DC transmission cost

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gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
110605-0750 EDT

What is the cost to transfer a KWH by high voltage DC transmission lines?

Clearly at each end of the line there is a fixed up and down voltage translation cost. The transformation ratio will have some impact on this fixed cost, as will the power level.

A big factor is the length of the transmission line.

What is an optimum voltage level?

Is it feasible to consider a 2000 mile line?

At 2000 miles, or some other long distance is $0.01 / KWH feasible?

Obviously the cost needs to include the lost energy in the transmission system as well as the cost of the system.

An associated question is --- what is the cost per KWH for pumped storage where the capacity is for 1 day of energy, and 7 days of energy? Energy being the total demand of the system.

.

.
 

Besoeker

Senior Member
Location
UK
110605-0750 EDT

What is the cost to transfer a KWH by high voltage DC transmission lines?

Clearly at each end of the line there is a fixed up and down voltage translation cost. The transformation ratio will have some impact on this fixed cost, as will the power level.

A big factor is the length of the transmission line.

What is an optimum voltage level?

Is it feasible to consider a 2000 mile line?

At 2000 miles, or some other long distance is $0.01 / KWH feasible?

Obviously the cost needs to include the lost energy in the transmission system as well as the cost of the system.

An associated question is --- what is the cost per KWH for pumped storage where the capacity is for 1 day of energy, and 7 days of energy? Energy being the total demand of the system.
Gar

I don't know the answers to all your questions but here are a few:

There are claims of as little 3% voltage drop for 1000 km. Frankly, I don't believe it. I've posted my basis for that elsewhere and when I find it I'll add it here.

At each end of the line there is a converter or inverter or both in addition to the transformation to other voltages. Initially, I think mercury archaic rectifiers were used but now many use thyristors at both the converter and inverter ends. I think mostly the inverters are mains commutated bridges which means they would need a fairly stiff supply to operate into. Maybe GTOs are used also. ABB are major players in this field and they use GTOs in their MV variable frequency inverters. They might also have scaled them up in a series arrangement for HVDC transmission. There are some smaller units on line using IGBT technology.

Some existing HVDC transmission lines are about 1,000 miles long. Some scheduled to come on line are up to about 1,500 miles long.

On pumped storage, the largest system in UK is Dinorwig in Wales. Actually, the largest in Europe.
It's about 70% efficient by my calculations. And it can provide about 2,000 MVA for five hours. That gives an idea of scale. And energy costs given that it is a net consumer.
 

BJ Conner

Senior Member
Location
97006
Pacific Coast Intertie.

Pacific Coast Intertie.

The pacific Coast intertie runs from near The Dalles Oregon to Southern California.
If your driving around the east side of the Sierras AS in going from LA to Death Valley you will drive under it. A two line system not a multiple of 3 as most transmission systems are.

http://en.wikipedia.org/wiki/Pacific_DC_Intertie

The economics are good but I don't have all the numbers.
A big factor is the losses in the electric field. IF you stand under a 345 line sometimes you can hear the buzz. That buzz is power being dissappated into the air. The higher the voltage the greater the loss. Building and reversing that magnetic field around a transmission line can eat up a lot of power.

The inverters and converters limit the power that can be transmitted. If the power gird of Southern California were connected to The northwest grid it could in theory draw all the power out of the northwest. As lights went on in LA they would go dim in Wenatchee and Portland.
The inverter station at Sylmar acts like a 3,100 MW generator. When it reaches 3,100 MW output that's it, it can't suck more by drawing down the voltage.

They are used because they are more efficient and can limit the power transmitted.
There are a couple out of North Dakota (where there is lots of power ) over to Minnesota.
There are more out there and will be even more as windfarms are built in the Flyover Zone.
Google is your friend, look for "HVDC";)
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
IF you stand under a 345 line sometimes you can hear the buzz. That buzz is power being dissappated into the air.

I live near our 345 lines. The buzz is the insulators vibrating. If you are under a brand new line, no buzz.

If you turn your tick tracer on and place it on the dash of your vehicle, it will indicate as you drive under a 345 k line.
 

