That is correct. As described in caseformat and Table B-3 in the manual, the tap ratio is such that, in the case where r = x = b = 0, it is equal to the "from bus voltage (in p.u.) divided by the “to” bus voltage (in p.u.), Vf/Vt. So, in your case this is V1/V2, where V1 is 1.0 p.u. and V2 is 13.14/13.8 = 0.95217 p.u., so tap is 13.8/13.14 as you stated.
Ray On Jan 3, 2021, at 8:06 PM, Russ Patterson <[email protected]<mailto:[email protected]>> wrote: Hi Ray, In the branch data for the #2 transformer (the one that is on 161:13.14kV tap) what should TAP be? Bank #1 ratio matches the ratio of bus voltage bases (161/13.8) so its ratio is set to 1.0 So, I think the #2 transformer TAP (ratio ) should be (13.8/13.14 = 1.0502). Is that correct? <image001.png> <image002.png> Best regards, Russ From: [email protected]<mailto:[email protected]> [mailto:[email protected]] On Behalf Of Ray Daniel Zimmerman Sent: Monday, December 21, 2020 11:44 AM To: MATPOWER-L Subject: Re: circulating current (MVAR loss) I suggest double-checking your calculations against the code in makeYbus.m, which is pretty straightforward, and the model described in the User’s Manual<https://matpower.org/docs/MATPOWER-manual-7.1.pdf> see Figure 3-1 and equation (3.2). Be sure to keep in mind the orientation of the taps in the model. Ray On Dec 16, 2020, at 3:52 PM, Russ Patterson <[email protected]<mailto:[email protected]>> wrote: Carlos – thank you. Very helpful. The YBus I get for my case is below. I expected Y(1,1) to equal the of this sum: (1/j0.1) + (1/j0.09522) + (1/-j1.991) = j 19.9997 (negative sign is per coder preference). Is attached (page 1) not how MATPOWER would modify the bank #2 impedances before creating YBUS? Yb = Compressed Column Sparse (rows = 2, cols = 2, nnz = 4 [100%]) (1, 1) -> 0 - 19.0663i (2, 1) -> 0 + 19.5217i (1, 2) -> 0 + 19.5217i (2, 2) -> 0 - 20i Best regards, russ From: [email protected]<mailto:[email protected]> [mailto:[email protected]] On Behalf Of Carlos E Murillo-Sanchez Sent: Wednesday, December 16, 2020 4:12 PM To: MATPOWER discussion forum Subject: Re: circulating current (MVAR loss) Russ Patterson wrote: Hi - I am still trying to hand calculate the flow into branch 2 from bus 1 to bus 2. I can’t get my results to match MATPOWER. I get Q into the banks from bus 1 of, Bank #1: 24.00 MVAR Bank #2: -25.02 MVAr Attached is my short calculation and the .m file. Is there a way to have MATPOWER barf out the YBUS matrix? >> help makeYbus If buses are numbered consecutively starting from 1 in the bus table (see ext2int if not), simply type: >> mpc = loadcase('mycase'); >> [Yb, Yf, Yt] = makeYbus(mpc) To get all the relevant current injections in the solved case, simply do >> mpc = runpf(mpc); >> define_constants; >> V = mpc.bus(:, VM) .* exp(1i * mpc.bus(:, VA)*pi/180); >> Ibus = Yb * V >> Ifrom = Yf * V; >> Ito = Yt * V; From there, compute power injections as >> Sbusinj = V .* conj(Yb * V); >> Sfrominj = V(mpc.branch(:, F_BUS)) .* conj(Yf * V); >> Stoinj = V(mpc.branch(:, T_BUS)) .* conj(Yt * V); carlos. <power.pdf> <circulating_current_no_load.m><per_gross.pdf>
