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Coming shortage of UK generating capacity?
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Potemkin Villager



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PostPosted: Sat Sep 24, 2016 1:53 pm    Post subject: Reply with quote

adam2 wrote:


Demand has fallen in the last few years but this is a very recent phenomena.

Demand is still rising in London and the south east, despite falling nationally, and some major upgrades are underway, with others planned.


Does this mean that the anticipated automatic disconnections when supply is unable to meet demand will occur only in London and the south east?
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adam2
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PostPosted: Sat Sep 24, 2016 1:59 pm    Post subject: Reply with quote

No, AFAIK any planned rota disconnections will be planned so as to spread the burden as fairly as possible.
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PostPosted: Sun Sep 25, 2016 1:33 am    Post subject: Reply with quote

adam2 wrote:
No, AFAIK any planned rota disconnections will be planned so as to spread the burden as fairly as possible.

How do they define what is fair and who makes those decisions?
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adam2
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PostPosted: Sun Sep 25, 2016 9:58 am    Post subject: Reply with quote

For planned or rota cuts, a preplanned rota is used that is designed to be be as fair as possible.
No individual decisions are made as to what is fair.

The total UK load is divided into 18 "load groups" each one of which is identified by a letter of the alphabet starting with "A" The letters O and I are not used lest they be confused with numerals 0, and 1. the letter F is not used for another reason.

Each of the 18 load groups contains an approximately equal amount of load, about one eighteenth of the national total. The physical area occupied by each load group varies a great deal, so as to ensure that each group contains about the same amount of load.
In an urban district, if say load group B if cut off, then places in other load groups that are still on will normally be in walking distance.
So far as is possible, large or important roads have each side of the road in different load groups, this does not apply to smaller roads, or indeed to ALL main roads.
In other cases, high streets have most of the road in one load group, but premises on corners, and street lights on corners are in a different load group.

Each customer has already been allocated a load group. This can not be altered by the customer and is most unlikely to be altered for any other reason.
And nothing would be gained by any attempt to alter ones load group since the rota is carefully planned to treat each load group equally.

It would be well to know in what load group you are, this is normally on your electricity bill.
Many people would find it useful to know in what load group their employers are, and also the load group of local shops, take away food outlets and public houses.

Maps of load groups will be published in local newspapers and on line.
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Last edited by adam2 on Sun Sep 25, 2016 1:10 pm; edited 1 time in total
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adam2
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PostPosted: Sun Sep 25, 2016 1:09 pm    Post subject: Power cut rota Reply with quote

As already described, the load is divided into 18 approximately equal load groups.

If rota cuts are required, a PRE-PLANNED rota will be put into operation. This has been most carefully planned so as to treat all load groups fairly.

Half of the load groups will have power cuts concentrated on Monday, Tuesday and Wednesday, with the other half having cuts on Thursday, Friday, and Saturday. This position will be reversed in the following week so as to ensure fairness.

Of the 9 load groups at risk of power cuts on a Monday, Tuesday or Wednesday, 3 of those load groups will be at highest risk on Monday, 3 on Tuesday, and 3 on Wednesday, again to ensure fairness this will be altered on alternate weeks.

Each day will be divided into 8 periods each of 3 hours with the start times as follows
00-30
03-30
06-30
09-30
12-30
15-30
18-30
21-30

On a high risk day, a customer would be liable to power cuts for 3 or 4 periods each of 3 hours.
For example a particular customer might be off from
06-30 until 09-30, and then from 12-30 until 15-30 and again from 18-30 until 21-30.
The next day that the same customer was at high risk of disconnection, these hours would be reversed to 09-30 until 12-30 and 15-30 until 18-30, plus a lesser risk either from 03-30 until 06-30 OR from 21-30 until 00-30 the following morning.
This alternation means that each load group not only gets the same number of disconnections but that the different hours of disconnection are fairly spread.
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PostPosted: Sun Sep 25, 2016 6:10 pm    Post subject: Re: Power cut rota Reply with quote

adam2 wrote:
As already described, the load is divided into 18 approximately equal load groups.

If rota cuts are required, a PRE-PLANNED rota will be put into operation. This has been most carefully planned so as to treat all load groups fairly.

