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What Happened in the UK Blackouts?

mitchoneill.com

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Re: What Happened in the UK Blackouts?

#31

Post by mytailorisrich »

tripzilch wrote: post #23
mytailorisrich wrote: post #13

Earlier quoted context omitted.

All the issues I mentioned are obvious, and so are the potential problems you describe. This is not a question of "it's easy to say in hindsight" as these are the key issues that must be covered by standard planning. This blackout made a lot of noise because of this (apart from the actual disruption, obviously).

Do you have background in the field of giant power supply fault tolerance backup mishap management strategies, or something? Or are you just stating and assuming all of this is obvious, covered by standard planning, instead of easy to say in hindsight? Cause you're making a lot of statements, saying it is such, without backing it up. Maybe it is super obvious, but personally I'm impressed by the strategies that were…

Would you not prioritise an airport, a hospital, the railway, over residential areas?

Do you not think that trains should be able to resume ASAP? Do you not think that "it never happened before" is not a valid reason to be unprepared?

Do you not think that "we never had to use it before" is not a valid reason to explain why an emergency generator might not work when needed?

What backing up do you need?

Re: What Happened in the UK Blackouts?

#32

Post by pbhjpbhj »

pm215 wrote: post #20

The article says near the bottom "At the time [the GT1A generator tripped] there was 4000MW of unused generation in reserve, and if only a fraction of this reserve was instructed to dispatch within 60 seconds of the initial loss it’s very likely that load shedding would have not occurred." My understanding was that having reserves available within 30-60s was pretty expensive, and that that would have been what was us…

Might be pumped water storage like "Electric Mountain" in North Wales (there's some in Scotland too, not sure what the total pumped storage on the grid is). They pump water to remove excess power from the grid and then run in reverse to generate. Their 0-100% is O(1minute) IIRC, actually on the website they say:

>"Synchronised and spinning-in-air emergency load pick-up rate from standby: 0 to 1,320 MW in 12 seconds" (https://www.electricmountain.co.uk/Dinorwig-Power-Station)

Electric Mountain are definitely used for frequency management. Again IIRC, they're the fastest response on the grid. If you get chance to do the tour (it's just below Mount Snowdon) I'd recommend it.

Re: What Happened in the UK Blackouts?

#34

Post by spzb »

bonzini wrote: post #17
Zenst wrote: post #8

Earlier quoted context omitted.

Nice article covering frfequncy importance at grid level:- https://www.drax.com/energy-policy/need-whole-country-freque... Though I'm not sure on the details of a frequency drop and impact upon your house in exacting details. Equally I'm not up on substations (did work on IT for large util company many decades ago, but not field engineering). But the first safety control from supply to the home, would be the distribu…

That website has had me nerd-sniped. Another great one is on "black start": https://www.drax.com/technology/black-start-important-back-p...

You might also enjoy this one http://www.gridwatch.templar.co.uk/index.php

Re: What Happened in the UK Blackouts?

#35

Post by mytailorisrich »

Zenst wrote: post #30
mytailorisrich wrote: post #25

Earlier quoted context omitted.

It's clear that there were issues at hospitals (as expected cynical me thinks, knowing British healthcare...) but the fact that key infrastructure lost power does points to issues at the grid level as well (because sites that lost power did so based on grid procedures).

When they cut the power to an area, they can't selectively keep isolated locations active unless they are isolated in that they operate upon their own spur. That is why Hospitals would be deemed critical and important not to cut out, they are handled by onsight failover power supply in the form of backup generators. In this case, it was like asking somebody to be able to catch a ball, they say they are ready and yet…

I'm sure that they will learn lessons that railways, hospitals, airports should perhaps not be the first to lose power, that trains should be able to restart quickly, and that generators should be comprehensively tested to respond to real situations, and it will be no-one's fault.

I fully agree with you that this is the likely outcome.

Re: What Happened in the UK Blackouts?

#36

Post by pbhjpbhj »

kzrdude wrote: post #22

At one stage, they have to shed load (turn power off), and that sounds totally reasonable. How are these areas divided, how does one turn power off for a whole area, and how is it decided who to cut from power (temporarily)?

