Maximum lenght of a overhead line
Maximum lenght of a overhead line
(OP)
Hi,
I'm trying to define the maximum length of overhead lines based on it's characteristics (R,X,max current, max power) and voltage level (high voltage).
So basically, I want to know what's the maximal length of 10, 20, 35, 110, 220, 400 kV line that is acceptable due to voltage drops and other factors.
I found on Wikipedia this: "Very approximately, the allowable product of line length and maximum load is proportional to the square of the system voltage" - (http://en.wikipedia.org/wiki/Electric_power_transm... - Capacity heading).
So, if I have a 110kV line with a max load of 122 MVA, it turns that the "allowable" lenght is 99.18. but wikipedia doesn't mention if it's miles or kilometers.
Is this formula applicable for my issue? Is it correct? Is it for miles of kilometers?
Is there another way to calculate this?
Thanks in advance,
keesem
I'm trying to define the maximum length of overhead lines based on it's characteristics (R,X,max current, max power) and voltage level (high voltage).
So basically, I want to know what's the maximal length of 10, 20, 35, 110, 220, 400 kV line that is acceptable due to voltage drops and other factors.
I found on Wikipedia this: "Very approximately, the allowable product of line length and maximum load is proportional to the square of the system voltage" - (http://en.wikipedia.org/wiki/Electric_power_transm... - Capacity heading).
So, if I have a 110kV line with a max load of 122 MVA, it turns that the "allowable" lenght is 99.18. but wikipedia doesn't mention if it's miles or kilometers.
Is this formula applicable for my issue? Is it correct? Is it for miles of kilometers?
Is there another way to calculate this?
Thanks in advance,
keesem






RE: Maximum lenght of a overhead line
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Maximum lenght of a overhead line
I supose like some river crossings I have seen, you could use spacer arms, or arms supported by steel wires.
The company I work for once would use pull down structures in the valleys to control the spacing and spans. They were wood structures weighed with concerte to hold the lines down. They also had some seasonal pull down structures.
RE: Maximum lenght of a overhead line
1.)thermal (short lines)
2.)voltage drop
3.)power transfer (long lines)
Real power delivered is given roughly by:
P=VrVs/X*sin(d)
Vr=Receiving voltage
Vs=Sending voltage
X=line reactance
d=phase angle across the line
Max practical angle is about 35 degrees.
RE: Maximum lenght of a overhead line
RE: Maximum lenght of a overhead line
RE: Maximum lenght of a overhead line
resistance R is fixed. For a fixed resistance, the heat losses dissipated is = V² x R. Therefore is you are using selected conductor size and a given acceptable loss, the selection is governed by V².
RE: Maximum lenght of a overhead line
Surge Impedance Loading (SIL) is another conceptual way to discuss the capacity of transmission lines as described in this paper: http://arproducts.org/pdf/ehv_transmission_line_ca...
RE: Maximum lenght of a overhead line
RE: Maximum lenght of a overhead line
RE: Maximum lenght of a overhead line
RE: Maximum lenght of a overhead line