First of all, the OPF algorithms in MATPOWER are only expected to work reliably on convex cost functions (which you do not have). It turns out that using OPF_ALG_DC = 100 (for BPMPD) does give nearly the same answer for the DC OPF.
-- Ray Zimmerman Senior Research Associate 211 Warren Hall, Cornell University, Ithaca, NY 14853 phone: (607) 255-9645 On May 11, 2011, at 7:42 PM, Santiago Chamba wrote: > Hello all, > > In this moment, I am understanding the mechanism about of the minimization of > cost with curves cost and load benefit. For this reason, I have posed a > problem with generators and dispatchable loads in a two nodes system with the > following equations: > > f1 = 0.05*p(1)^2+100*p(1; in node 1 (generator 1); limits 0<p(1)<100 > f2 = -0.05*p(2)^2+100*p(2); in node 1(dispatchable load 1); limits > -100<p(1)<0 > f3 = -0.06*p(3)^2+120*p(3); in node 2 (generator 2); limits 0<p(1)<100 > f4 = 0.06*p(4)^2+120*p(4) ; in node 2 (dispatchable load 2); limits > -100<p(1)<0 > > With this conditions, I run DC OPF and AC OPF and found the following results > of generation and distpachable load: > > DC OPF AC OPF > generator 1 89.0265 90.8313 > dispatchable load 1 -89.0265 -0.0000 > generator 2 92.4779 0.0000 > dispatchable load 2 92.4779 -90.8238 > > To compare these results, I used the Matlab’s Toolbox, specifically fmimcon, > to optimize these curves and the results are: > > x = > 90.9091 0.0000 -0.0000 -90.9091 > fval = > -909.0909 > > Why are they so different the DC and AC results?. > > PD: The problem is designed to optimized the curves f1 and f4, because the > curves f2 and f3 are the reflecting of the curves f1 and f4 (this case is > only to understand the mechanism). The problem is attached. > > Thanks so much for the help. > > Santiago Ch. > > > <mer.m>
