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What Happened in the UK Blackouts?

mitchoneill.com

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Re: What Happened in the UK Blackouts?

#61

Post by rcxdude »

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?

The grid frequency itself doesn't matter much as far as consumers are concerned, the deviations mentioned in this article would not cause any problems for a home user directly (or even generators, but as mentioned below if it is too far out of range generators start to need to cut out) but it is a far better indicator of the general balance of supply and demand of power in the grid than any other metric, because it can be measured very precisely, isn't subject to local effects like voltage, and correlates well with the state of the generators.

One quirk of synchronous generators is you can think of the whole grid like all of the generators in it are geared together. If demand rises, the torque on the generators starts to increase and if the power plants don't feed more mechanical power in then they will start to slow down in unison. Likewise their speed will increase as the demand drops. So the frequency is the main indicator of the health of the grid and so the grid operators will monitor it closely.

Re: What Happened in the UK Blackouts?

#62

Post by circular_logic »

eDISCO wrote: post #10

Most traditional generators (think CCGT, nuclear, hydro) run in synchronous mode. Which means the generators spins with rpm proportional/equal to the network frequency. For 50Hz that would be 3000rpm. When the total electricity demand exceeds the supply, the kinetic energy of spinning generators is converted to electricity which slows down the generator rpm, which reduces the frequency. All synchronous generators on…

That makes me wonder, if you were standing next to these turbines would you be able to here them slow down?

Re: What Happened in the UK Blackouts?

#63

Post by std_throwaway »

londons_explore wrote: post #16

It's notable that this report is completely consistent so far with the way I would design a cyber attack to take out a countries power grid. > The causes provided by RWE for the initiation of the trip of Little Barford steam turbine (ST1C) was due to discrepancies on three independent safety critical speed measurement signals to the generator control system. A cyber attack would most likely, rather than directly take…

An even more stealth method is to make the system work perfectly if everything is running fine. Like correctly reporting net frequency in the range 49-51 Hz but reporting false values when outside of that range. That way there will be no detectable errors until everything starts behaving erratically.

The best way for a society to prepare is to have a few small incidents that put the safety systems to the test on a regular basis.

Re: What Happened in the UK Blackouts?

#64

Post by wongarsu »

guerby wrote: post #47
mitchoneill1 wrote: post #28

Earlier quoted context omitted.

Hey! (author of the article here). I'm not happy with how I phrased this with the 4GW of capacity -- and while I suspect generation could have increased by hundreds of MW within 60 seconds I may be wrong. I've updated how I've phrased it in the blog to hopefully give a bit more clarity to my position. I don't meant to suggest that plants could ramp full within 60 seconds, it's that 4GW means there's a bunch of headro…

I assume battery based grid power stations like the Tesla one in Australia are amongst the best in class to help in this kind of crisis situation? Compared to the gaz turbine the system it is simpler (no mehanical/heat/fluid parts) and depending on design will likely never be completely off since made of dozens or hundreds of independant equipement (batteries and inverters). Thanks for the article and comment!

Pretty much the only plants you can get to full power in such a short notice are battery or hydroelectric. Even pumped-storage hydro typically takes 10-30 seconds to full power because of inertia. Batteries are much more expensive, but as close to instant as it gets.

Re: What Happened in the UK Blackouts?

#65

Post by sergioj97 »

Zenst wrote: post #42
mytailorisrich wrote: post #31

Earlier quoted context omitted.

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?

"Would you not prioritise an airport, a hospital, the railway, over residential areas?" Yes and they do. As mentioned, things get added to the grid all the time, case of the airport was that it was not on a priority list. Yes that is an oversight, but who's fault and accountability we do not know. The onus would of been in the airport to inform the power distribution and if that failed to happen then the airport woul…

I'm pretty sure there is a lot of people who is interested to know if this is someone's fault, and I don't think it has anything to do with how media covers this issues. I think it's a good thing, in fact.

This failure may be within acceptable parameters and it may be simply meaningless to try to find someone truly responsible for it. But you seem to be unreasonably reluctant to believe that maybe it's not.

