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Large scale UK power cuts

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TheMotorcycleBoy
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Re: Large scale UK power cuts

#247657

Postby TheMotorcycleBoy » August 29th, 2019, 6:24 am

scotia wrote:Lightning strikes followed by a protection breaker being opened, then by an automatic reclosure when any arc has been quenched is fairly common - but it can surprise the unwary. Many years ago I was carrying out tests on a grid connected 20MW hydro turbine up a remote glen in mid winter. I had a young assistant, whom I was watching with an eagle eye. The tests were successfully completed, and I ensured that my equipment was disconnected from the turbine, which had been closed down. I then instructed my assistant to back up the logged data, and I now was sufficiently relaxed to chat to the plant operators, when there was a bang, and the lights went out. I screamed the name of my assistant, but barely had the echo died down when the lights came back on - it had been a lightning strike on the transmission line from the power station. My assistant often cast it up to me - "you thought I was to blame - you didn't trust me!". I should also add that the lightning strike had no effect on the trains in Scotland, or England!

Ha! It's always the next in lines fault!

dspp
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Re: Large scale UK power cuts

#250912

Postby dspp » September 11th, 2019, 8:38 am

"National Grid will accelerate plans for new blackout safeguards to avoid another energy system shock after more than a million homes were left without electricity last month.

The grid operator admitted after Britain’s biggest blackout in a decade that the energy system’s standards should be more resilient against the risk of unexpected power plant outages.

In a report for Ofgem, the industry regulator, it conceded that it would need to bring forward a programme to upgrade its safeguards, due by 2022, which could have helped to prevent the mass blackout on 9 August."


https://www.theguardian.com/business/20 ... eguards-uk

I haven't located the report itself yet.

regards, dspp

scotia
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Re: Large scale UK power cuts

#250939

Postby scotia » September 11th, 2019, 9:58 am

dspp wrote:"National Grid will accelerate plans for new blackout safeguards to avoid another energy system shock after more than a million homes were left without electricity last month.

The grid operator admitted after Britain’s biggest blackout in a decade that the energy system’s standards should be more resilient against the risk of unexpected power plant outages.

In a report for Ofgem, the industry regulator, it conceded that it would need to bring forward a programme to upgrade its safeguards, due by 2022, which could have helped to prevent the mass blackout on 9 August."


https://www.theguardian.com/business/20 ... eguards-uk

I haven't located the report itself yet.

regards, dspp

Is this a new report by the National Grid ?. I.E. is it an update on the Interim report of 9th August?
I'm on Ofgem's mailing list for their response to the National Grid's report - but I haven't received anything so far.

dspp
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Re: Large scale UK power cuts

#250950

Postby dspp » September 11th, 2019, 10:21 am

scotia wrote:
dspp wrote:"National Grid will accelerate plans for new blackout safeguards to avoid another energy system shock after more than a million homes were left without electricity last month......"

https://www.theguardian.com/business/20 ... eguards-uk

I haven't located the report itself yet.

regards, dspp

Is this a new report by the National Grid ?. I.E. is it an update on the Interim report of 9th August?
I'm on Ofgem's mailing list for their response to the National Grid's report - but I haven't received anything so far.


It reads as if something new has been released. However since it doesn't actually contain anything that we don't already know it could just be a journalist returning from holidays and struggling to fill his/her quota. It also contains the normal lobbying from battery companies who are often running marketing campaigns to influence things, and journos are often lazy & feed off of them. Bottom line = I am unsure and looking around to see if something new has been released.

regards, dspp

sunnyjoe
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Re: Large scale UK power cuts

#251000

Postby sunnyjoe » September 11th, 2019, 12:03 pm


scotia
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Re: Large scale UK power cuts

#251017

Postby scotia » September 11th, 2019, 12:30 pm

sunnyjoe wrote:The final report is available here
https://www.nationalgrideso.com/informa ... erator-eso

Thanks - I'm trying to digest it!

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Re: Large scale UK power cuts

#251068

Postby scotia » September 11th, 2019, 2:31 pm

scotia wrote:
sunnyjoe wrote:The final report is available here
https://www.nationalgrideso.com/informa ... erator-eso

Thanks - I'm trying to digest it!

