Yes, although the default value of 0 (meaning no tap switching capability) actually means a 1.0 tap, that is, a nominal ratio.
carlos. On Wed, Aug 29, 2012 at 2:26 PM, Cansu Yildirim <[email protected]> wrote: > 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 >>> >>> >> > >
