Hypothesies must not be multiplied without necessity.

However, I thought it strange that at least one newspaper sought to point out that it was not a cyber attack. A cyber attack never even struck me as I drove home with the local traffic lights and speed cameras knocked out. I initially suspected a HT line down somewhere out in the bundu due to the thunderstorm and high winds.

I'm sure that those who know about system stability etc. will be on the case.


My question, which no one seem to be talking about, is why the outage caused such problems on the railways. The BBC reported that specialist engineers were being sent out to stranded trains to get them going again. Surely a driver can start a train after a power cut?

According to the BBC (https://www.bbc.co.uk/news/uk-49302996) the problems were caused by the Little Barford gas-fired power station "failing", closely followed by the  Hornsea offshore wind farm disconnecting from the grid. The national grid responded (apparently automatically) by load shedding some customers to restore stability.


I might hazard a guess that wind farm disconnecting might have been triggered by the grid instability (low frequency, possibly low voltage) caused by the gas station failing.


It would be interesting to know how the grid "decided" which parts of the network to shed load from - in some ways the choices made (e.g. rail traction supplies) might not have been optimal from the bigger picture point of view.


Maybe time to question too whether automatically disconnecting (renewable) generators when the grid is short of generating capacity is necessarily the correct approach.


I wonder how things might have been different if everyone had had smart meters installed - in theory then the grid could have responded by directing , via the smart meter network, low priority appliances to shut down - so spreading the load shedding almost invisibly across the whole network possibly avoiding the need for complete power cuts for anyone.


  - Andy.

Re Smart Meters, I can see that this is where we are heading but I suggest that it will be may years before we have the technology installed to selectively disconnect certain domestic consumers in the even of load shedding  and even longer before the grid can selectively disconnect some loads within domestic premises.

I would need a big discount on my tariff before i signed up to that one!

I noticed on the southwest news on ITV last nite that around 30 000 customers in south Devon were disconnected at the time of the grid problems was that coincidence it's hard to see how a problem at little barford could cause supply loss so many miles away. We had no problems here in Weymouth  thank goodness.

I have talked about this before on the forum and elsewhere. If one looks at the grid status at the moment it is about 27% wind and 24% gas turbines. The wind is gusty and so the peak capacity from it may be 50%, as there is no particular mechanism to control the output from a synchronous wind turbine.  This puts a huge problem on the grid and stability is simply not possible, leading to automatic shutdowns. I have a suggestion that the gas unit may have become unable to follow the rapid frequency changes, leading to massive reactive power surges and so shut down, and then the lack of availability and low frequency led to the power shedding and wind shutdown. We shall see what is said but blaming National Grid is certainly not the answer, I'm sure they do not want out of control wind sources connected at all. The lesson may well be that wind sources are too unstable to be directly connected to the grid.

No we mustn't blame the grid engineers I'm sure they reacted in what they thought was the best way to what was probably a scary situation and this is an exceptional event I've seen the frequency fall from just shy of 50 cycles downt to 49.8  cycles very rapidly several times and no power cuts or load shedding so what went wrong must of been unusually sever  I'm sure you will agree with me

"The lesson may well be that wind sources are too unstable to be directly connected to the grid."

Or that more battery storage is needed each time a large wind array is added and this needs to be factored into the costs.

That idea is basically unworkable Harry. Such a battery would need a huge capacity to be much use, and it would be cycled quite rapidly so life might be poor. A battery with a capacity of say 100GWh would have an immense energy density and be extremely dangerous. Some battery capacity might help to smooth the wind output, but again would be cycled quite quickly. A very large flywheel might be good but again would be rather risky. Connecting the turbine to the grid with a pile of electronics would improve control, but add a considerable degree of cost, which would make the wind supply less attractive.

In Mid Devon, Okehampton, the power went off and on again almost immediately at the precise time

of the national outage.

The local wind farm blades were not turning in the high winds as I drove home.

Is this the risk with wind power; that high winds demand a sudden loss of supply to protect

the turbines and blades?


Terence.