Talk:National Grid (Great Britain)

Cost per kWh of Transmission

User:Engineman - Can't you find some published material on the transmission costs for wind power? I appreciate this is an important subject, but the current claim seems to be based only on your own research. The policy against original research does not only apply to factual information, but also to "arguments, ideas, data, or theories." Thanks, Crosbiesmith 20:12, 15 November 2006 (UTC)

Crosbiesmith - Sorry I do not understand your point above - I have referenced in the article the published rates for the cost of the transmission network from the National Grid themselves, so that is surely a solid reference and not research.

http://www.nationalgrid.com/uk/Electricity/Charges/usefulinfo/

http://www.nationalgrid.com/NR/rdonlyres/E5B27828-6705-4F21-9B4B-0A998D7AFA5C/5849/FinalTariffs2006_2007.xls

I have then performed an obvious calculation and divided the total receipts based on that charging rate and divided it by the published total of kW hours sold, to give the average unit rate of the cost of the transmission network.

So I have taken published reference source material and shown that at the present, the entire cost of the UK national Grid transmission network is the surprisinly low cost of 0.2 p/kWh.

I do not see how that is original research, or how it needs any further reference, but correct me if I am wrong.

I have then, purely by way of example, said, that by inference, if the size of the transmission doubled,trebled or quadrupled (none of which I am saying will happen) then this would presumably , double, treble or quadruple the cost of transmission.

The original calculation was in a paper read at a conference at the Open University so surely that counts as a reference in its own right.Engineman 14:37, 16 November 2006 (UTC)

http://www.ukerc.ac.uk/content/view/258/852

It was only the last paragraph, the example concerning wind power, that I was questioning. I didn't check the first part. Was the paper read the 'UKERC Intermittency Report'? Or was it some other paper? - Crosbiesmith 19:47, 16 November 2006 (UTC)

Apologies Crosbiesmith - I gave wrong reference - should have been this:

http://eeru.open.ac.uk/conferences.htm#jan06

crosbie smith - ok I see your point now....and have reworded .....hope that suffices.... engineman...

OK, just done a massive rewite of this section. Hopefully the explanation is somewhat clearer. RDevz 18:41, 26 March 2007 (UTC)

Losses

In the losses section:

Fixed losses: 266 MW (consists of corona and iron losses; can be 100 MW higher in adverse weather)

Is iron a typo? The wikilink to iron doesn't make it any clearer. JimChampion 86.144.73.92 20:10, 5 December 2006 (UTC)

Link Nr. 6 does not work !! —Preceding unsigned comment added by 129.27.129.17 (talk) 13:52, 19 June 2008 (UTC)

---

The "iron loss" is not a misprint, although it is loose terminology that I personally do not like. "Iron loss" originally referred to the loss of a small percentage of the power within the magnetic steel of a transformer. In transformers, this type of loss is determined entirely by the voltage of operation of the transformer, and is completely independent of the current (or MVA) of the transformer load. In cables and overhead lines, there is also a small loss of power in the dielectric, caused (as in the transformer) entirely by the voltage, and not at all by the current carried by the cable/overhead line. This type of loss is caused by imperfections of the dielectric insulator in cables, and by the energy lost by HV corona activity on overhead lines. Because the loss is analytically similar to the "iron loss" of transforers, people started to call it the "iron loss" of the power cable or overhead line. Personally, I prefer to be more accurate, so I call it the "voltage-dependent loss". It can also be called the "fixed loss", because the voltage of a 400kV line on the Grid is either 400kV or zero, with only a +/-5% variation. DickChambers (talk) 23:52, 6 June 2014 (UTC)

Transmission costs

Ive put back the estimation of transmission costs as being 0.2 p/kWh since it was removed without any explanation, discussion or counter argument.Engineman 21:58, 3 April 2007 (UTC)

The reasons for my removal of it were twofold: Firstly, the section simply didn't flow properly. Secondly, you don't appear to have understood the underlying charging methodology. I'll refer you to the Statement of the Use of System Charging Methodology (found on http://www.nationalgrid.com/uk/Electricity/Charges/chargingstatementsapproval/ ), which explains how the charges are calculated. It simply isn't a case of Triad demands - they're only used in determining how HH metered sites are billed for TNUoS. NHH sites are billed based on their total consumption between 1600 and 1900 local time over the course of an entire year, and generators are billed based on the amount of TEC they have.

