Thank you very much for your quick answer Carlos! So in my case, since I have just a normal transformer, this would mean that the tap parameter is zero right?
Regards, Cansu On 29.08.2012, at 19:57, "Carlos Murillo" <[email protected]> wrote: > Matpower uses the one line network representation in the per unit > system. One of the main ideas behind the per unit system is to get rid > of all the transformers and instead represent all voltages normalized > to the nominal voltage of the branch/bus in question. Variable tap > transformers are special transformers that can be tapped at points off > the nominal ratio. That is what the tap parameter represents; it does > not represent the turns ratio of the transformer. Please refer to any > textbook on power systems to see how the per unit system is employed. > > carlos. > > On Wed, Aug 29, 2012 at 1:09 PM, Cansu Yildirim <[email protected]> wrote: >> Hello, >> >> I'm currently trying to get familiar with matpower. I have following problem >> with the 'transformer off nominal ratio'. >> >> I need to model a transformer. The values given are following one: >> >> U1: 20 kV >> U2: 0.4 kV >> rated power: 400 kVA >> no load losses: 0.61 >> no load current (%): 0.1525 >> u_k: 3.85 >> Cu losses: 4.6 kW >> switching group: Dy5 >> >> I have following questions: >> >> 1) how do I calculate the TAP? When I look into the casefiles, I can see >> that the value fpr the tap is most time between 0.8 and 1.5 >> I would have calculated by dividing 20kV/0.4KV=25 which does not seem >> to be the correct value for the tap. >> >> 2) How do I identify the BR_X and BR_B ? When I look into the equivalent >> circuit diagram I know that there are more components that need to be >> calculated. So what >> do these parameters mean for the transformer? >> >> I would be grateful for any help. >> >> >> Kind regards, >> >> >> Cansu Yildirim >> >> >