From the little I know UK settlements have substations that serve something like 1000 homes. Older ones are open air affairs, newer ones are prefabbed enclosed buildings. They're oil cooled transformers and switching gear. One serves the village where my parents live, in a city there are two within about 400m of me (serving different neighbourhoods). Sometimes a neighbourhood will trip out, like in a thunderstorm; or get turned off (maintenance). I assume that the central grid has a switching order for these to be turned off to maintain essential supply. Factories, hospitals, and such have their own substations.

Re: What Happened in the UK Blackouts?

#37

Post by pbhjpbhj »

Zenst wrote: post #8
bonzini wrote: post #5

Earlier quoted context omitted.

The main problem with frequency mismatch is that when two power sources "meet" with different frequency the effect can be catastrophic, because the faster generator pulls the slower (think of the "hares" in 3000-10000 m running competitions) and typically both end up breaking.

Nice article covering frfequncy importance at grid level:- https://www.drax.com/energy-policy/need-whole-country-freque... Though I'm not sure on the details of a frequency drop and impact upon your house in exacting details. Equally I'm not up on substations (did work on IT for large util company many decades ago, but not field engineering). But the first safety control from supply to the home, would be the distribu…

From that article:

>"In Japan, the western half of the country runs at 60Hz, and the eastern half of the country runs at 50Hz – a string of power stations across the middle of the country steps up and down the frequency of the electricity as it flows between the two grids." //

That's, err, curious.

Re: What Happened in the UK Blackouts?

#38

Post by OJFord »

rwmj wrote: post #33

Why does frequency drop when the system is overloaded?

ELY5: When you're at a playground, and you're pushing the roundabout round and round, it gets harder and you get slower the more kids jump on it, right?

ELY not 5, but I'm no expert either: in terms of phase sources like generators lead [0] sinks, by an amount proportional to their over-production; so the more sunk, the less they lead, and the lower the frequency.

[0]: https://en.wikipedia.org/wiki/Leading_and_lagging_current

See also: https://en.wikipedia.org/wiki/Power_factor

Re: What Happened in the UK Blackouts?

#39

Post by phire »

fyfy18 wrote: post #3

What affect does the frequency drop have to home users? Is there protection in the substations near to homes that will cut off the power completely if the frequency goes out of range?

Most things in a modern home don't care about frequency.

The problem is mostly at the generation end. The electrical grid is essentially distributed transmission locking all the generators across country together. They will all rotate in sync at the same speed/phase, it might as well be a mechanical linkage.

The entire system is under too much load and the generators are all physically slowing down. Unfortunately the generators are all designed to operate over a very narrow frequency range. If the frequency continues to drop, the safety systems will kick in to protect the generator.

If the load isn't reduced, more and more generators will drop off the network and there will be less and less supply to meet the demand. The frequency will drop lower and lower. Eventually the whole network will drop to zero and nobody will have power.

It's basically the same thing as stalling an engine.

Re: What Happened in the UK Blackouts?

#40

Post by arethuza »

pbhjpbhj wrote: post #32
pm215 wrote: post #20

The article says near the bottom "At the time [the GT1A generator tripped] there was 4000MW of unused generation in reserve, and if only a fraction of this reserve was instructed to dispatch within 60 seconds of the initial loss it’s very likely that load shedding would have not occurred." My understanding was that having reserves available within 30-60s was pretty expensive, and that that would have been what was us…

Might be pumped water storage like "Electric Mountain" in North Wales (there's some in Scotland too, not sure what the total pumped storage on the grid is). They pump water to remove excess power from the grid and then run in reverse to generate. Their 0-100% is O(1minute) IIRC, actually on the website they say: >"Synchronised and spinning-in-air emergency load pick-up rate from standby: 0 to 1,320 MW in 12 seconds"…

There are two in Scotland: Cruachan (the "Hollow Mountain") and at Foyers with a new much larger scheme proposed for Coire Glas above the Great Glen.
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