If you want to work out the cost of transmission, a much better way is to divide the total allowed revenue (see: Transmission Price Control section of Ofgem's website (www.ofgem.gov.uk)) of £653m in FY 2006/07 by the total demand of the GB transmission system, of around 360 TWh. This gives you an answer of 0.18p/MWh. Yes, this is similar to what you have already, but it's a sounder basis, as opposed to blindly asserting it. RDevz 23:37, 7 April 2007 (UTC)

RDevz - thanks for the correction - can't accept it was blind assertion I spelt out exactly my assumptions which were near enough. Could you, since you obviously know a lot more about it than me, correct the article on transmission costs then? I assume you mean 0.18p/kWh not 0.18 £/MWh. The point is the costs are very low compared to the energy and other costs - presently around 8 p/kWh by the time it gets to my house any way. Engineman 20:32, 24 April 2007 (UTC)

Um, yeah. £0.18/MWh is obscenely low. I think I meant £1.80/MWh. In my defence, it was late at night. I'll make the necessary adjustments when I'm more awake. RDevz 02:28, 25 April 2007 (UTC)

Update from an expert, Bernard Quigg, CEng. etc writes"

Dave, Yes and no. So long as you don't actually use the transmission system to move power any distance it is cheap. Otherwise it is not. Thus we pay triad charges of 2200 pence per annum for a kW of capacity and the system load factor is about 0.6. Triad charges alone are circa 2200/8760 with the answer divided by 0.6. Thus for us, triad charges are 0.42p/kWH. If we add the exit charges hidden in distribution charges and charges for the generators to put power into the network then we will not be far off the 1p/kWH for say about 200kM of transmission. Do the transmission losses appear in the allowed revenue? If they are put into the trading mechanism they may be hidden as they are not then in the allowed revenue. Rgds Bernard Quigg"

I would only add that the charges Bernard is talking about are for the extreme South West where they are bound to be more expensive...but I suppose that is fair..Engineman 17:52, 25 April 2007 (UTC)

There is a typo, the section ends with "Other estimates give a much lower figure of 0.2p/kWh.[19]" but this is the same value given earlier so it is not "much lower".--85.205.122.153 (talk) 14:05, 7 March 2011 (UTC)

Further comments on Bernard Quigg's points

“How much does it cost to shift electricity within the UK at semi market related prices?”

Bernard,

I am sure your facts are correct, but I don’t think your answer to my question is right.

Any generator will have to pay the access charges be they a new nuke or a wind farm and they will appear in the respective business case so don’t count.

All electricity that comes from a GSP no matter what its origin or distance has to pay the exit charges so don’t count either.

So the cost of getting it say 200 km (surely 400 km) from a point in the HV near the large coal stations to the Wessex Area GSPs will be only the Triad charges, and as you say these are about 0.42 p/kWh,.

My error had been in averaging the Triad charges for the whole country who pay much less because they are nearer to the coal field power stations than Wessex which is why I got 0.2p

So it seems to me that the answer to the question “ how much does it cost to shift electricity within the UK at semi market related prices over about 200 km (surely 400 km) is about 0.42 p/kWh.

Any advances anyone?

Engineman 20:10, 25 April 2007 (UTC)

Comments from GB

There is another factor to consider here. The total transmission cost is apportioned between generation and demand users on a 25/75 split (at least it used to be this). The total costs are based on the transmission system usage at the three peak periods (i.e. triads). Therefore if you are going to use triad payments as an approximate method to estimate the cost of transmission then you have to increase this by about 1.33 to account for the 25% contribution from generation that is hidden from your triad charges.

