UK August 2019 Blackout

[mbrooke]

Sounds like their was massive widespread under frequency load shedding. Anyone know what happened or why? Two generators (units) should not cause this unless they mean two complete power station.


https://www.telegraph.co.uk/news/20...cross-country-london-goes-dark-national-grid/


https://twitter.com/ng_eso

 

[broadgage]

By "generators" yes they mean power stations. Two power stations failed within a couple of minutes, one was a combined cycle natural gas burning power plant, and the other a large off shore wind farm. I am not aware of any mechanism that would cause simultaneous failures of numerous wind turbines and therefore I surmise that the fault was in cables, or switchgear common to the whole wind farm.

The national grid are required to be prepared for the largest foreseeable SINGLE loss of generating capacity, but in the event of TWO such losses then power cuts are likely.

The national grid have a legal duty to maintain the frequency between 49.5 cycles and 50.5 cycles, and can be fined for failing in this duty. They might be prosecuted for yesterdays failure.

If the frequency drops below 49.5 cycles, then OCGT plant starts automatically, and if the frequency continues to fall then frequency relays disconnect a proportion of the load so as to prevent a total collapse.
Yesterday about 5% of the total UK load was disconnected.

These events are rare, the last one was in 2008 IIRC.

 

[zbang]

The national grid have a legal duty to maintain the frequency between 49.5 cycles and 50.5 cycles, and can be fined for failing in this duty.

That wide a tolerance?

There's some actual data on https://extranet.nationalgrid.com/RealTime but the freq graph is only 60 minutes.

Also http://grid.iamkate.com/

 

[broadgage]

Yes, the legal limit for UK grid frequency is from 49.5 cycles up to 50.5 cycles.
They try, so far as possible, to keep within closer operational limits of 49.8 cycles to 50.2 cycles. Excursions outside of these tighter operational limits are relatively rare, and you would have to watch the chart for a long time to see one.

In addition to the "last 60 minutes" chart linked to above, the site below gives a virtually real time display of grid frequency.
http://www.dynamicdemand.co.uk/grid.htm

 

[mbrooke]

By "generators" yes they mean power stations. Two power stations failed within a couple of minutes, one was a combined cycle natural gas burning power plant, and the other a large off shore wind farm. I am not aware of any mechanism that would cause simultaneous failures of numerous wind turbines and therefore I surmise that the fault was in cables, or switchgear common to the whole wind farm.

The national grid are required to be prepared for the largest foreseeable SINGLE loss of generating capacity, but in the event of TWO such losses then power cuts are likely.

The national grid have a legal duty to maintain the frequency between 49.5 cycles and 50.5 cycles, and can be fined for failing in this duty. They might be prosecuted for yesterdays failure.

If the frequency drops below 49.5 cycles, then OCGT plant starts automatically, and if the frequency continues to fall then frequency relays disconnect a proportion of the load so as to prevent a total collapse.
Yesterday about 5% of the total UK load was disconnected.

These events are rare, the last one was in 2008 IIRC.

I'm guessing the wind turbines failed from a falling frequency they could not pickup, or little inertia from during a fault else where.

Do you know why the first power station failed?

 

[Besoeker3]

Yes, the legal limit for UK grid frequency is from 49.5 cycles up to 50.5 cycles.
They try, so far as possible, to keep within closer operational limits of 49.8 cycles to 50.2 cycles. Excursions outside of these tighter operational limits are relatively rare, and you would have to watch the chart for a long time to see one.

In addition to the "last 60 minutes" chart linked to above, the site below gives a virtually real time display of grid frequency.
http://www.dynamicdemand.co.uk/grid.htm

Another link:
https://www.gridwatch.templar.co.uk/

 

[Tony S]

Yes, the legal limit for UK grid frequency is from 49.5 cycles up to 50.5 cycles.

They are the Hz “legal” limits, the operational band is wider. Before a total shut down of the national grid occurs load shedding kicks in, who’s going to worry about a few shepherds?

Another time and another place, we suddenly switched a 12 MVA load off line (emergency stop). The grid frequency went high because the load vanished.

 

[mbrooke]

They are the Hz “legal” limits, the operational band is wider. Before a total shut down of the national grid occurs load shedding kicks in, who’s going to worry about a few shepherds?

