Well … QPratio * Pg(i) - Qg(i) is not the power factor. So limiting it to a range ...
-0.95 <= QPratio * Pg(i) - Qg(i) <= 0.95 … does *not* limit power factor to that range. You want a linear constraint on Pg and Qg that is equivalent to abs(pf) <= 0.95. Just plug in the correct definition of power factor in terms of Pg and Qg and do some algebra to get the correct constraints. -- Ray Zimmerman Senior Research Associate B30 Warren Hall, Cornell University, Ithaca, NY 14853 phone: (607) 255-9645 On Jan 10, 2014, at 4:34 AM, Dailan Xu <[email protected]> wrote: > Dear Dr. Zimmerman, > > Thank you. It gives the same results as before. Nothing is changed. I want to > replace zero "0" in upper and lower limits with -0.95 and 0.95 (-0.95 <= > QPratio * Pg(i) - Qg(i) <= 0.95). I know what is power factor. If possible, > please help me. I will be very grateful. > > > In previous post you explained it as follow: > > "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." > > Best regards, > >
