Hello Houssem, I don't know the reason why line Q-losses are reported that way in MATPOWER, but heuristically, if voltages are kept within reasonable bounds (say 0.9 to 1.10 in pu) then you can see that Q injections from line Bshunts will remain also bounded, as they are equal to Bs·V^2. By contrast, the transmission part of Q-losses (I^2·X) can vary orders of magnitude, depending on the load on the transmission network.
-- Jose L. Marin Grupo AIA On Mon, Apr 4, 2016 at 3:22 AM, Houssem <bouchekara.hous...@gmail.com> wrote: > > Thanks Gang for your answer. This confirms my thoughts because it is > written I^2*Z above losses. Therefore, these losses are power loss in the > series portion of the pi-model of the transmission line. > However, in an OPF problem where the objective is to minimize reactive > power transmission losses, reactive losses are computed taking into account > both portions of the transmission line (i.e. line charging capacitance > portions of the pi-model are also included). So what is the goal of > calculating losses in matpower including only the series portion? Is there > any advantages of doing so? > > Regards > > Houssem > > > > On 03/04/2016 11:59 PM, Gang Huang wrote: > > Dear Houssem, > > > > Please note that transmission lines have charging susceptance (i.e., > mpc.branch(:, BR_B)), and its contribution to the reactive power is not > listed in the pretty-printed output. > > > > Best regards, > > > > Gang > > > > *From:* bounce-120330262-73377...@list.cornell.edu [ > mailto:bounce-120330262-73377...@list.cornell.edu > <bounce-120330262-73377...@list.cornell.edu>] *On Behalf Of *Houssem > *Sent:* Sunday, April 03, 2016 11:29 AM > *To:* MATPOWER discussion forum > *Subject:* question about losses > > > > Dear All > I have a small question about losses in matpower . > I have run a small program with 3 buses in matpower 4.1. > The obtained results are: > > ================================================================================ > | Branch > Data | > > ================================================================================ > Brnch From To From Bus Injection To Bus Injection Loss (I^2 * > Z) > # Bus Bus P (MW) Q (MVAr) P (MW) Q (MVAr) P (MW) Q > (MVAr) > ----- ----- ----- -------- -------- -------- -------- -------- > -------- > 1 1 2 179.33 116.79 -170.96 > -102.71 8.369 16.74 > *2 1 3 39.03 20.69 -38.85 > -22.98 0.183 0.55* > 3 2 3 -229.04 -147.29 238.85 166.92 > 9.813 19.63 > -------- > -------- > Total: 18.365 > 36.91 > > my question is, in line 2 Qlosses should be (20.69)+(-22.98) =-2.29 MVar. > However matpower displays 0.55MVar !!! is there any explanation to that? > same for branch 1. > Regards > Houssem > > >
