UK power cut
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What happened back in August when there were power cuts?
The National Grid's report says:
"Two almost simultaneous unexpected power losses at Hornsea and Little Barford occurred independently of one another but each coincident with a lightning strike. This caused a significant loss of power from the grid and represented an event beyond the standards to which the system is normally secured.
"The scale of generation loss exceeded the normal automatic protection systems and reserve holdings and resulted in automatic disconnection of 1GW of demand in order to preserve the system (and allow supply to continue for the remaining 28GW of demand). These systems worked in line with their design to protect as much electricity demand as possible. However, there was significant knock-on disruption from the event and to other critical infrastructure."
So there you have it!
By Ian Westbrook
BBC Business reporter
BBC Business News
An interim report on the major powercut earlier this month has found that it was caused by a chain of events, set off by a lightning strike.
Thousands of homes in the North East experienced the black out with Newcastle Airport and the railways also impacted.Copyright: PA MEDIA
BBC Radio 4
Commenting on the impact of the recent power cut on the UK's railways, Sir John Armitt, said: "The rolling stock having lost power was then not immediately able to reboot itself. So engineers had to be sent out to reboot the trains.
"That is something which clearly you would look at in the control systems of those trains, and say that's clearly not ideal - what needs to be done within the control systems of the trains to enable them to reboot".
"That's a complex issue for the rolling stock manufacturers and Network Rail."
Sir John said it raises questions about "what are the most critical elements of our infrastructure across this country and which elements do you turn off first because some you will avoid turning off if you possibly can".
"Have we got that order of priority right? And so why was it the railways that went down as opposed to those of us living at home not losing some of our electricity?"
BBC Radio 4
More from Sir John Armitt, chairman of the National Infrastructure Committee on National Grid's report into the blackout on 9 August.
He said we now needed to "understand in a lot more detail and learn from this and look at the resilience of the whole network and make sure we can take action across the different elements of our electricity supply to minimise the effect of something like this happening again".
It was a series of events, not necessarily connected, he said: "But that happens once every 10 years, according to National Grid, and given our reliance on energy these days across so many different elements of our infrastructure, whether its our water supply, or massive data systems we have now, our transport networks, we as the National Infrastructure Commission over the next nine months are doing a full resilience evaluation across all these different types of infrastructure.
"The important thing is this a great case study in a way. It is a very unfortunate one, a lot of people were impacted by it but it is something which everyone involved can learn from."
In its report into what caused the blackout on 9 August, National Grid says:
- Two almost simultaneous unexpected power losses at Hornsea and Little Barford occurred independently of one another but each associated with the lightning strike. As generation would not be expected to trip off or de-load in response to a lightning strike, this appears to represent an extremely rare and unexpected event.
- This was one of many lightning strikes that hit the electricity grid on the day, but this was the only one to have a significant impact; lightning strikes are routinely managed as part of normal system operations.
- The Distribution Network Operators quickly restored supplies within 31 minutes once the system was returned to a stable position.
- Several critical loads were affected for a number of hours by the action of their own systems, in particularly rail services.
National Grid will submit a final report to energy regulator Ofgem on 6 September.
Ofgem, the energy regulator, said has launched an investigation into a blackout that hit homes, businesses and infrastructure in England and Wales on 9 August, following a report by National GridQuote Message: The power cuts of Friday 9 August caused interruptions to consumers’ energy and significant disruption to commuters. It’s important that the industry takes all possible steps to prevent this happening again. Having now received National Grid ESO’s interim report, we believe there are still areas where we need to use our statutory powers to investigate these outages. This will ensure the industry learns the relevant lessons and to clearly establish whether any firm breached their obligations to deliver secure power supplies to consumers.” from Jonathan Brearley executive director of systems and networks, Ofgem
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National Grid says that lighting for partly to blame for a blackout in England and Wales on Friday 9 August.
In a report it said that there are a lighting strike on a transmission circuit north of London but the protection systems operated and cleared it quickly.
However, it said that "immediately following the lightning strike and within seconds of each other" both Hornsea off-shore windfarm and Little Barford gas power station reduced their energy supply to the grid.
Following the publication of National Grid's report into the recent blackout, Sir John Armitt, chairman of the National Infrastructure Commission, says: "That's what we have at the moment is a sequence of events. We don't know to what extent they are connected or whether it was a series of coincidental events.
"The system did recover, backup power did come in but there was a point at which it was necessary to reduce the total amount of power available across the networks by 5% which in turn then led to a loss of power in certain parts of the country."
The government is currently investigating whether procedures followed by National Grid are fit for purpose following last week's huge power cuts across England and Wales.
The Guardian yesterday reported that National Grid had experienced three “near-misses” in as many months and was aware of the growing potential for blackouts.
But National Grid disagrees...Quote Message: Contrary to media reports there have been no near misses nor early warning signs of incidents similar to last Friday’s power cuts. This was a highly unusual event, without precedent in the past 10 years. We work with Ofgem to set the agreed limits of frequency of electricity output to keep the whole system safe and the lights on. All the time until Friday’s events, the system has remained within safe limits. We are conducting a thorough internal investigation and will report our interim findings in detail to Ofgem by the end of this week. We can and must learn lessons from Friday’s events – however rare their occurrence – as National Grid and as an energy industry." from Spokesman National Grid
The National Grid's operations director explains why nearly one million people lost power on Friday.
By Winnie Agbonlahor
BBC News, London
By Joseph Lee