How much power can transit through a power line linking generation and load?

First things first I am not an electrical engineer at all so please bear that in mind when you reply/comment.

I am looking at the following problem, I have a power line which connects a windfarm to a consumer.

I make the assumption that the consumer will always be able to consume the power provided by the windfarm.

I assume that the windfarm actual power generation capacity varies between zero and a maximum that is exceeding the capacity of the power line.

My question is: How can I determine the maximum amount of power that can transit through the power line from the windfarm to the consumer before curtailment in required ? or the transmission line upgraded.

So far I have used the following: where I(Amps) is the maximum current that the line can handle before melting. Vphase is the voltage of the line (lets assume a transmission rated at 400 kv). and pf the power factor of say 0.8.

Using this equation and assuming I is 1000 amps, Vphase 400 kv and pf 0.8, I find that the maximum power that can transit through the line is 692.8 MVA or 554.2 MW.

If that is true (which I suspect it isn't), am I correct in thinking that if the wind blows hard and the windfarm could produce over 554.2 MW then all that excess power capacity would have to be curtailed ?

• If the power line not very short, you have to deal with transmission line effects. When using underground cables, their capacitance limits the useful maximum length to about 80 km. – Uwe Feb 20 at 17:30
• This really depends on distance between wind farm and load and the conductors chosen. – StainlessSteelRat Feb 20 at 21:10
• Can these losses be estimated simply ? e.g. using an equation which takes the distance between the power source and the load and the initial power amount ? For example, something that tells me that if I have a windfarm producing 250 MW and that the consumer is at the other end of a 100 km line he will only receive 200 MW. – Sorade Feb 21 at 15:46