Another time and another place, we suddenly switched a 12 MVA load off line (emergency stop). The grid frequency went high because the load vanished.

60Hz can be a good thing

 

[Tony S]

60Hz can be a good thing

It didn’t go that high.

Beats me why you colonials settled on such a weird set of disjointed voltages and frequency :?

 

[mbrooke]

It didn’t go that high.

Beats me why you colonials settled on such a weird set of disjointed voltages and frequency :?

The voltages are all over the place, I'll give you that. :happyyes:

 

[readydave8]

It didn’t go that high.

Beats me why you colonials settled on such a weird set of disjointed voltages and frequency :?

Just how it happened to work out back when we invented electricity:angel:

(If I saw a "cover my head and duck" emoji I'd include it)

 

[junkhound]

It didn’t go that high.

Beats me why you colonials settled on such a weird set of disjointed voltages and frequency :?

The aliens that were advising Tesla and Westinghouse had six fingered hands so 60Hz. And, The 25 Hz and 50 Hz flicker from incandescent lights bothered the aliens - the aliens did not think even Tesla was ready for LED and SiC inverter technology yet.

 

[mbrooke]

What happened according to the media:

https://www.youtube.com/watch?v=eynO_SMgcag

 

[Besoeker3]

What happened according to the media:

https://www.youtube.com/watch?v=eynO_SMgcag

I read that about one million people were affected. UK population is about sixty million.

 

[mbrooke]

I read that about one million people were affected. UK population is about sixty million.

I think it was a few levels of load shedding. Seriously you need more nuclear and high inertia plants. Along with reserve capacity which is technically easy with nuclear.

 

[Besoeker3]

I think it was a few levels of load shedding. Seriously you need more nuclear and high inertia plants. Along with reserve capacity which is technically easy with nuclear.

Such events are very infrequent here and this was a very unusual coincidence.

I cannot recall/have not been subjected to one single such incidence at home or work in several decades.
Currently, grid frequency is 50.016 Hz

 

[mbrooke]

Such events are very infrequent here and this was a very unusual coincidence.

I cannot recall/have not been subjected to one single such incidence at home or work in several decades.

My best guess is they were already running near limits. A bus fault or failed breaker cleared multiple generators instead of just one. The wind farm then saw a slight dip in frequency and it being it a wind farm just shutdown providing no real "support" to the grid simply ridding down with the lowering frequency.

Any idea if the frequency went up or down between the first combined cycle plant trip and the wind farm trip?

 

[mbrooke]

Such events are very infrequent here and this was a very unusual coincidence.

I cannot recall/have not been subjected to one single such incidence at home or work in several decades.
Currently, grid frequency is 50.016 Hz

Here is the substation right next to the Little Bradford units, it looks like a single breaker double busbar station, with the south bus sectionalized.

A breaker failure or bus fault would remove 1/3 of the elements, a failed bus coupler or busbar sensationalizing breaker would remove 2/3 of them. That would easily explain the removal of two generators along with altering the power flows in a now critical state.


And hey, guess what mods, I can't post pictures because it won't "resize". :roll::roll: Can someone fix this?

 

[Tony S]

Normally the “National Grid” is robust enough to cope with the occasional blip.

The only time I recall “load shedding” was during a coal miners strike. Load shedding would involve cutting the supply to areas, the power company would inform customers of the time of the cuts.

I spent many miserable hours monitoring our company’s intake substation load. Starting and shutting down sections in turn to keep the load under 8MVA normally it would be around 17MVA.
At least at home I had a 7kW generator so the cuts didn’t bother me that much. The downside was the neighbours wanting to know why we still had power.

 

[mbrooke]

Normally the “National Grid” is robust enough to cope with the occasional blip.

The only time I recall “load shedding” was during a coal miners strike. Load shedding would involve cutting the supply to areas, the power company would inform customers of the time of the cuts.

I spent many miserable hours monitoring our company’s intake substation load. Starting and shutting down sections in turn to keep the load under 8MVA normally it would be around 17MVA.
At least at home I had a 7kW generator so the cuts didn’t bother me that much. The downside was the neighbours wanting to know why we still had power.

check this out:




https://www.tdworld.com/outage-management/uk-blackout-one-lightning-strike-sparks-cascade-probes