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Author Topic: Could high voltage power lines make the grid more efficient?  (Read 3822 times)

Offline thedoc

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Technology company ABB are working on developing high voltage systems, which they think could transport power further and more efficiently.
Read a transcript of the interview by clicking here
or Listen to it now or [download as MP3]
« Last Edit: 13/05/2014 21:30:01 by _system »


 

Offline homebrewer

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Yes, 1100 Kilo volts, 50 Hz AC systems planned as part of the Trans European Electricity Network will be more efficient than current lower voltage grids used throughout Europe.

The responsibility for this power lines loss are in general,  I2R losses in the power lines and the mains transformers cores.

So by raising the voltage of the High Voltage power lines to 1100 Kilo-volts, I2R losses are reduced in the power lines and in modern substation transformer cores. But this gain comes at a very High Price, both financially and economically and poses certain concerns for home security.

A better choice would have been a Trans European Network, still standardizing at 1100 Kilo-volts, but running at say 100 Hz, by replacing the substation transformers with large High Voltage switch mode power supplies to which the lower main voltages at 50 Hz can be derived from. This way, the only loss would be I2R loss in the High Voltage- power lines, + a app 2.5 % loss in the High Voltage switch mode power supplies in the substation. The higher frequency in the High Voltage power lines, would allow for a higher efficiency of the use of electricity for industry and commerce.
« Last Edit: 17/05/2014 12:19:19 by homebrewer »
 

Offline chris

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Actually, ABB are talking about using DC transmission and inverting to AC at the consumer end. The losses are substantially lower this way.

Chris
 

Offline homebrewer

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Hi Chris,

Thank for your comment, I had not been aware of the ABB "DC route".

Certainly a very interesting, but very much more expensive to implement
than using some of the existing infrastructure.

In the current financial climate I can not see that the EU has to means to
rewire Europe to implement a 1100 Kilo volt grid system, from the generator
to the end user via a switched mode power supply access.

I think when the first 100 Million Euro have been spend by ABB, our
European masters will drop the idea and bury this white elephant.



« Last Edit: 18/05/2014 00:55:35 by homebrewer »
 

Offline alancalverd

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quote from the transcript
Quote
Itís high voltage DC, that the percentage of power loss is around 3%.  When you compare that to AC, the power that we lose is between 30 and 40%. So, it makes good economic and commercial sense to go for HVDC.

This doesn't stack up against the actual loss from the 400 kV UK national grid, which is around 3%. Total loss throughout the distribution system down to 230V (domestic) is about 12%, and rather better (around 6%) at industrial (11 kV) intakes.   

Whilst it's true that a DC supergrid with local inverters gets around the problem of phase synchronisation for suppliers, it doesn't make the low voltage distribution end any more efficient. You can't pipe 1.1 MVDC into a home or even an existing factory, so the only saving will be in the long haul supergrid sector. But increasing the transmission voltage will increase corona losses (and make them more weather dependent) so the net gain will be very small. It makes sense to go for the highest available voltage when building a brand new grid or inter-grid sharing line, but it's doubtful whether any significant national grid in the EU needs or could tolerate complete rewiring.
 

Offline evan_au

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Another advantage of High-Voltage DC is where the lines need to go underwater, where capacitance loss is far higher than for wires hanging in air.

This may be of advantage for England-France, Wales-Ireland, Denmark-Sweden or Gibraltar to solar power stations in North Africa.
« Last Edit: 18/05/2014 04:06:32 by evan_au »
 

Offline CliffordK

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At least around here, the "grid" is made up of multiple parts. 

A large portion of the State's power is generated along the Columbia River, and distributed through up to hundreds of miles of main feeder lines to other parts of the state. 

The local distribution grid will have a somewhat lower power high voltage line, connected to a transformer for every few houses. 

It would be a nightmare to upgrade the entire local distribution grid, and may not be as dependable as the current transformers. 

However, I wonder if the main feeder lines could be upgraded, perhaps reusing some of the existing towers and wires.  Would they need new insulators?  Reduction from 3 wires to two?  Nonetheless, rather than replacing a million or so residential transformers, one might get away with just upgrading a few substations.  Potentially just install new DC main feeder lines whenever a new line is put in, without actively changing out the old, at least at first, until an upgrade is naturally needed due to aging equipment.
 

Offline evan_au

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Quote
I wonder if the main feeder lines could be upgraded, perhaps reusing some of the existing towers and wires
The length of the insulators is directly related to the voltage being carried on the line. So you can't carry 1 MV DC on a transmission line originally designed for (say) 330kV AC, which has a peak voltage on one phase of 330kV x d21848cdd835abcb491be1f151e9b6c6.gif= 466kV (or slightly higher if you measure between phases).

AC transmission towers usually carry 3 or 6 wires. 3 wires carry three phases of a single circuit.

6 wires are used as 2 circuits of 3 wires each. This allows essential maintenance to be done by shutting down one of the circuits at off-peak hours, and still supplying the load through the other circuit (if it's not possible to repair it while it's "live").

The same basic tower design could be reconfigured as 3 circuits of 2 wires, although 2 circuits of 2 wires would also be quite usable, and would allow more separation between phases.
 

Offline highvoltpower

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Yes, we can transfer power that is the product of voltage and current. We can transfer the total no of power at high voltage, low current or high current low voltage. Power loss is goes up very quickly with current. Therefore we worse the current as far likely by increasing the voltage. Some other advantage for high voltage DC is to increasing the capacity of associate existing power system wherever extra wires area difficult or costly to install.
 

Offline syhprum

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One underwater transmission line that should be built is Iceland to the UK to tap the abundant geothermal power that can be generated there
 

Offline alancalverd

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It's already on the drawing board!
 

Offline syhprum

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It's been on the drawing board for as long as fusion reactors!
I think the Icelanders have a love/hate relationship with geothermal power that causes a lot of contamination they like their warm apartment's and swimming pools but are not keen to have too much of it
« Last Edit: 07/04/2016 13:48:56 by syhprum »
 

Offline highvoltpower

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 (HVDC) electric control communication system usages direct power for the bulk communication of electrical power, reduce the energy lost in the conflict of the cables. Provide the benefit to increasing the capacity of current power grid circumstances wherever extra wires are hard and classy to install.
 

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