago Torres <[email protected]> > wrote: > > Right, I understand that modeling a cuadratic cost function I could > get always positive costs, for reactive power generation. But, I am > using that in a different way. I am, modeling linear costs (Qg x > reactive Costs) and I want always to have positive costs, for both > inductive power and capacitive power generation. May be there is a > way to do that getting inside the code... I think it is a simple > matter to put some abs command where is located the cost calculation > part.... can you give me advice how to do that?? > > any help is very appreciated > > 2012/10/24 Ray Zimmerman <[email protected]>: > > That depends completely on how you define the cost function. If it is linear > with a positive slope, e.g. Cost = Qg, then it will be negative for negative > injections. If it is quadratic, e.g. Cost = Qg^2, then it will always be > positive. > > --Ray > > > On Oct 24, 2012, at 10:51 AM, Santiago Torres <[email protected]> > wrote: > > Thanks Ray, but I mean, there is no way they are negative costs > right?? It does not make sense... ok? because if you have negative > generation (inductive compensation), maybe you could have negative > costs.... May be is a silly question, but I want to asure that does > not happen (to get negative costs).... > > 2012/10/24 Ray Zimmerman <[email protected]>: > > I'm not sure I understand where your question lies. The cost is still > defined just like for real power injections, as either a polynomial or > piecewise linear function of the injection, specified in the gencost matrix. > > --Ray > > On Oct 23, 2012, at 6:24 PM, Santiago Torres <[email protected]> > wrote: > > Dear Ray, > > First of all, I hope your things are going well. I am not very clear > about the reactive part of AC OPF modeling in MATPOWER. > > The generators have reactive power limits that could be positive or > negative. What about if in some cases there is "negative" power flow > at some generator node. In that case, how will be the costs of > reactive power generation??? How it is managed by matpower? > > I am trying to model shunt compensation as simple generators, with > only variable costs, so I need to be clear with that matter. > > regards > > Santiago > > -- > Dr.-Ing. Santiago Torres > IEEE Senior Member > > Post-Doctoral Fellow > School of Electrical and Computer Engineering > > > University of Campinas, Campinas, SP, Brazil > > http://www.dsee.fee.unicamp.br/ > > Albert Einstein, 400 > 13083-852, Campinas, SP, Brazil > > > > > -- > Dr.-Ing. Santiago Torres > IEEE Senior Member > > Post-Doctoral Fellow > School of Electrical and Computer Engineering > > > University of Campinas, Campinas, SP, Brazil > > http://www.dsee.fee.unicamp.br/ > > Albert Einstein, 400 > 13083-852, Campinas, SP, Brazil > > > > > -- > Dr.-Ing. Santiago Torres > IEEE Senior Member > > Post-Doctoral Fellow > School of Electrical and Computer Engineering > > > University of Campinas, Campinas, SP, Brazil > > http://www.dsee.fee.unicamp.br/ > > Albert Einstein, 400 > 13083-852, Campinas, SP, Brazil > > > -- Dr.-Ing. Santiago Torres IEEE Senior Member Post-Doctoral Fellow School of Electrical and Computer Engineering University of Campinas, Campinas, SP, Brazil http://www.dsee.fee.unicamp.br/ Albert Einstein, 400 13083-852, Campinas, SP, Brazil
