The tap ratio parameter is 1 at the nominal voltages, that is, at tap 0. I'm not certain, but I think you'd use a tap ratio of 449.92/400 = 1.1248 for tap +8.
-- Ray Zimmerman Senior Research Associate 419A Warren Hall, Cornell University, Ithaca, NY 14853 phone: (607) 255-9645 On Jul 19, 2012, at 1:41 PM, Petre Razusi wrote: > Hi everyone! > > I need to model a transformer in Matpower and I need help regarding > the calculation of tap ratio. > > My transformer is connected between two nodes, 1 and 2, which have the > following nominal voltages: V1n=400 kV, V2n=110 kV. > The rated voltages for the transformer are: V1r=400 kV, V2r=121 kV. > The transformer has 17 taps (+/-8) with the following voltages for the > maximum and minimum taps: V1 for -8=350.08 kV, V1 for +8=449,92 kV. > > Can anyone tell me what is the "tap ratio" parameter that is needed in > the casefile? I mean, how do you calculate it for tap 0? And how do > you do it for tap +8? > > Thank you all in advance for your help! > Petre >
