Ultra High Voltage DC Power Transmission.

Northwest China's Xinjiang Uygur autonomous region has become one of the major regions taking the lead in China's renewable energy push, thanks to long-distance, large-capacity and low-loss ultrahigh-voltage power grids.

The region currently has 56 power transmission lines with a total length of 7,764 km, which have played a major role in boosting local economies and facilitating the consumption of more renewable energy.

The region, with an abundance of strong winds and long hours of sunlight, has transmitted plenty of renewable energy resources to energy-hungry coastal regions. By the end of October, the region boasted 107 million kilowatts of total installed capacity for power connected to the grid.

Another example is the Qinghai-Henan ultrahigh-voltage direct-current project, a 1,587-km, 800-kilovolt DC line to transmit renewable energy from the country's western parts to central parts. The Qinghai DC project kicked off construction on Oct 15 last year and is likely to commence operations by the end of the 14th Five-Year Plan period, said State Power Investment, its operator.

As the government plans to build massive wind and solar power facilities in the country's Gobi Desert and other arid regions, it is expected that regions like the Xinjiang Uygur autonomous region and Qinghai province are expected to become major clean energy industry bases in the country, which will in turn help increase demand for ultrahigh-voltage transmission lines in the country, said Wei Hanyang, a power market analyst at research firm BloombergNEF.

Reply to
sid
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This post was brought to you courtesy of the Central Propaganda Department of the Chinese Government.

So they plan to pollute the unique and pristine Gobi Desert. Wonderful.

And why are they opening so many coal-fired power stations and burning record amounts of coal?

They needn't do any of the above. They have some good designs for nuclear power stations, so they ought to be building them like fury. I know they're building some, but not nearly enough.

Reply to
Chris Hogg

They are building anything and everything they can, but china is due for an epic financial crash that will wreck its economy for 50 years.

That's why they want to start a war.

Reply to
The Natural Philosopher

So..... What I want to know is why DC, surely the problem of converting it all to AC has to have losses? DC fell out of favour back in the early days as you could not use transformers on DC. Brian

Reply to
Brian Gaff (Sofa

Hasn't this been discussed in this group fairly recently with reference to the links to France/Norway etc.?

Reply to
alan_m

Well that is an easy one. It's for the same reason that undersea (and long underground) links are DC, namely dielectric losses. These are of course much lower for transmission towers in air than for the substantial insulated cables required underground or undersea, but not negligible for long lines.

There's a point at which the capital cost (and losses) in converters is less than the AC losses.

Reply to
newshound

Its not dielectric losses as much as a perfectly rotten power factor that means that there are huge out of phase currents, raising resistive losses to unacceptable levels. This is due to the capacitance to earth of a cable surrounded by salt water.

There is one further point, and that is synchronisation of grids. Very large grids spanning more than about 1000 miles start to run into time delay issues via the various parts that end up with large out of phase currents being drawn. DC interconnectors between segments avoid this problem.

Likewise if grids are not phase locked, some sort of AC-DC-AC coversion is necessary anyway.

Conversion efficiencies are pretty high really - very high 90s percentage wise.

Reply to
The Natural Philosopher

Actually completely untrue. The gas shock is forcing all countries to re-examine their nuclear power programs, and there is a large voice calling for nuclear power across all of the world.

Reply to
The Natural Philosopher

Long before undersea power cable were in use. the USSR was using Dc to cross from west to East.

Reply to
charles

Its a pity you didnt read the rest of what I wrote.

Reply to
The Natural Philosopher

For same power transfer, DC also has lower (x 0.707) peak voltage of AC?

Reply to
Ian Jackson

So, the pylons are cheaper to build?

Reply to
GB

Yes. But its not a huge issue. You size the voltage to the breakdown capabilities of your insulator and indeed your inverter semiconductors (or valves, whichever)...

I think the normal undersea runs at about 275KV. That's pretty high for semiconductors

For a 500MW cable that's still 2000A....

Reply to
The Natural Philosopher

Much much cheaper. Cable uses the air for insulation, and to cool the cables .

Far far less capacitance to ground.

No need to dig holes in the ground to lay it.

Reply to
The Natural Philosopher

No, I meant that DC pylons are cheaper than AC.

Apart from anything else, you don't need to transmit three phases, and keep those separated. So, whilst you might want several conductors, because those are easier to handle and rig, they can be in one bundle at the top of the tower.

Reply to
GB

Oh. Sorry. Not much in it really.

Well you don't *need* to 'transmit' three phases for AC either....

Reply to
The Natural Philosopher

As maybe but we need the power now!, not in years time best to keep the old coal plants on the go for now I think lights out wouldn't go down well with the populace!....

Reply to
tony sayer

Germany is not 'most countries' - it is the exception to the rule, because Germans are very very green and wet behind the ears. And will end up importing all their power from countries that are not.

Since when have nukes been considered 'green'

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Now that is not up to date news.

E.g. Belgium which is heavily nuclear is looking to SMRs to replace its massive nuclear fleet.

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The surge in global energy costs is reigniting the debate on Italy?s no-nuclear stance.

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And so on.

The reality is that in the EU with proportional representation and the greens as kingmakers, Nuclear has simply been off the agenda.,

But people are getting heartily sick of Greens and are increasingly leaving them on the side of the plate.

Reply to
The Natural Philosopher

Oops yes. Long time since I did this stuff.

:-)

Reply to
newshound

The EU, beginning to realise the stupidity of its total commitment to renewables, has now decided that natural gas and nuclear are 'green'!

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Reply to
Chris Hogg

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