sparse is a built-in Matlab function, see the Matlab documentation for more details. MATPOWER really does assume a basic knowledge of Matlab and there are other forums for asking Matlab questions. So please make sure you understand all of the Matlab commands involved before posting questions here about MATPOWER.
The A matrix is from equation (5.25) in the User's Manual, where x is defined in (5.5). So as it says in the example code I provided you, the constraint we want to implement is ... 0 <= QPratio * Pg(i) - Qg(i) <= 0 This is an equality constraint that forces a constant ratio between Qg(i) and Pg(i), in other words, a constant power factor. So we need to define A such that A * x = QPratio * Pg(i) - Qg(i), which means that A needs to have QPratio in the column corresponding to Pg(i) and -1 in the column corresponding to Qg(i). If you look at equation (5.5), you'll see that Pg(i) is found in element (2*nb + i) of x and Qg(i) in element (2*nb+ng+i). The sparse statement constructs this A matrix, and l and u from (5.25) are set to zero. Hope this finally makes everything clear. -- Ray Zimmerman Senior Research Associate 211 Warren Hall, Cornell University, Ithaca, NY 14853 phone: (607) 255-9645 On Mar 15, 2011, at 10:46 AM, Carlos Gonzalez Almeida wrote: > Thank you very much dear Prof. Zimmerman > > My problem is that I don't understand the sparse() function used to construct > the A matrix especially don't understand how the A matrix defined in the > example implements a constant power factor constraint. The latter is very > important for me. I will be greatly appreciated you if you explain me further. > > Best Regards > > Carlos > > On Tue, Mar 15, 2011 at 15:41, Ray Zimmerman <[email protected]> wrote: > In order to help you further, you're going to have to be more specific about > what it is that you are having trouble with. Is it that you don't understand > the sparse() function used to construct the A matrix? Or that you don't > understand how the A matrix is used? Or you don't understand how the A matrix > defined in the example implements a constant power factor constraint? > > Btw, if anyone else on the list can see something I'm missing in my attempts > to help Carlos get up to speed ... jump in, don't be shy. > > -- > Ray Zimmerman > Senior Research Associate > 211 Warren Hall, Cornell University, Ithaca, NY 14853 > phone: (607) 255-9645 > > > > On Mar 15, 2011, at 9:31 AM, Carlos Gonzalez Almeida wrote: > >> Dear Prof. Zimmerman >> >> Once again I appreciate you for the file that you sent me. Where can I find >> more information about the way of definition of A matrix. I have read the >> manual but I didn't understand well, for example in the case you sent me >> yesterday. If it is possible either please introduce me a book or explain a >> little bit more about A matrix in general. >> >> Best Wishes >> >> C. Gonzalez Almeida >> >> >> On Mon, Mar 14, 2011 at 19:05, Carlos Gonzalez Almeida >> <[email protected]> wrote: >> Thank you very very much. >> >> On Mon, Mar 14, 2011 at 18:59, Ray Zimmerman <[email protected]> wrote: >> Did you understand the previous example? If so, it's a trivial modification >> (attached). If not, please go back and familiarize yourself with the >> extended OPF formulation in the manual, the paper, the slides for the paper, >> etc. This is about the most trivial example can think of for adding a >> user-defined constraint to the OPF. >> >> >> >> -- >> Ray Zimmerman >> Senior Research Associate >> 211 Warren Hall, Cornell University, Ithaca, NY 14853 >> phone: (607) 255-9645 >> >> >> >> On Mar 14, 2011, at 12:16 PM, Carlos Gonzalez Almeida wrote: >> >>> With more details I want to do runmarket and I want to have PF=0.85 for >>> example in case9 for generators 2, 3. How can I do it? >>> >>> Best Wishes >>> >>> C. Gonzalez Almeida >>> >>> >>> On Mon, Mar 14, 2011 at 17:10, Carlos Gonzalez Almeida >>> <[email protected]> wrote: >>> Thank you. >>> >>> I also have the Roberto's problem as well as in the case of runmarket to >>> set