It is correct that in the current MATPOWER OPF, the TAP and SHIFT parameters are fixed input parameters, not variables. I don't think there is a way to fake it with the AC OPF. That is, I think you really need to include them as variables in the flow equations and corresponding derivatives. There may be a way to fake it with dummy injections in the DC OPF, but I haven't really thought about it carefully.
Please let us know if you come up with something that works. And of course, others can feel free to suggest ideas. -- Ray Zimmerman Senior Research Associate 419A Warren Hall, Cornell University, Ithaca, NY 14853 phone: (607) 255-9645 On Apr 16, 2013, at 9:04 AM, Tao HUANG <[email protected]> wrote: > Dear Dr. Ray, > > Speaking of the modeling transformer and phase shifter, I would like to see > if the adjustment of the two parameters (tap ratios and shift angles) along > with the generators and loads could get better results of OPF in terms of > cost and convergence (due to the line limits in some cases). do you have any > suggestions as to how to make the tap ratios and shift angles as variables in > the OPF without using iterative calculation (like blindly or using some > heuristic algorithms to modify them and redo the OPF)? If I understand it > correctly, these two values are fixed before the PF & OPF calculation in > terms of Y matrix at present in Matpower. > > I was considering to model the transformer/ phase shifter as two generators > in respect to the flow limits, but it may split the network into two islands > in some cases. So, do you have any suggestion on this as well? I guess it > also applies to the DC line when it is the only connection between two parts > of the network. > > Thanks a lot > > Best wishes, > > Tao > > From: [email protected] > [mailto:[email protected]] On Behalf Of Ray Zimmerman > Sent: Tuesday, April 16, 2013 2:31 PM > To: MATPOWER discussion forum > Subject: Re: Modelling transformer and phase shifter > > Yes, for a transformer you will typically have an off-nominal taps ratio, > i.e. branch(b, TAP) ~= 1 (or 0, which signifies a normal transmission line). > Similarly, if you have a phase shift, you will have branch(b, SHIFT) ~= 0. > > How the transformer TAP and SHIFT parameters affect the amount of load able > to be dispatched depends on the network, so it could go either way. > > -- > Ray Zimmerman > Senior Research Associate > 419A Warren Hall, Cornell University, Ithaca, NY 14853 > phone: (607) 255-9645 > > > > > > On Apr 16, 2013, at 8:18 AM, Jiashen Teh <[email protected]> > wrote: > > > Dear Dr Ray, > > According to your manual , in section '3.2 Branches' > it is mentioned that: > > 'All transmission lines, transformers and phase shifters are modeled with a > common branch model......' > > Does this mean, if I want to include modelling of transformer at a branch, I > would set the column 9 and 10 of mpc.branch which govern the transformer turn > ratio, N ? > > I notice that for values other than zero for both columns (in a manner to > increase N or reduce N), the network (6 bus) will encounter increase of load > not able to be dispatched. Isn't is load dispatch-able should increase? > > Yours sincerely, > > Jiashen Teh > >
