I believe both of your questions have the same answer: When you allow more
flexibility in the system (increased range of generator voltages or variable
power factor) there are more degrees of freedom to use to reduce costs. In
particular, there is more flexibility that can be used to minimize losses,
resulting in a decrease in overall generator output.
--
Ray Zimmerman
Senior Research Associate
B30 Warren Hall, Cornell University, Ithaca, NY 14853
phone: (607) 255-9645
On Jan 7, 2014, at 5:59 AM, Carlos Gonzalez Almeida
<cgonzalezalme...@gmail.com> wrote:
> Dear Dr. Zimmerman,
>
> When I am running an OPF considering two cases;
>
> 1) Fixed power factor
> 2) variable power factor
>
> in (1) the total output power of generators are higher than that obtained in
> (2). But It should be vice versa conceptually, i.e. it should be higher in
> case (2). Could you please let me know what is the reason?
>
> The following codes have been used to obtain the results.
>
> (1)
>
> define_constants;
> mpc = loadcase('case9');
> nb = size(mpc.bus, 1);
> ng = size(mpc.gen, 1);
> pf = 0.85;
> 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(2:end, :);
> mpc.l = zeros(ng-1, 1);
> mpc.u = mpc.l;
> r = runopf(mpc);
> **************************************************
>
> (2)
>
> define_constants;
> mpc = loadcase('case9');
> r = runopf(mpc);
> ****************************************
>
> According to abovementioned codes
>
>
> Best regards,
>