Half of the load groups will have power cuts concentrated on Monday, Tuesday and Wednesday, with the other half having cuts on Thursday, Friday, and Saturday. This position will be reversed in the following week so as to ensure fairness.

Of the 9 load groups at risk of power cuts on a Monday, Tuesday or Wednesday, 3 of those load groups will be at highest risk on Monday, 3 on Tuesday, and 3 on Wednesday, again to ensure fairness this will be altered on alternate weeks.

Each day will be divided into 8 periods each of 3 hours with the start times as follows
00-30
03-30
06-30
09-30
12-30
15-30
18-30
21-30

On a high risk day, a customer would be liable to power cuts for 3 or 4 periods each of 3 hours.
For example a particular customer might be off from
06-30 until 09-30, and then from 12-30 until 15-30 and again from 18-30 until 21-30.
The next day that the same customer was at high risk of disconnection, these hours would be reversed to 09-30 until 12-30 and 15-30 until 18-30, plus a lesser risk either from 03-30 until 06-30 OR from 21-30 until 00-30 the following morning.
This alternation means that each load group not only gets the same number of disconnections but that the different hours of disconnection are fairly spread.

Why would there be any cutoffs in the off peak hours? Say between 15-30 and 06-30?
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adam2
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PostPosted: Sun Sep 25, 2016 8:09 pm    Post subject: Reply with quote

Under the presently foreseen circumstances, rota power cuts outside of the peak hours are most unlikely.
We appear to have ample generating capacity to meet the off peak load, and can probably meet even the peak load most of the time.

Doubt remain about the peaks under adverse conditions, perhaps the 10 or 20 coldest evenings of the year.

The preplanned rota is however an all purpose tool that has been drawn up to cater for even extreme circumstances.

So in practice under the PRESENTLY FORESEEN circumstances only those parts of the rota that refer to the 15-30 until 18-30 slot and to the 18-30 until 21-30 slot are likely to be applicable.
Rota cuts in the morning peak are a possibility, but a fairly remote possibility at present.

Or of course TPTB might draw up a different rota covering only the peaks, but for reasons of practicality this would be based on the present load groups, and would be arranged such that every load group was fairly treated.
One example might be to declare that rota cuts are only likely in the evening peak from say 16-30 until 19-30.

Firstly, draw up a list of dates when the supply might prove inadequate, this could be every working day in December, January, and February.
Excluding weekends, public holidays, and the nominally working days around the holiday season when many firms are closed.

Publish this list of dates, and declare that on
day one------A is at high risk
day two------B is at high risk
day three----C is at high risk
day four------D is at high risk

And so on, with the list repeating after 18 working days.
Each load group would thus be at high risk of disconnection on only about 3 evenings per winter.
If on any evening, it was required to disconnect TWO load groups, then the next load group, considered alphabetically would also be cut off.
For example on day 5, load group E would be cut off first, and if this did not shed enough load, group G would be cut off also. (no group F remember)
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cubes



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PostPosted: Sun Sep 25, 2016 8:31 pm    Post subject: Reply with quote

Interesting stuff.
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clv101
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PostPosted: Sun Sep 25, 2016 8:56 pm    Post subject: Reply with quote

Yea, thanks for this Adam2, I wasn't aware of this detail... Load group F?

Quote:
Demand is still rising in London and the south east, despite falling nationally, and some major upgrades are underway, with others planned.
That's interesting, where can I find regional demand data?
The decline since 2005 is pretty big, some 46TWh per year, with London and SE increasing, the falls elsewhere must be big!
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adam2
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PostPosted: Sun Sep 25, 2016 9:12 pm    Post subject: Reply with quote

I am not aware of any source for region specific load data.
BUT, UKPN, formerly EDF have stated that demand in London is growing and they and the National Grid are therefore performing significant upgrades.

One of the biggest is upgrading a feeder from Brimsdown to London from 275KV up to 400KV.
Plans are underway to replace the high voltage cables that run along canal towpaths in central London with new ones of greater capacity.
More locally, a lot of local 11KV distribution cables in central London are being replaced with larger ones, or supplemented with additional circuits.

