Hi, thanks for your help. I am not sure if I can follow, though.
1) The formula you have posted implies that the results of the power flow
analysis change if the base voltage is modified.
It seems to me, that this is not the case in Matpower. Changing the
base voltages in "case9.m" from 345 to 200 or some other value
and then executing 'runpf' yields exactly the same results as the
case without modifications does.
2) I tried to adjust the r and x columns of the branch data according to
your formula (kVAnew=100, kVAgiven=1000 ==> Znew (pu)= 0.1 * Zgiven(pu) )
The results of runpf do still differ from the original results
Von: [email protected]
An: "MATPOWER discussion forum" <[email protected]>
Datum: 29.04.2011 14:40
Betreff: Re: Question on baseMVA
Gesendet von: [email protected]
> Hi, I have a question about Matpower 4.0
>
> By running" runpf('case9') " I get the power flow of the 9-bus system.
> If I change baseMVA from 100 to 1000 or 10 in file 'case9.m',
> the results of power flow do change completely! Why?
> Is this because the r, x and b columns are expressed by p.u.-values?
> If so, how do I have to transform them in order to receive the same
> results as before? How do I choose a baseMVA value for an unknown
> System?
> Thanks very much
>
Well,
If you want to change your MVA base and/or voltage base, all the
pu impedances must be changed accordingly by:
Znew(pu) = Zgiven(pu)((KVgiven/kVnew)^2)(kVAnew/kVAgiven)
I hope it helps.
Prof. J.R. Camacho
UFU - School of Electrical Engineering
Uberlandia - MG - Brazil
[email protected]