BJ Conner

Senior Member
Location
97006
New Lines Buzz old Lines Buzz

New Lines Buzz old Lines Buzz

I live near our 345 lines. The buzz is the insulators vibrating. If you are under a brand new line, no buzz.

If you turn your tick tracer on and place it on the dash of your vehicle, it will indicate as you drive under a 345 k line.

Old Dirty insulators make noise, new one in fog can be very noisy. The magnetic field around an AC transmission reverses 60 times a second.

rTick tracer? Try walking under a 345 KV line holding an 8' flourscent tube over your head. Do it in mid span Insulators can be clean or dirty, old or new.:cool:
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
Old Dirty insulators make noise, new one in fog can be very noisy. The magnetic field around an AC transmission reverses 60 times a second.

rTick tracer? Try walking under a 345 KV line holding an 8' flourscent tube over your head. Do it in mid span Insulators can be clean or dirty, old or new.:cool:

When I was working on a peaker that fed a 345 we had to walk past the yard. When it was rainy/foggy the lines would exhibit corona effect at the insulators and it was pretty spooky in the dark at 6:30 AM. This was a new build, so you are correct, new insulators can make noises, too. But it wasn't like a buzzing sound, it was better described as a zap or a sizzling noise. A buzz is what a transformer makes. A sizzle is what a welder makes.

Semi-technically, of course.
 

gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
110606-2054 EDT

The goal of my original post was to get some rough idea on costs. There are many individuals that make claims that DC transmission is very expensive and good for only single source and single destination operation, and not over short distances. The very expensive part is what I want to know about. I can intuitively agree with the two point and long distance part of their statements. Does it cost $0.001/KWH for transmission , or $0.01, or $0.10?

A very long time ago 40s or 50s my uncle said that the distribution of customer cost per KWH, total cost was $0.025/KWH at that time, was about equally distributed between generator plant production, distribution, and general overhead. There were not extremely large grids at that time. Thus, high voltage, medium, and low voltage distribution costs totaled about $0.008/KWH.

If long distance transfer cost can be low, then there should be no problem putting wind and solar where it is optimum. For that matter geothermal, very deep wells.


On to pumped storage. My understanding is the Ludington pumped storage facility is about 80% efficient. This means one gets back 80% of the energy put into storage. If the raw cost of electricity is $0.03/KWH, then the cost as a result of losses for pumped storage is about $0.006. To this has to be added the capital cost of the system. So what is a realistic cost for this storage. I would think better than batteries. My understanding is that at Ludington the major problem is fish kill. Apparently new turbines are being designed to reduce the problem.

I have a guess that Michigan could have a very large business storing energy using pumped storage with long distance transmission. There is talk of some large wind farms out in lake Michigan.

.
 

BJ Conner

Senior Member
Location
97006
Corona Discharge

Corona Discharge

345 KV and higher voltages use bundeled conductors to reduce the mean geometric radius of the conductors. It means that 2 or 3 conductors bundeld together will dishcarge less into the air than one.
HV substations will have big ( 12-24 diameter and made from 1-2 pipe) rings around bus terminations, expansion joints, trasformer bushings etc for the same reason. They spark or dump current out into the air less ( and save energy).
A nick or a burr on a substation bus is easy to find on a humid night. There is a little blue light where it is and you can pick them up on a reciever.
 

Besoeker

Senior Member
Location
UK
Indeed, but they are the big burly American watts, not the wimpy UK watts like they have on your side of the pond.

1 American mW = 1 UK MW.

:cool:
Well, well, well!
James Watt was a Brit.
You can't go redefining OUR units to suit your inflated ego!!!!!
:)
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
Maybe not, though....
The Shire horse breed is from England (which is part of the UK), the Clydesdale is from Scotland (also part of the UK)....

:grin:

Yeah, well tell that to Big Jake.

http://www.wiscnews.com/portagedail...cle_7f402b66-4781-11df-a981-001cc4c002e0.html

Here is my favorite part:

Jerry Gilbert, co-owner of Smokey Hollow Farm, said a certificate from Guinness World Records in England arrived at the farm, by express delivery, in late March.

Smokey Hollow Farm is in Wisconsin. So there.

:cool:
 
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