Hi Xian, It is true that makePTDF() <http://www.pserc.cornell.edu/matpower/docs/ref/matpower6.0/makePTDF.html> is not suitable for large systems, since it does compute sensitivities of flows in all branches with respect to injections at all buses. For a large system, if you want to compute the sensitivities of flows to a particular transfer (e.g. between bus k and the slack), you can do it by solving …
B_dc * ∆x = ∆P_dc … for ∆x, based on eq (4.7) in the User’s Manual, where ∆P_dc is constructed according to the desired transfer. Then compute the corresponding ∆P_f from (3.29). You can use makeBdc() <http://www.pserc.cornell.edu/matpower/docs/ref/matpower6.0/makeBdc.html> to construct B_dc and B_f. If you needed to do this for multiple transfers, you could factor B_dc once beforehand and use the factors to efficiently solve for each ∆x. The option to compute these sensitivities this way would be a nice addition to makePTDF() <http://www.pserc.cornell.edu/matpower/docs/ref/matpower6.0/makePTDF.html> and I would be happy to include such a patch if anyone has the time to create it (see the MATPOWER Contributor’s Guide <https://github.com/MATPOWER/matpower/blob/master/CONTRIBUTING.md>). Feel free to add this to the issue tracker <https://github.com/MATPOWER/matpower/issues> as an enhancement request (and reference this e-mail) if you don’t have to do it yourself, so maybe someone else will take it on. Hope this helps, Ray > On Jan 31, 2017, at 1:46 AM, 郭贤 <[email protected]> wrote: > > Dear all, > > The "make PTDF" is to calculate sensitivity factors for all the buses, since > I have big system with around 20000 buses, when I try to use "make PTDF" > function, the MATLAB program got stuck. Since I did not need PTDF for all > buses, I'm wondering how could I have PTDF for partial buses without > calculating PTDF for all the buses? > > > Thanks a lot. I really appreciate it. > > -- > ————————— > Thanks & Regards > Xian Guo > Iowa State University > Research Assistant in Electric Power and Energy System > ECpE > 1207 Coover Hall