an specified power factor for generators except slack bus. >>> >>> If it is possible please give an example. Because it can be useful for >>> other people who will use in the future MATPOWER. >>> >>> Best Wishes >>> >>> C. Gonzalez Almeida >>> >>> >>> On Mon, Mar 14, 2011 at 16:59, Ray Zimmerman <[email protected]> wrote: >>> 1. You can constrain a generator to have a zero power factor by setting >>> PMIN = PMAX = 1. The generator reactive power is one of the optimization >>> variables in x, so it's value is determined by whatever solver you happen >>> to be using, MIPS by default. So I suppose if you need to know which m-file >>> computes its value, it would be mips.m. If you want to set the reactive >>> power of generator 2 to zero, simply set both the QMIN and QMAX column in >>> the corresponding row of the gen matrix to zero (by the way, that is a >>> power factor of 1, not 0). >>> >>> Without more details I have no idea. Are you passing in any reactive power >>> offers? >>> >>> -- >>> Ray Zimmerman >>> Senior Research Associate >>> 211 Warren Hall, Cornell University, Ithaca, NY 14853 >>> phone: (607) 255-9645 >>> >>> >>> >>> On Mar 14, 2011, at 6:17 AM, Carlos Gonzalez Almeida wrote: >>> >>>> Dear Prof. Zimmerman >>>> >>>> 1.I studied the your response to Roberto Carvalini but I don't know how >>>> can I define the PF for other generators to zero or other values when I do >>>> runmarket and it doesn't work the code when I do runmarket. By which >>>> formula you have computed the generator reactive power (in which m.file, >>>> please address the m.file because I couldn't find it). For example, if I >>>> want to set reactive power of generator 2 to zero, what should I do? >>>> >>>> 2. Why I cannot do runmarket for case30Q and case9Q? what is the reason? >>>> >>>> >>>> Best Wishes >>>> >>>> C. Gonzalez Almeida >>>> >>>> >>>> On Fri, Mar 11, 2011 at 16:29, Ray Zimmerman <[email protected]> wrote: >>>> See my response to Roberto Carvalini, posted only seconds ago. Am I fast >>>> or what? ;-) >>>> >>>> -- >>>> Ray Zimmerman >>>> Senior Research Associate >>>> 211 Warren Hall, Cornell University, Ithaca, NY 14853 >>>> phone: (607) 255-9645 >>>> >>>> >>>> >>>> On Mar 11, 2011, at 10:16 AM, Carlos Gonzalez Almeida wrote: >>>> >>>>> Thank you very much. >>>>> >>>>> Could you please give me an example about defining power factor for >>>>> generators? >>>>> >>>>> I cannot set it. >>>>> >>>>> On Fri, Mar 11, 2011 at 16:09, Ray Zimmerman <[email protected]> wrote: >>>>> Carlos, >>>>> >>>>> If you want the loads to have a power factor of 0.95, you need to set QD >>>>> such that PD/sqrt(PD^2 + QD^2) = 0.95, i.e. QD has to equal 0.108 * PD. >>>>> About the voltage constraint of 1.5 p.u., I don't see that anywhere, so >>>>> I'm not sure what you are referring to. The different lambdas at the two >>>>> buses are due to losses. The power factor of the generators is determined >>>>> by the solution algorithm within the bounds set for them. That is, each >>>>> generator has a feasible "box" defined by PMIN, PMAX, QMIN and QMAX. You >>>>> don't normally "set" the power factor of a generator as input to the OPF. >>>>> I suppose, if for some reason you have a strict power factor constraint >>>>> on a generator you could use some additional linear constraints to the >>>>> OPF to enforce it, but that would be unusual I think. >>>>> >>>>> -- >>>>> Ray Zimmerman >>>>> Senior Research Associate >>>>> 211 Warren Hall, Cornell University, Ithaca, NY 14853 >>>>> phone: (607) 255-9645 >>>>> >>>>> >>>>> >>>>> On Mar 10, 2011, at 8:10 AM, Carlos Gonzalez Almeida wrote: >>>>> >>>>>> Another question is this: when I have not fixed loads only I have >>>>>> dispatchable loads how can I define power factor for generators and >>>>>> loads separately? >>>>>> >>>>>> Best Wishes >>>>>> >>>>>> Carlos >>>>>> >>>>>> On Thu, Mar 10, 2011 at 13:53, Carlos Gonzalez Almeida >>>>>> <[email protected]> wrote: >>>>>> Dear Prof. Zimmerman >>>>>> >>>>>> Thanks a lot for your useful guidance. >>>>>> >>>>>> For