You need a row of A for each generator, each one with QPratio in the column corresponding to Pg(i) and -1 in the column corresponding to Qg(i) ...
mpc.A = sparse([1:ng; 1:ng], [2*nb+(1:ng); 2*nb+ng+(1:ng)], [QPratio*ones(ng,1); -ones(ng,1)], 1:ng, 2*nb+2*ng); As I said, this is likely to make the OPF infeasible, so I'm not sure why you'd want to do it. -- Ray Zimmerman Senior Research Associate 211 Warren Hall, Cornell University, Ithaca, NY 14853 phone: (607) 255-9645 On Mar 14, 2011, at 11:17 AM, Roberto Carvalini wrote: > Thank you very much. > > Is it possible for you to give an example, for example case9, for all > generators? I will be appreciate if you do it. > > Best Regards > > R. Carvalini > > On Mon, Mar 14, 2011 at 16:08, Ray Zimmerman <[email protected]> wrote: > The A matrix is from equation (5.25) in the User's Manual. As I mentioned, > the coefficients need to go in the columns corresponding to Pg(1) and Qg(1). > So, Pg(1) is in the first column following the voltage angles (1st nb > columns) and magnitudes (next nb columns), so it's in column 2*nb+1. For > Qg(1) it's the first column after the Pg columns, so 2*nb (for the voltage > angles and magnitudes) plus ng columns for Pg. > > Yes, if you wanted to do this for all generators, you need to include a row > in A for each. Be careful though, this will likely over-constrain the problem > and make it infeasible. If all generators have a fixed power factor, then > balancing the real power output to match the load will mean a specific > reactive power output as well, which will not necessarily match the reactive > power load. > > -- > Ray Zimmerman > Senior Research Associate > 211 Warren Hall, Cornell University, Ithaca, NY 14853 > phone: (607) 255-9645 > > > > On Mar 11, 2011, at 11:40 AM, Roberto Carvalini wrote: > >> Thank you very much. >> >> I have read the manual but I didn't understand by which formula you computed >> this matrix (highlighted) >> >> mpc.A = sparse([1; 1], [2*nb+1; 2*nb+ng+1], [QPratio; -1], 1, 2*nb+2*ng); >> >> and if want to define the same PF for all generators, must I repeat this for >> all or it depends on the type buses (PV or Slack)? >> >> Regards >> >> R. Carvalini >> >> On Fri, Mar 11, 2011 at 16:27, Ray Zimmerman <[email protected]> wrote: >> Dirk's suggestion is fine for a simple power flow. But if you want to run an >> OPF, where the generator dispatch is to be determined by the optimization, >> but subject to a constant power factor constraint, then you will need to >> supply an additional user-defined linear constraint. For example, if you >> want to run case9 with a constant power factor constraint of 0.95 on the >> first generator, you could do it like this ... >> >> define_constants; >> mpc = loadcase('case9'); >> nb = size(mpc.bus, 1); >> ng = size(mpc.gen, 1); >> pf = 0.95; >> QPratio = sqrt(1/pf^2 -1); >> %% add constraint that QPratio * Pg(1) - Qg(1) = 0 >> mpc.A = sparse([1; 1], [2*nb+1; 2*nb+ng+1], [QPratio; -1], 1, 2*nb+2*ng); >> mpc.l = 0; >> mpc.u = 0; >> r = runopf(mpc); >> resulting_pf = r.gen(1, PG) / sqrt(r.gen(1, PG)^2 + r.gen(1, QG)^2) >> >> The important part here is defining the A matrix properly, where the columns >> correspond to voltage angles, voltage magnitudes, generator real injections, >> and generator reactive injections (2*nb + 2*ng columns in all). So the >> coefficients for our constraint co in the columns corresponding to Pg(1) and >> Qg(1). >> >> -- >> Ray Zimmerman >> Senior Research Associate >> 211 Warren Hall, Cornell University, Ithaca, NY 14853 >> phone: (607) 255-9645 >> >> >> >> On Mar 11, 2011, at 9:50 AM, Dirk Van Hertem wrote: >> >>> You model your generator as a load, so it is not represented in your gen >>> matrix. Of course, if you want model your generator in a unit commitment, >>> this may not be trivial... >>> >>> Dirk >>> >>> On 03/11/2011 12:32 PM, Roberto Carvalini wrote: >>>> >>>> Thank you >>>> >>>> How can I add? my problem is this >>>> >>>> Best Wishes >>>> >>>> Roberto >>>> >>>> >>>> On Fri, Mar 11, 2011 at 12:22, Dirk Van Hertem <[email protected]> >>>> wrote: >>>> You can just define them as a PQ bus with negative power... (negative load) >>>> >>>> Dirk >>>> >>>> >>>> On 03/11/2011 12:11 PM, Roberto Carvalini wrote: >>>> Hi >>>> >>>> How can I define constant power factor in MAPOWER for example, for >>>> generators PF=0.9? >>>> >>>> Please help me >>>> >>>> Regards >>>> >>>> Roberto >>>> >>>> >>>> >>>> >>>> -- >>>> Dirk Van Hertem [email protected] >>>> Electrical Engineering Department http://www.esat.kuleuven.be/electa >>>> K.U. Leuven, ESAT-ELECTA GSM: +32-(O)498-61.74.98 >>>> 10, Kasteelpark Arenberg, B-3001 Heverlee fax: +32-16-32.19.85 >>>> >>>> >>>> >>> >>> >>> -- >>> Dirk Van Hertem [email protected] >>> Electrical Engineering Department http://www.esat.kuleuven.be/electa >>> K.U. Leuven, ESAT-ELECTA GSM: +32-(O)498-61.74.98 >>> 10, Kasteelpark Arenberg, B-3001 Heverlee fax: +32-16-32.19.85 >> >> >> >> >> > > > > >