Ok - it makes extremely interesting reading (for us geeks). Below is my summary of the more interesting parts (from my standpoint). My apologies if I have misunderstood any of the details.

So looking at the blame game - Hornsea Wind farm have already pleaded guilty and claim to have rectified their problem which caused a needless loss of generation.

But Little Barford certainly does not get a clean bill of health. They seem to be unsure why the steam turbine closed down, and the steam bypass which should have allowed the associated gas turbines to continue also appears not to have worked - and again they don't seem to know why. My guess is that it has never been tested.

Initially a substantial amount of embedded generation tripped on vector shift protection, followed slightly later with lots more embedded generation being tripped by rate-of-change of frequency protection. And there seems to have been an unexpected contribution of embedded generation tripping due to under-frequency at 49Hz. The Electricity Distributors (DNOs) have found it difficult to obtain the exact details of what caused each part of the embedded generation to trip - I quote:-
All DNOs have responded to this request and indicated a combined total of 462MW of embedded
generation was lost during the event. In providing their analysis some DNOs noted challenges in
obtaining the data due to the way it is collected or stored and without confirmation from generators,
DNOs were unable to determine whether a specific generator tripped due to RoCoF or Vector Shift.

Analysis has suggested that some parts of the system may have experienced a rate of change of frequency of 0.125Hz/s or above and/or a Vector shift exceeding 6 degrees. My personal opinion is that the current embedded generation protection has been over-sensitive.

The blame game on the trains looks like turning into a real scrap. The Electricity Distributors (DNOs) maintain that they did not disconnect any supplies to the rail network - but Network Rail appear to disagree. I quote
The DNOs confirmed that no track supplies were lost due to the DNO’s LFDD protection operation.
Through their investigation, Network Rail have stated that their supply disruption was likely to have
been caused by supply interruption from the DNO networks. Network Rail are to undertake key
discussions with the DNOs to explore further.

However, what is not disputed is that Class 700 and 717 trains incorrectly shut down on a frequency drop to 49Hz, and half of them required the attendance of a technician with a laptop to reset them.

scotia
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Re: Large scale UK power cuts

#251142

Postby scotia » September 11th, 2019, 6:10 pm

And after reading National Grid's report, I had another look at the Guardian's report.

Guardian:-The grid operator admitted after Britain’s biggest blackout in a decade that the energy system’s standards should be more resilient against the risk of unexpected power plant outages.
National Grid Report:-Recommended Action: Review the security standards (SQSS) to determine whether it would be
appropriate to provide for higher levels of resilience in the electricity system. This should be done in a
structured way to ensure a proper balancing risks and costs.

On this, National Grid is much more cagey - note the wording - "proper balancing risks and costs"

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Re: Large scale UK power cuts

#251326

Postby dspp » September 12th, 2019, 10:46 am

I'm just reading through the report.

They lost 1.9 GW of generation in total (1,878MW to be precise) compared with the backup provision of 1 GW.

Ouch.

You can see why senior people were choosing their words exceedingly carefully in the public interviews in the immediate aftermath. I expect that will continue to be the case.

regards, dspp

scotia
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Re: Large scale UK power cuts

#251352

Postby scotia » September 12th, 2019, 12:30 pm

dspp wrote:I'm just reading through the report.
They lost 1.9 GW of generation in total (1,878MW to be precise) compared with the backup provision of 1 GW.
Ouch.
You can see why senior people were choosing their words exceedingly carefully in the public interviews in the immediate aftermath. I expect that will continue to be the case.
regards, dspp

Yes - but it doesn't seem to be bouncing National Grid into planning for such major outages - which would involve larger costs, ultimately to consumers.
They are "reviewing" the current 3 year plan to de-sensitise the protection on embedded generation - to me it was quite incredible that about 500MW of it simply tripped out on small transients that may have been reasonably predicted.
From experience, I know it is difficult to test generation systems under grid fault conditions - so perhaps it was not surprising that unexpected incidents occurred at Hornsea and Little Barford. Hornsea are convinced they know the reason and have corrected it. But the problem at Little Barford appears to be, as yet, unresolved. Could this be an endemic problem at other Gas fired power stations - or is it specific to Little Barford? In particular I'm thinking about the apparent failure of the steam bypass system.
Returning to the effects on consumers - as far as National Grid is concerned its load shedding worked correctly and should have caused very little inconvenience. The major problems on the railways seem to be of their own making.
So I think National Grid may be largely exonerated when Ofgem make their report. Although I still think that they were rather lax in the management of embedded generation.