example, in the attached file for a simple case study with 2 loads >>>>>> and generators I want to have a power factor 0.95. I have problem with >>>>>> adjusting power factor in MATPOWER. How can I do it in the attached >>>>>> file? Also I don't know why I have voltage constraint 1.5 pu. I think >>>>>> because of these constraints I have a little bit difference in the value >>>>>> of lambda >>>>>> I have done runmarket with the following offers and bids. >>>>>> Could you please tell me why? >>>>>> >>>>>> +++++++++++++++++++++ >>>>>> mpc0 = loadcase('case4gs1'); >>>>>> mpc = load2disp(mpc0); >>>>>> mkt.OPF = 'AC'; >>>>>> offers.P.qty = [100;70]; >>>>>> offers.P.prc = [50;100]; >>>>>> bids.P.qty = [50 ;70 ]; >>>>>> bids.P.prc = [150 ;130 ]; >>>>>> [r, co, cb] = runmarket(mpc, offers, bids, mkt); >>>>>> co.P.qty >>>>>> co.P.prc >>>>>> cb.P.qty >>>>>> cb.P.prc >>>>>> ++++++++++++++++++++++++ >>>>>> >>>>>> Best Wishes >>>>>> >>>>>> C. Gonzalez Almeida >>>>>> >>>>>> >>>>>> >>>>>> On Wed, Mar 9, 2011 at 19:47, Ray Zimmerman <[email protected]> wrote: >>>>>> Carlos, >>>>>> >>>>>> I'm not sure what you mean by "test the example ... regarding zero power >>>>>> factor". If you are going to change some of the existing dispatchable >>>>>> loads to have a zero power factor, then the existing market structure >>>>>> for the example, which includes only $/MW bids for active power, will >>>>>> not be applicable. So you need to decide how you want to handle these >>>>>> reactive-only loads. I suppose you'll need to specify reactive power >>>>>> bids for them. >>>>>> >>>>>> On your second question, the offers and bids are used to construct a >>>>>> gencost matrix with negative costs for the negative generators that >>>>>> represent dispatchable loads. The objective function is then to minimize >>>>>> this "cost" of generation, which is computed in opf_costfcn.m. You are >>>>>> correct that this is equivalent to maximizing social welfare. >>>>>> >>>>>> -- >>>>>> Ray Zimmerman >>>>>> Senior Research Associate >>>>>> 211 Warren Hall, Cornell University, Ithaca, NY 14853 >>>>>> phone: (607) 255-9645 >>>>>> >>>>>> >>>>>> >>>>>> On Mar 8, 2011, at 5:04 PM, Carlos Gonzalez Almeida wrote: >>>>>> >>>>>>> Dear Dr. Zimmerman >>>>>>> >>>>>>> -Could you please test the example provided in the manual >>>>>>> (t_auction_case) regarding zero power factor. What changes should be >>>>>>> carried out? >>>>>>> >>>>>>> -Moreover, as you know, the objective function obtained in the >>>>>>> runmarket is Social welfare. Could you please address me the file that >>>>>>> you calculated objective function because I couldn't find it. I want >>>>>>> to know in which file (the m file) you have calculated that? >>>>>>> >>>>>>> Best Regards >>>>>>> >>>>>>> Carlos >>>>>>> >>>>>>> >>>>>>> >>>>>>> On Tue, Mar 8, 2011 at 22:34, Ray Zimmerman <[email protected]> wrote: >>>>>>> I'm not really sure without seeing the details of your example. I'm not >>>>>>> sure I've ever tested the runmarket code with pure reactive power >>>>>>> loads. It would require reactive power bids for those loads, but I'll >>>>>>> need the details to be able to help you further. >>>>>>> >>>>>>> -- >>>>>>> Ray Zimmerman >>>>>>> Senior Research Associate >>>>>>> 211 Warren Hall, Cornell University, Ithaca, NY 14853 >>>>>>> phone: (607) 255-9645 >>>>>>> >>>>>>> >>>>>>> >>>>>>> On Mar 7, 2011, at 10:42 AM, Carlos Gonzalez Almeida wrote: >>>>>>> >>>>>>>> Hi >>>>>>>> >>>>>>>> I am new in MATPOWER abd I want to have zero power factor for example >>>>>>>> in example case of manual in runmarket, but several error are occured. >>>>>>>> please tell me why >>>>>>>> >>>>>>>> >>>>>>>> Best Wishes >>>>>>>> >>>>>>>> C. Gonzalez Almeida >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> Best Wishes >>>>>>> >>>>>>> C. Gonzalez Almeida >>>>>> >>>>>> >>>>>> >>>>>> >>>>> >>>>> >>>>> >>>>> >>>>> Best Wishes >>>>> >>>>> C. Gonzalez Almeida >>>> >>>> >>>> >>> >>> >>> >> >> >> >> >> >> Best Wishes >> >> C. Gonzalez Almeida >> > > > > > Best Wishes > > C. Gonzalez Almeida
