I don't know about the city governments, but I recall years ago a relativel y new mall had become very popular and as the county population grew the pa rking lot became so crowed it was limiting sales. I thought this would be a big problem for the mall, but then I realized it was the opposite. They really didn't care about the convenience to the shoppers. The fact was the mall was working at full capacity and the businesses all loved it!
After another 15 years they upgraded the road and the mall improved ingress /egress.
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Rick C.
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And it happened - a concrete demonstration of how perilously close to the limit the UK power system is.
I hope this will finally get through to Rick C that EV infrastructure isn't as simple as it is in his neighbourhood. But I doubt it
Yesterday *large*[1] parts of the UK had power cut because two plants went offline within two minutes - one gas plant, one wind plant. Yup, wind power does suddenly stop.
[1] There blackouts across the Midlands, the South East, South West, North West and north east of England, and Wales.
All you have to do is look at the compass points to realise how widespread that was.
And in mid summer when you might expect things to be safe.
It seems likely that the initial problem which was the first gas turbine generator dropping out wasn't dealt with in the two minutes before a second independent failure of a wind turbine farm. The two being offline together then took the mains frequency sufficiently far out of bounds that some inverters stopped as well. Cascade failure followed.
Dinorwig can start in under 20s so someone wasn't paying attention...
The thing that they have failed to model adequately for grid management is that conventional turbine generators have huge synchronised spinning rotors that offer considerable inertia to changes in grid frequency.
By comparison semiconductor inverters seem to offer almost none and give up completely if they find df/ft too large or f outside accepted bounds. I don't see why this needs to be the case provided that the devices are protected from overload - a couple of percent frequency variation shouldn't take a decent power transformer into saturation.
It was astonishing how widespread the UK power cuts were for a fault that was concentrated in the SE near Cambridgeshire - they lost Newcastle Airport nearly 300 miles away as a direct result.
NHS hospitals that beancounters had put on the load shedding cheapest tariff found themselves without any power at all - and the odd one discovered their emergency backup generators didn't work either.
Lucky it happened at 5pm when most scheduled operations were over.
There appeared to be parts of the London underground that lacked emergency lighting too (or if they had it then it failed too work).
It was also rather discouraging how few of the major systems recovered gracefully from a sudden loss of power when power *was* restored after about an hour. The trains are still a complete mess today.
That wide geographic spread is a bit weird - the protection system is supposed to limit the contagion and shed the right sorts of load first and nearby. We were not cut off but others in major cities were.
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Offgen is looking into it. Don't hold your breath...
So it seems. Gridwatch shows down to 49Hz when the limit is 49.5Hz.
I look forward to seeing more in the trade press, e.g. the IET and comp.risks
Maybe it was otherwise occupied? :)
Maybe the velocity of the cascade was both too fast for humans, and too slow for the automated system on the other side of the country to kick in.
I pretty sure they know that and have modelled it :) It may well be that load shedding occurs to prevent excessive stress being put on the remaining rotors.
Yes indeed.
I think it has got some politicians attention. Whether they will continue to think about it is questionable, especially in the face of the disaster of their own making.
Classic.
A few months ago my daughter was waiting in the anteroom all day and night, and the operation finally happened at 7:30pm.
That's unsurprising. You can't have a train from X; you have to have a train to X followed by a train from X :)
Another aspect is becoming apparent. The homes affected appear to be in a fractal patchwork, rather than across a whole area.
For example, I didn't notice anything, but 4 and 10 miles away: "the company?s website shows 194 homes in Keynsham and 25 in Nailsea are still [yesterday] without electricity."
Yup, wind power stops suddenly, but not because the wind stopped blowing.
"Energy watchdog Ofgem has demanded an urgent report from National Grid int o how the failure happened as parts of the UK were battered by strong winds and heavy rain."
?The first generator to disconnect was a gas fired plant at Little Barford at 16:58. Two minutes later Hornsea Offshore wind farm seems to hav e disconnected."
No one said the wind stopped blowing. lol
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Rick C.
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Keep in mind that trains, like airlines, depend on the trains being where t hey need to be in order to maintain the schedule. If weather grounds a por tion of the country, planes can't get where they need to be in order to con tinue the schedule without disruption and the entire country can be affecte d. When I say "country" I am thinking of the US. If you are in the UK ple ase substitute "EU".
I'm sure a similar problem happens with trains. The move a lot slower and travel one dimensionally, so it can be hard to get things straightened out.
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Rick C.
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Can't say about the UK, but in the US areas are often provided with power f rom more than one source by redundant paths. If one fails, they draw more power from another. At times this can result in an overload of any single circuit. Not surprising failures were sporadic. When you stress a system to it's max you find weak spots first, where ever they are.
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Rick C.
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Perhaps different switch centers have differing under-frequency-lockout sensitivity and responsiveness delay?
If so that may not be quite so stupid, although I can't see why the cutout had to be set so close to the regulatory limit, most loads would still be perfectly content at 47Hz for instance.
There was independent damage to some local infrastructure by lightning strikes in addition to the main event. A village not far from me took a direct hit last night. We just got a to see a spectacular noisy display.
I think they got most of the load shedding stuff back on within a couple of hours. Most times they get us back on within half a day unless there is major damage affecting larger towns and cities in which case we wait.
Most of us have other ways of heating and lighting our homes since the usual mode of failure is severe winter storm tree breaks the line.
er from more than one source by redundant paths. If one fails, they draw m ore power from another. At times this can result in an overload of any sin gle circuit. Not surprising failures were sporadic. When you stress a sys tem to it's max you find weak spots first, where ever they are.
No one said the initial problem was the grid. The point is as events unfol ded parts of the grid were stressed including both generation and transmiss ion.
Slightly different problem. Simply being down may not have caused this pro blem. Everyone seems to focus on the fact that they went down within two m inutes of one another. That clearly precluded any adjustments to generatio n and distribution before problems started happening.
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Rick C.
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There was a truly spectacular lightning storm 15 miles away a couple of weeks ago. Around a strike a second for >>10 minutes, i.e. until I got bored.
Yes, and I think it was a few hours this time too.
But then I remember revising for exams by candlelight, back in the 70s :(
I've now got a pocket-money second-hand UPS which may or may not work; I've yet to have a chance to look at it. Principle use case: keeping freezer cold after a no-deal brexit.
I would speculate it is more about the concern that a significant aberration is happening and it is simply best to go offline rather than continue to draw power.
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Rick C.
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