Power Grid Losses: Thumb Rule Approximations/Guidelines Across Distances

[racookpe1978]

On a separate internet forum, one writer attempted to use a 2006 regional study of 19 wind farms across OK, Kansas and north TX to show that wind energy could generate reliable baseline power for the US if enough wind farms were linked together to brinf overall reliability up to 87%.

Ignoring the other problems involved, I could not find from my power plant desiogn books - which tend to be mechanical/steam/nuclear/turbine/generator/piping and thermodynamics side of the house anyway - any adequate rules for power loss across longer distances. Used to be, a power plant was owned by a regional or city utility company, and that power plant provided power "locally" - the nearest 20 - 40 miles in the 1920's and 30's. Perhaps nearest 100 - 150 miles by the time of rural electricfication, then out to 200 - 300 miles max by the 1960's, right? "Grids" tied these regional power networks together by the 70's - and problems in the late 60's and 70's proved the wisdom of regulating and controlling those grids even more. (Northeast power loss for example provided many "lessons learned" now implemented in whole or in part at least.)

But. as I understand the basics, the "power" from one plant is linked through the high volt network, is synchronized through that network region, but is not "used" much further than the local area. Resistance losses are about 2% in the nearest 100 miles radius, about 3% at 150 - 200 miles, and 5 to 8% further than that, correct? That is, trying to get "power" through the grid from OK to California "could" be done, but you'd lose some 25% to 35% get the current there if there were no intermediate plants on the way. The scheme of linking central US windmills together falls on the need to link all of the separate wind farms together by power lines rated at 100% nameplate rating to transfer just 21% effective power most of the time, then to get that irregular power from the central US to either the east or west coast when the Bermuda high is settled over the entire southeast region.

My analogy should be: You can fill bucket from your garden hose, and you can fill up a 55 gallon barrel from your water hose. You can hook up 1800 feet of garden hose from your faucet to the nearby fire house, and you could get "water pressure" at the other end of the hose, but you would not get enough effective flow to fill the fire truck up while it's trying to fight a fire.

Am I improperly simplifying the issue? Or not presenting even this part of the problem correctly?

 

[crshears]

The only possibly relevant number to this topic that I can recall without cracking open a book was the recommendation that to keep system losses manageable, transmission of power should be at 1 kV or greater per mile.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[tinfoil]

Ontario has an actual renewable generation market that is quite large.
They have calculated loss penalties to its various participants based on their locations and the location of the 'grid' and the 'loads'.
Details can be found at Link.

If you were to extrapolate from that to the continent, the losses would likely be in the 50-60% range, at a gut-level guess.

 

[racookpe1978]

Thank you. I'll look those up.

 

[cuky2000]

Penetration of renewable energy including wind power in large amount in the definitely bring new unexpected issues to all in the power community.

We should be aware and perhaps be flexible to be re-educated to face the unevoidable reality and the challengers ahead of us in the short and mid term.

There are presently great technical tools and option to mitigate the new challengers and particularly to reduce the system losses and increase reliability.

Some of the available resources are UHV transmission, series capacitor compensation, FACTS, HVDC, HTS and others non traditional technologies available to all of us today but slow penetration do to cost and lock of familiarity to a new technology.

We hope the renewable energy can be deliver with the same level of efficiency or perhaps better than the present system performance summarized below.

_{APPROX. AVERAGE LOSSES IN THE US ELECTRICAL T&D SYSTEM:
a) HV Transmissionlines and substations: =2-4% (T. Lines ~2%)
b) MV Distribution system:.........................= 4-6%
Losses at peak are higher due to higher resistance and reactive power consumption.}