Yes, in the current MATPOWER case format v2, the transformers are specified in the same branch matrix as the AC transmission lines. I’m a bit rusty on my transformer modeling, so someone please correct me if I’m wrong, but I believe the % impedance specification is equivalent to the p.u. impedance value expressed using the transformer rated power and voltages as the per-unit bases. So I think you just have to convert the impedance to the system per-unit bases to put it in the branch matrix.
Ray > On Aug 2, 2021, at 9:49 AM, Jean-Francois Simon <[email protected]> wrote: > > Good day, > > > I am learning MatPower and have a case to study with 8 buses. The below > example a simplification: > > I could understand how to build buses and links and simulate the energy flow. > Results look right, > however I have a question since the buses are working on different voltage > levels, hence some > links have power transformers. > > *** Bus 2: 90 kV - Feeder bus *** > *** Bus 3: 30 kV - Load bus *** > *** Bus 5: 690 V - Load bus *** > > <Bus 2>---(90/30kV XFR)---<Bus 3>---(30/.69 kV XFR)---<Bus 5> > > Bus 2 to bus 3 is a 16 MVA transformer with impedance 10.5% > Bus 3 to bus 5 is a 5 MVA transformer with impedance 6.5% > > At the moment, the bus definition looks like this: > > mpc.bus = [ > 2 3 0.0 0.0 0 0 1 1 0 90.0 1 1.1 0.9; > 3 1 7.2 2.1 0 0 1 1 0 30.0 1 1.1 0.9; > 5 1 3.5 0.1 0 0 1 1 0 0.69 1 1.1 0.9; > ]; > > And branches definition is incomplete: > > mpc.branch = [ > 2 3 0.1 0 0 250 250 250 0 0 1 -360 360; > 3 5 0.1 0 0 250 250 250 0 0 1 -360 360; > ]; > > > Is this right transformers are set in "Branches" ? How do we calculate and > set resistance branches > resistance and and reactance in order to properly integrate transformers as > for example in above > case ? > > > Thank you for support, > > > Regards, > > Jean-François Simon > >
