NY Power Transmission

My understanding is DC will tolerate the transmission of much higher voltages over distance. So longer distance is doable.

This is far above my head, or under the water.

Over my head too.But I have learned a lot, as always.

Power transmission is best done on high voltage to minimize the losses.

Its best explained here.

Yes HVDC current is more efficient at long distances...

..."High-voltage direct-current (HVDC) technology is used for greater efficiency over very long distances (typically hundreds of miles). HVDC technology is also used in submarine power cables (typically longer than 30 miles (50 km)), and in the interchange of power between grids that are not mutually synchronized. HVDC links are used to stabilize large power distribution networks where sudden new loads, or blackouts, in one part of a network can result in synchronization problems and cascading failures."...

https://en.wikipedia.org/wiki/Electric_power_transmission

Nah, its all good

https://en.wikipedia.org/wiki/HVDC_Inter-Island

Plenty in China also (for example)

https://en.wikipedia.org/wiki/Yunnan%E2%80%93Guangdong_HVDC

Yep, we've had the Pacific Intertie for 30 something years now.

It has been done already. England and France are connected in this way.

1961 for the first cross channel link

Now we're linked to France, N Ireland, S Ireland and the Netherlands. The proposed link to Iceland will be a challenge.

One might need plenty of slack in the cable, as Iceland can't make up its mind upon which tectonic plate it wants to be...

Oswego NY is the part that baffles me. The real power generation occurs where Lake Erie dumps to Lake Ontario, via a short river, of course. The Oswego River doesn't seem that well suited for hydro generation, or am I wrong?(I'm assuming no coal or gas generation here)

Oswego is the home of 3 nuke plants (1 to be shut down next year, though), as well as an 1100MW natural gas-fired generating plant. There's a pretty fair amount of power flows through there.

Okay - bafflement eliminated. I was thinking green and hydro, not nuke. Definitely not thinking nuke in Cuomo's state. Given his political beliefs, I assumed he'd try to shut them all down.

He probably just hasn't gotten around to shutting those plants down. Andrew is focused on closing the Indian Point plant. It's close to bazillions of people and has had recurring problems over the years. I wouldn't disagree with him about closing that one. Here's a very recent examination of the state of NY state's nukie plants.

I grew up in TVA (Tennessee Valley Authority) country, which accounts for a lot of my scepticism about nuclear power generation. In my estimation TVA didn't and doesn't do a safe, responsible job managing their nukie plants. Sometimes I wonder if safe operation is possible, given that we are all only human and we sometimes make mistakes.

Cuomo HAS been trying to shut down the Indian Point reactors, because they are in his (& his girlfriend's) "back yard." So far that has been moving ahead. The Fitzpatrick plant in Oswego is owned by the same company (Entergy), and has been a big money-sink for the company while Indian Point has been profitable. Cuomo & the Albany crowd have made some half-hearted efforts to keep Fitz open due to the huge impact on the local economy in jobs & tax revenue, but Entergy is sticking to its guns that they can't continue to run the plant at a multi-million $ loss each year. They won't do anything to keep Fitz open while Andy is trying to shut down Indian Point.

So they keep looking to other "solutions" to squeeze more usable power through the transmission infrastructure, and push for solar, wind, etc. In the meantime, they have totally nixed hydrofracking for natural gas in NY, as well as not approving the "Constitution" gas pipeline across upstate to bring some of the PA gas to the northeastern market.

Hi Walt

I believe capacitance is the problem and this is what burnt out the original transatlantic cables.

With AC there is a constant magnetic field, which is how AC transformers work. When cables are suspended in the air, the EMF is not a problem, but when they are surrounded by water (a much better conductor) then there is a huge power loss.

As explained by someone else, converting DC to AC could only be done by a motor-generator combination in the past, but the world of silicon has now made it economical.

We have a connection between Tasmania and the Australian mainland using this system.

Tony

As explained by someone else, converting DC to AC could only be done by a motor-generator combination in the past, but the world of silicon has now made it economical.

Or in our country's case in the 1950's new high tech Mercury arc valve converters.

Take that RoHS!

Thank you Jack

I believe the Mercury arc valve converters can only do AC to DC and not vis-a-vis, but I didn't know about them, so thank you.

When visiting an old lighthouse I saw the glass lens was floated on mercury, a fascinating deadly liquid.

Tony

No More mercury. Look up ABB HVDC light and classic systems. Each valve is in general, about 20 tonnes. And all water cooled.

http://new.abb.com/docs/default-source/ewea-doc/hvdc-light.pdf?sfvrsn=2

Yes if I remember correctly the ones used in our link were getting phased out during a recent upgrade a few years ago. We only supplied custom bus work for the project.

Mercury arc tubes were use for DC→AC conversion by using control grids making it a thyratron.

The problem with rotary converters and MG set at the voltages involved is flashover.

"We have a connection between Tasmania and the Australian mainland using this system."

Not at the moment we don't.

Basslink failed back in December 2015 due to a fault about 100km offshore.

Poor weather in the notoriously dangerous Bass Strait has delayed repairs to date.

With Tasmania in the grip of a severe drought coupled with their urgency for shutting down coal and gas fired power generation and their refusal to embrace further hydro installations, it looks like they're finally going to pay the price for their poor decisions as rolling blackouts are on the horizon due to lack of supply.

They were going to sell off the Tamar valley gas generator but have now had to recommission it in an attempt to reduce overload.

Thank you for that Spades, I've been hearing about power problems there, but hadn't realised the cable had failed. doh!

HVDC transmits better with less losses. The only major issue is in switching when a very high spike is obtained.

There is a good discussion of HVDC delivery in this thread. My fault, really, since I didn't understand it either.

http://cr4.globalspec.com/thread/107153

We should re-emphasize that even high charging losses are encountered in underwater high voltage AC transmission. DC does not have this problem in either air or water.

So basically Tesla, Westinghouse, and Edison were all partially right, partially wrong, and completely pioneering. Now we have a better Conestoga, let's paint those wagons, and get back under our wandering stars.

Power transmission is majority movement of electrical energy from a generating site. Mostly transmission lines are high voltage three phase AC although single phase AC is used occasionally in railway system. Transmission is good done on high voltage to minimize the losses.

Yes, we have moved on from that slightly in some special cases in the U.S.A.

DC works better than AC for underwater power transmission cabling.

DC high voltage is now more efficient than 3PH AC high voltage over long distances, simply because the equipment to convert to and from DC is so far advanced these days, that this is better than losing x% of power due to AC line coupling to ground through air/wire capacitance (essentially radiated power).