Dear Mr. Zimmerman, Thank you for your reply. You certainly helped me a lot and clearify some things that were a little bit "fuzzy" to me.
However, I still have one question. The transformer uses the nominal voltages that I introduced in the "node" part of the casefile, right? Does this means that for my case, where V2nominal <> V2rated (110 kV <> 121 kV), I should write in the "node" part for node 2 V2rated instead of V2nominal as the basekV value? Am I right or not in my judgement? Thank you again for your patience and answers, Petre 2012/7/20, Ray Zimmerman <[email protected]>: > 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 >> > > -- Petre Razusi As. drd. ing. Universitatea Politehnica Bucuresti Facultatea de Energetica Departamentul Sisteme Electroenergetice
