Hello,
When I calculate the power flow from bus i to bus j, I set
Sij=Pij+1j*Qij=V_i*(I_ij^*). From the real part, I get Pij, which matches
the result of matpower. From the imaginary part, I get Qij, which doesn't
match the result of matpower. So what is wrong with my calculation? Thanks.
Jerry.
On Sun, Apr 24, 2011 at 11:51 PM, jigna pandya
<jigna_pandya2...@yahoo.com>wrote:
> hello,
> Reactive power flow balance equation is as follows:
> Qgeneration+Qcharging=Qload+Qloss .
> (Due to presence of capacitive effect, transmission line injects reactive
> power in to the system.)
> so Qfrombus+Qtobus=Qloss doesn't hold.
>
> regards
>
> ------------------------------
> *From:* z qin <zhengr...@gmail.com>
> *To:* matpower-l <matpowe...@cornell.edu>
> *Sent:* Mon, April 25, 2011 8:19:11 AM
> *Subject:* Help on the reactive power flow in matpower.
>
> Hello,
>
> I ran runopf('case9.m') and got the result below. In some branches (1, 4
> and 7), Qfrombus+Qtobus=Qloss. However for the rest branches,
> Qfrombus+Qtobus=Qloss doesn't hold. Could someone explain for me? I had
> thought that
> Qij=|Vi|*|Vi|*Bij+|Vi|*|Vj|*(Gij*sin(theta_i-theta_j)-Bij*cos(theta_i-theta_j),
> but it seems that it is wrong. Thanks a lot.
>
> Btw, here is how I calculate Pij and Qij. Sij=Pij+1j*Qij=V_i*(I_ij^*), from
> the real part, I get Pij, which seems correct; from the imaginary part, I
> got Qij, which seems wrong.
>
> Best,
>
> Jerry.
>
>
> 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 4 89.80 12.94 -89.80 -9.02 0.000
> 3.92
> 2 4 5 35.22 -3.90 -35.04 -13.87 0.181
> 0.98
> 3 5 6 -54.96 -16.13 55.97 -22.18 1.010
> 4.40
> 4 3 6 94.19 -22.62 -94.19 27.28 0.000
> 4.66
> 5 6 7 38.22 -5.10 -38.07 -18.68 0.149
> 1.26
> 6 7 8 -61.93 -16.32 62.21 0.82 0.279
> 2.36
> 7 8 2 -134.32 9.32 134.32 0.05 0.000
> 9.36
> 8 8 9 72.11 -10.14 -70.72 -18.94 1.394
> 7.01
> 9 9 4 -54.28 -31.06 54.58 12.92 0.295
> 2.51
>
>
>
>
--
------------------------------------------------------------------------------------
Zhengrui (Jerry) Qin
Computer Science
College of William and Mary
Williamsburg, VA 23185
------------------------------------------------------------------------------------
