Thank you for your response. I think I was already using quadratic cost function because in the generator cost data format, I used polynomial cost function with order 2. I do not know if this is what you mean or something else.
----- Original Message ----- From: Ray Zimmerman <[email protected]> Date: Thursday, September 19, 2013 1:32 pm Subject: Re: Question about locational marginal prices To: MATPOWER discussion forum <[email protected]> Cc: [email protected] > First, it is not necessary to switch to AC OPF to get the LMPs to change > continuously with load … simply using quadratic generator costs will do that. > > Regarding the error, I think the error message "either Qmin or Qmax must be > equal to zero for each dispatchable load" is pretty self-explanatory. Your > data must include a dispatchable load that has both QMIN and QMAX non-zero. > This is not allowed. It is assumed that a dispatchable load maintains a > constant power factor, so if QG is negative, then you must specify QMAX = 0 > and QG/PG must equal QMIN/PMIN. If QG is positive, then QMIN = 0 and QG/PG > must equal QMAX/PMIN. > > -- > Ray Zimmerman > Senior Research Associate > B30 Warren Hall, Cornell University, Ithaca, NY 14853 > phone: (607) 255-9645 > > > > > > On Sep 19, 2013, at 11:27 AM, Haneen Mohammad dawoud Aburub > <[email protected]> wrote: > > Thank you so much for your help. Now I understood why LMPs are not changing > on the same bus with change in load, and because of that I replaced > (rundcopf) by (runopf) to perform ACOPF. Also, I changed (OPF_ALG_DC) to > (OPF_ALG), but I got the following error: > > ??? Error using ==> makeAvl at 73 > makeAvl: either Qmin or Qmax must be equal to zero for each dispatchable load. > Error in ==> opf_setup at 172 > [Avl, lvl, uvl] = makeAvl(baseMVA, gen); > Error in ==> opf at 219 > om = opf_setup(mpc, mpopt); > Error in ==> runopf at 96 > [r, success] = opf(casedata, mpopt); > Error in ==> run_3bus at 120 > results = runopf(mpc, opt); > What this error means? What should I do else to have a correct ACOPF? > > Thanks again, appreciate your help. > > ----- Original Message ----- > From: Ray Bo <[email protected]> > Date: Monday, September 16, 2013 11:04 pm > Subject: Re: Question about locational marginal prices > To: MATPOWER discussion forum <[email protected]> > > > > > It could very well be the case when transmission losses are not considered > > and piecewise linear cost function is assumed for generators. LMPs will > > stay the same until there is a change in the marginal units and/or change > > in congested lines when load grows beyond certain level. The following two > > papers might help understand that. > > https://sites.google.com/site/eeruibo/files/DCOPF_LMP.pdf?attredirects=0 > > https://sites.google.com/site/eeruibo/files/congestion_and_LMP_prediction.pdf?attredirects=0 > > > > -Rui > > > > Rui (Ray) Bo > > Ph.D., SM-IEEE > > Senior Economic Studies Engineer > > Policy & Economic Studies > > MISO > > Phone: (651) 632-8447 > > Email: [email protected], [email protected] > > > > > > From: Haneen Mohammad dawoud Aburub > > Sent: Monday, September 16, 2013 12:24 > > To: [email protected] > > Subject: Question about locational marginal prices > > > > Hi, > > > > I used the DCOPF to get the locational marginal prices of a 3-bust system. > > The locational marginal prices that I have got are not changing with the > > change in load. Can you please tell me the reason of that. > > > > Thank you. >