Additional electric railways such as crossrail, and upgrades to existing lines are also increasing demands not just for traction but also for lighting, lifts, escalators, cooling and the inevitable "retail opportunities" in the stations.
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adam2
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PostPosted: Mon Sep 26, 2016 9:58 am    Post subject: Reply with quote

clv101 wrote:
Yea, thanks for this Adam2, I wasn't aware of this detail... Load group F?
!


There are a small number of large consumers of electricity that have a DEDICATED HIGH VOLTAGE GRID CONNECTION and that are considered to be of great importance.
These customers are exempt from rota power cuts.
There are two lists
The "V" list, V=vital, and
The "F" list, F=food storage or processing facilities.

Hence no load group F, lest it be confused with the F list.

The "F list" is only for large facilities that are considered to be of national importance. There is no exemption for local food shops, wholesalers, bakeries and the like.

The "V list" is for other VITAL consumers, including electric railways, defence establishments, SOME major airports, and the electrical industry itself, and natural gas pumping stations.
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PostPosted: Mon Sep 26, 2016 12:34 pm    Post subject: Reply with quote

I suspect that if rota cuts become common the government will find most consumers consider the electricity to run their fridge,TV and computer is a VITAL National interest and elections will turn on how they solve the problem or not.
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adam2
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PostPosted: Mon Sep 26, 2016 5:20 pm    Post subject: Reply with quote

The position at present, (about 17-00) is interesting WRT the future.

Total indicated load=37GW
Coal =4.3GW
Nuclear =8GW
CCGT =19.3GW
Wind =1.1GW
Pumped+hydro =1GW
Interconnectors =1GW
Biomass =1.5GW

On a cold winter evening a peak of 57GW is just about possible, and over 52GW virtually certain.
So for the winter peak we need another 20GW to meet an exceptional but just about possible demand, and we definatly need at least 15GW more than is being generated tonight.

Is another 15GW available ?
Wind might be a lot more, but only the presently available 1.1GW can be counted on
Nuclear is doing unusually well tonight and might well be 1GW LESS than at present.
Another 1GW should be available from pumped +hydro.
Interconnectors cant be relied on for much more than the 1GW being imported at present, so no help there.
About another 4GW of coal capacity should be available.

That still leaves 11GW more to find for a normal winter evening peak, or another 16GW for an exceptional but just about possible peak.
We hopefully have about 1GW available from emergency diesel and OCGT plant.
That leaves at 10GW more to be found from our primary source of electricity, CCGT.
Do we have another 10GW of CCGT capacity ? or about 30GW in total, a substantial increase on last winters contribution from CCGT which was IIRC about 24GW.
And that is only for a rather optimistic peak load of about 52GW, it could well be several GW more.
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Potemkin Villager



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PostPosted: Mon Sep 26, 2016 7:17 pm    Post subject: Reply with quote

Since the load growth is mainly in the sunny south east and London does it it not make sense, reduce transmission losses etc, to build new capacity as locally as possible to demand?

May I propose, as a step towards keeping the lights on, that the new proposed Franco-Chinese project be trlocated to the London Borough of Westminster as a vote of confidence by HMG both in the concept and technology. Even greater utility could be obtained by incorporating a CHP district heating scheme to provide the Palace of Westminster, all adjacent government buildings and Buck House with low carbon heat. Wink
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adam2
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PostPosted: Mon Oct 10, 2016 9:03 pm    Post subject: Reply with quote

Tonight's figures for generation look interesting WRT the coming winter.

Wind, nuclear, coal fired electricity, and hydro/pumped storage production are all within the expected range, 1.4, 7.3, 5.2, and 2.5 respectively.

Indicated demand is about 38.

CCGT is over 22.

On a cold winter evening, indicated demand is likely to reach about 53, or about 15 more than tonight.

Diesel and OCGT could probably contribute 1, and coal about another 4, so that leaves another 10 needed, presumably from CCGT.
Do we have another 10 of CCGT ? for a total of 32 ? not so far as I am aware.
However TPTB seem very relaxed and at least fairly confident that all will be well.

BTW, the French interconnector is broken again, so that has lost 1.5, but it might be still/again broken in the winter peak.

All figures are in GW.
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