I want to have power factor in a certain range, for instance varying between 0.9 leading and 0.9 lagging.
Best regards On Thu, Jan 9, 2014 at 3:05 PM, Ray Zimmerman <[email protected]> wrote: > First step: What is the constraint you want to implement, expressed in > terms of Pg and Qg? > > -- > Ray Zimmerman > Senior Research Associate > B30 Warren Hall, Cornell University, Ithaca, NY 14853 > phone: (607) 255-9645 > > > > On Jan 9, 2014, at 9:34 AM, Dailan Xu <[email protected]> wrote: > > I tried the following code but the results are the same compared to > previous one. > > > nb = size(mpc.bus, 1); > ng = size(mpc.gen, 1); > pf = 0.8; > QPratio = sqrt(1/pf^2 -1); > %% add constraint that QPratio * Pg(i) - Qg(i) = 0, for i = 2 .. ng > mpc.A = sparse([1:ng 1:ng]', [2*nb+(1:ng) 2*nb+ng+(1:ng)]', > [QPratio*ones(ng,1); -ones(ng,1)], ng, 2*nb+2*ng); > % mpc.A = mpc.A(3:12, :); > % mpc.l = zeros(ng-1-31, 1); > mpc.A = mpc.A(2:16, :); > mpc.l = -0.8*ones(ng-29-1, 1); > mpc.u = -mpc.l; > > Best regards, > > > > I found one of your posts below but I don't know how can I implement > A,l,u. > > ---------- Forwarded message ---------- > From: Ray Zimmerman <[email protected]> > Date: Wed, Mar 16, 2011 at 3:36 PM > Subject: Re: PF > To: MATPOWER discussion forum <[email protected]> > > > 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 > > > > > >