dspp
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Re: Large scale UK power cuts

#251373

Postby dspp » September 12th, 2019, 1:40 pm

scotia wrote:
dspp wrote:I'm just reading through the report.
They lost 1.9 GW of generation in total (1,878MW to be precise) compared with the backup provision of 1 GW.
Ouch.
You can see why senior people were choosing their words exceedingly carefully in the public interviews in the immediate aftermath. I expect that will continue to be the case.
regards, dspp

Yes - but it doesn't seem to be bouncing National Grid into planning for such major outages - which would involve larger costs, ultimately to consumers.
They are "reviewing" the current 3 year plan to de-sensitise the protection on embedded generation - to me it was quite incredible that about 500MW of it simply tripped out on small transients that may have been reasonably predicted.
From experience, I know it is difficult to test generation systems under grid fault conditions - so perhaps it was not surprising that unexpected incidents occurred at Hornsea and Little Barford. Hornsea are convinced they know the reason and have corrected it. But the problem at Little Barford appears to be, as yet, unresolved. Could this be an endemic problem at other Gas fired power stations - or is it specific to Little Barford? In particular I'm thinking about the apparent failure of the steam bypass system.
Returning to the effects on consumers - as far as National Grid is concerned its load shedding worked correctly and should have caused very little inconvenience. The major problems on the railways seem to be of their own making.
So I think National Grid may be largely exonerated when Ofgem make their report. Although I still think that they were rather lax in the management of embedded generation.


I am still wading through the detail of the report, but:

1. Of course they (NG) will resist being bounced. To be bounced would be an admission they had overlooked something. Er, like that 500 MW of embedded .... So I agree with you on that as it was entirely foreseeable imho. I don't think NG should be entirely exonerated, and the reason I think that is because of this issue.

2. I tend to agree that the Hornsea and Litttle Barford were (so far in my reading) latent faults, i.e. ones that were a priori undetected. Whether they should have been detected in advance I am less certain of. Whether they are corrected now, I am even less certain of. Whether other power plants have similar latent faults, well I am quite sure they do (that last is based on my having been a power plant operator, albeit in the MW class, not the GW class). What are the chances of two latent faults combining in these circumstances. Hmmmm...... However I would agree that this is not an item to lay at NG's door.

3. Regarding the sensitivity of the embedded protections I have nil charitable thoughts towards the NG ESO and/or the DNOs on this matter. The amount of grief these people have caused the embedded generators is unbelievable. They have over the decades deliberately set standards criteria that are so tight that embedded are very frequently tripped off the network because the network itself is far more unstable than the NG ESO and/or DNOs are prepared to admit. So for them to now wring their hands and complain that the embeddeds are not riding through gets zero sympathy from me. They have no idea (or sympathy for) of the grief they have caused the embedded generators over the years, and so I have very little sympathy for them in return. As far as I am concerned if they want embedded to be supportive (in every respect) then they can pay for it. This is an item to be laid at all three doors: Ofgem + NG ESO + DNOs.

4. Regarding trains etc, full agree.

5. Regarding loadshedding. Yes, did exactly as it was supposed to.

6. Regarding costs if you look at this https://www.ofgem.gov.uk/data-portal/br ... icity-bill you can see that 23% is network costs, and 20% is environmental & social costs. When I look at https://www.ofgem.gov.uk/environmental-programmes I can see that all these items are nothing to do with the backup power. So the backup power is contained in the 23%. But when I look for e.g. https://www.ofgem.gov.uk/key-term-expla ... work-costs it doesn't help me identify what % of the 23% is backup power (etc) costs, presumably at the 1GW level, i.e. I cannot guesstimate what would be the £££ implication for the average consumer of (say) doubling it to 2GW of typical backup. Does anyone know how/where to drill into this ?

regards, dspp


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