I understand that it's interesting to analyze what happened from a more technical perspective, but of course a proper investigation has to be conducted to find the responsible if there happens to be one (or more).

Re: What Happened in the UK Blackouts?

#66

Post by HenryBemis »

londons_explore wrote: post #16

It's notable that this report is completely consistent so far with the way I would design a cyber attack to take out a countries power grid. > The causes provided by RWE for the initiation of the trip of Little Barford steam turbine (ST1C) was due to discrepancies on three independent safety critical speed measurement signals to the generator control system. A cyber attack would most likely, rather than directly take…

> A cyber attack would most likely..

When I was discussing the two interruptions (one on the 9nth and a smaller one on the 24th) with friends, I suggested that this could have been an attempt to map out UK's infrastructure/SCADAs, and they thought that my sandwich had too much consiracy sauce in it.

Remembering how Stuxnet interefered with Iran's nuclear centrifuges, this could very well be something similar. Just scratch it a bit, where it matters most, and let it sink on its own. No point blasting a huge hole in it.

Re: What Happened in the UK Blackouts?

#67

Post by fanf2 »

circular_logic wrote: post #62
eDISCO wrote: post #10

Most traditional generators (think CCGT, nuclear, hydro) run in synchronous mode. Which means the generators spins with rpm proportional/equal to the network frequency. For 50Hz that would be 3000rpm. When the total electricity demand exceeds the supply, the kinetic energy of spinning generators is converted to electricity which slows down the generator rpm, which reduces the frequency. All synchronous generators on…

That makes me wonder, if you were standing next to these turbines would you be able to here them slow down?

The change in pitch from 50Hz to 48.8Hz was 0.4 semitones.

12 * ln 50 / ln 2 = 67.7

12 * ln 48.8 / ln 2 = 67.3

Re: What Happened in the UK Blackouts?

#68

Post by buckminster »

aurbano wrote: post #41

It actually sounds like this was really useful though, as a lot of the systems involved will be improved in the future. I'm not sure if the grid is already doing this, but they should trigger failures randomly, including Low Frequency Demand Disconnection schemes from time to time to ensure that all downstream systems are also ready (like the hospital someone mentioned that had an issue with the backup generator, or…

The whole point of sophisticated grid management is to save us money by reducing the total generating capacity needed for a reliable supply. If this were to impose massive costs on the rest of society in the form of planned blackouts then what would be the point? Why not invest in a little extra capacity?

Re: What Happened in the UK Blackouts?

#69

Post by mantap »

HenryBemis wrote: post #66
londons_explore wrote: post #16

It's notable that this report is completely consistent so far with the way I would design a cyber attack to take out a countries power grid. > The causes provided by RWE for the initiation of the trip of Little Barford steam turbine (ST1C) was due to discrepancies on three independent safety critical speed measurement signals to the generator control system. A cyber attack would most likely, rather than directly take…

> A cyber attack would most likely.. When I was discussing the two interruptions (one on the 9nth and a smaller one on the 24th) with friends, I suggested that this could have been an attempt to map out UK's infrastructure/SCADAs, and they thought that my sandwich had too much consiracy sauce in it. Remembering how Stuxnet interefered with Iran's nuclear centrifuges, this could very well be something similar. Just sc…

If that was the intention it backfired because it highlighted several problems to National Grid that they weren't aware of before.

Re: What Happened in the UK Blackouts?

#70

Post by xyk2 »

aurbano wrote: post #41

It actually sounds like this was really useful though, as a lot of the systems involved will be improved in the future. I'm not sure if the grid is already doing this, but they should trigger failures randomly, including Low Frequency Demand Disconnection schemes from time to time to ensure that all downstream systems are also ready (like the hospital someone mentioned that had an issue with the backup generator, or…

That would be like AWS telling all customers that their services would randomly go offline to test disaster response. The responsibility for blackout testing should be at the client level, at each hospital, train station etc similar to fire drills.
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