If you remove or otherwise modify branch k, from bus i to bus j, then you
should expect changes to elements (k,i) and (k,j) of Yf and Yt, whereas in Ybus
it will be elements (i,i),(i,j),(j,i) and (j,j).
Yf and Yt relate bus voltages to branch flows. Ybus relates bus voltages to bus
injections.
Ray
> On Oct 11, 2017, at 4:47 AM, Ehsan Hejri <[email protected]> wrote:
>
> Dear MATPOWER user,
>
> I want to remove a line (between bus1 and bus2) from a network.
> I put branch status = 0 for that line.
>
> Then I used makeYbus function to calculate Ybus, Yf and Yt.
>
> [Ybus, Yf, Yt] = makeYbus(baseMVA, bus, branch)
>
> In Ybus matrix, Y(1 , 2) and Y(2 , 1) are removed.
>
> Ybus =
>
> (1,1) 1.2500 - 3.7250i
> (3,1) -1.2500 + 3.7500i
> (2,2) 5.8333 -17.4450i
> (3,2) -1.6667 + 5.0000i
> (4,2) -1.6667 + 5.0000i
> (5,2) -2.5000 + 7.5000i
> (1,3) -1.2500 + 3.7500i
> (2,3) -1.6667 + 5.0000i
> (3,3) 12.9167 -38.6950i
> (4,3) -10.0000 +30.0000i
> (2,4) -1.6667 + 5.0000i
> (3,4) -10.0000 +30.0000i
> (4,4) 12.9167 -38.6950i
> (5,4) -1.2500 + 3.7500i
> (2,5) -2.5000 + 7.5000i
> (4,5) -1.2500 + 3.7500i
> (5,5) 3.7500 -11.2100i
>
> But in Yf matrix only Yf(1 , 2) has been removed and Yf(2 , 1) still has a
> value which means if we multiply that to the voltage we have current (From
> bus) in this line.
>
> Yf =
>
> (2,1) 1.2500 - 3.7250i
> (3,2) 1.6667 - 4.9800i
> (4,2) 1.6667 - 4.9800i
> (5,2) 2.5000 - 7.4850i
> (2,3) -1.2500 + 3.7500i
> (3,3) -1.6667 + 5.0000i
> (6,3) 10.0000 -29.9900i
> (4,4) -1.6667 + 5.0000i
> (6,4) -10.0000 +30.0000i
> (7,4) 1.2500 - 3.7250i
> (5,5) -2.5000 + 7.5000i
> (7,5) -1.2500 + 3.7500i
>
> The same happens in Yt.
>
> Yt =
>
> (2,1) -1.2500 + 3.7500i
> (3,2) -1.6667 + 5.0000i
> (4,2) -1.6667 + 5.0000i
> (5,2) -2.5000 + 7.5000i
> (2,3) 1.2500 - 3.7250i
> (3,3) 1.6667 - 4.9800i
> (6,3) -10.0000 +30.0000i
> (4,4) 1.6667 - 4.9800i
> (6,4) 10.0000 -29.9900i
> (7,4) -1.2500 + 3.7500i
> (5,5) 2.5000 - 7.4850i
> (7,5) 1.2500 - 3.7250i
>
> I would appreciate helping me understand the concept and use of Yf and Yt .
>
> Best Wishes,
> Ehsan
>
