The PTDF shows how the power flows change based on load changes, given a specific slack distribution. When you say that it "works for DC PF", I assume you mean that you can use it to predict the new flows you get when you run a new DC PF. That's because you probably are using the same slack bus for both. If you think about how a DC OPF redispatches for an incremental load change, the "slack" is taken up by the units that are on the margin. I'm not sure how to compute what the proportion is, but if you knew that proportion you could use it to specify the slack distribution for computing the appropriate PTDF.
-- Ray Zimmerman Senior Research Associate 211 Warren Hall, Cornell University, Ithaca, NY 14853 phone: (607) 255-9645 On Mar 2, 2011, at 5:27 PM, z qin wrote: > Hello, > > It seems that the linear shift factors (PTDF matrix) only works for DC PF, > but not for DC OPF. Is there a corresponding matrix for DC OPF? I am > wondering how the power flows on all the branches change if one bus's power > demand changes. Any suggestions? Thanks a lot. > > Jerry
