Transmission line impedance per mile 1

[rptp]

Hi..
I need help to finding Transmission line impedance per mile.
I dont know formula for line impedance per mile.
is there any software available for calculate transmission line impedance.
we have FOUR 173MW generators at site and and we want to transmit power through 230KV line.
Here I attached part of single line diagram.
this is solar thermal plant.

I would appreciate if somebody help me.

Thanks

 

[cranky108]

If it's just one line I'd calculate it by hand. The Westinghouse T&D book has good formulias for that.
Most of the software that can calculate impedance is too expencive for just a few lines.

 

[wbd]

If you want to find the transmission line impedance, you need to decide what conductor you want to use.

For the conductor size, 1272,in your sketch,it depends on the specific conductor material:

For 1272 Narcissus

0.077199 + j0.729031 ohms/mi for R1 & X1
0.358996 + j2.58558 ohms/mile for R0 & X0

However for 1272 Bittern:

0.0747006 + j 0.721436 ohms/mile for R1 & X1
0.356362 + j2.57799 ohms/mile for R0 &X0

And pole height and GMD will also effect the impedance of the line.

 

[davidbeach]

wbd has made a number of assumptions that are not supported by the information in the sketch. It is impossible to calculate impedance to any where near that precision without knowing exact line geometry. Also with both circuits on a common structure, or even in the same right of way, you have to calculate the mutual impedance between the two lines as well as their self impedances.

 

[wbd]

davidbeach,

As I stated you would also need the pole height and GMD which would affect the overall impedance and performance of the line in respect to losses.

I used a database of line parameters to give the OP a general feel for the impedance of the line and did not include shunt capacitive reactance, conductor temperature, etc.

Your right that I made some assumptions like the OP was looking for the data to do some quick back of the envelope calcs to get a feel for maybe line loss or voltage regulation. I would think that even for a short line like that he would have the line design done by an engineering firm that has software to examine the line for performance and proper setting of relays. I would also imagine that the OP would want the towers and sag of the conductors designed properly for the region that he is located in.

 

[rptp]

Thanks for your help guys.