Discussion in 'Homework Help' started by magodiafano, Mar 5, 2011.

1. ### magodiafano Thread Starter New Member

Feb 12, 2011
6
0
I have a question about the circuit in the image:

I know that the Generator 1 is carrying 500 MW of active power and 50 MVar of reative. The voltages magnitudes (linetoline) are 500 Kv at both buses. At bus 1 (gen.1) Van as magnitude 500/sqrt(3) while phase is 0 KV.
I need to find the phase difference between Van and Va'n' and the per phase reactance of the line (R=0).
How could I answer to these two questions?

2. ### Heavydoody Active Member

Jul 31, 2009
140
11
I am afraid this one is a bit beyond my paygrade. On the other hand, maybe my idea can get you started. You know $P, Q, and V_{rms}$. So:

$P=V_{rms} I_{rms} \cos( \phi _v - \phi _i)$
$Q=V_{rms} I_{rms} \sin( \phi _v - \phi _i)$

There are two unknowns $(I_{rms}$ and $(\phi _v - \phi _i))$ and two equations. Once you solve for $(\phi _v - \phi _i)$ you can find $I_{rms}$ and solve for Z. I think...

3. ### magodiafano Thread Starter New Member

Feb 12, 2011
6
0
i just found the unkowns! they were requested in the first exercise.
Irms = 1000000
Thetai = -5.71

4. ### Heavydoody Active Member

Jul 31, 2009
140
11
I was hoping someone else would jump in here, because now I want to know the answer too I came up with a different current (same angle). The thing is, regardless of what you get, the impedance "seen" by the generator on the left includes the impedance of the generator on the right, and I am not sure how you could go about separating it from the reactance of the inductor. Unfortunately, I have a ton of (unrelated) homework of my own...