Alright, thanks a lot once again! Now I should be able to model tap transformers as well!
Regards, Cansu On 29.08.2012, at 20:30, "Carlos Murillo" <[email protected]> wrote: > 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 >>>> >>>> >>> >> >> >