Just for reference, a new-build 275kV double circuit line will give a "firm" capacity of about 800MVA and a recent cost estimate is in the region of £1.2M/km installed. This equates to a capital cost of £1.5/kVA/km or £300/kVA for the 200km reference. This asset probably has a 40 year useful lifetime and so apply a reasonable discount rate to calculate the replacement cost of transmission. This will give an upper end cost estimate.

Regards,

G Engineman 17:35, 26 April 2007 (UTC)

Comments from a leading UK consultancy

Maurice

Firstly, Triad is locational and so you cannot extrapolate a southern triad into a national revenue.

Secondly, Triad is a return on the fixed costs of providing the wires and not a cross-subsidy.

Thirdly, BSUoS is a mix of mainly bought in transmission services (reserve, frequency response, reactive power etc). The exception is constraint costs, which may be considered a potential cross-subsidy for wires not-provided, except that wires not-provided, do not go into the asset base and earn a return anyway.

Finally, both BSUoS and Triad now cover for GB wires and services and not just NGET’s transmission system.

The final transmission price control Ofgem proposals for the 5-years starting in April 2007 give:

Total allowed revenue for TNUoS (NGET, SPT, SHETL): £1299m. This is 73% on supply and 27% on generation. This gives an average triad on peak day throughput of 60 GW (that was the peak for 2005/6) of £15.59/kW for demand. Generation TNUoS is based on TEC rather than peak day throughput but I am not sure they are interested in that. So approximating as £2.75/MWh

BSUoS incentive for 2007/8 is proposed at £440m (of which about £80m would be allowed for constraint costs). On a throughput of 344.8 TWh (2006/7 but I haven’t checked on allocation of losses in the BMRS figures for initial demand outturn on which I based this figure) then BSUoS is about £0.64/MWh on generation and on demand.

This gives £3.40/MWh on demand plus whatever comes through distribution on the T/D connection charge

I am also intrigued by their use of figures on diesel reliability. Outside demand control it is 85% but in demand control (presumably offered into standing reserve?) it is 50% due to load management in storms.

By the way, what is the concern about NGET revenues given that we have Ofgem attempting to keep them under control they will not be significantly different from what competition could deliver – i.e. that is what it costs to run the system and only limited fat can be carved out.

Rob

Engineman 17:38, 26 April 2007 (UTC)

Major incidents

I've added a bit on the 28 May 2008 DCI but I'm know little about the technicalities and details appear to be scarce because they "want to maintain confidence in the network" as someone said on Radio 4 !? I presume that a DCI is a sensible criteria for inclusion although the last one occurred 4 years ago which seem rather too frequent ? The big one would presumably be the 1987 storm damage. Is it correct that too low a voltage is as damaging as too high a voltage ? What are the agreed bands ? They talk about frequency but do they mean voltage ? It would be nice to have a section on the emergency procedure, here's the link [1]. Thanks -- John (Daytona2 · Talk · Contribs) 13:10, 31 May 2008 (UTC)

The comments regarding ROCOF are slightly wrong. This relay is used to detect a 'loss of mains'. this is when the generator has become disconnected from the grid.Kletops (talk) 19:44, 31 October 2012 (UTC)

emergency procedures for loss of generationg capacity

These links are from the excellent

http://energydiscussiongroup.wikispaces.com/

Engineman (talk) 14:12, 19 June 2008 (UTC)

http://energydiscussiongroup.wikispaces.com/space/showimage/JET+DINORWIG+CEGB.pdf

Extract from CEGB manual showing how National Grid deals with a large demand surge form JET

http://energydiscussiongroup.wikispaces.com/space/showimage/Page138.pdf

Extract from CEGB manual showing how National Grid copes with loss of power

Transmission costs again

The reference given for the section on transmission costs gives this document as a reference: http://www.claverton-energy.com/download/147/

• Referring to page 9, the total transmission power is calculated at 2.7p/kwh.
• The NGC portion of the figure is .71p /kwh.

These figures are quite distant the .2p/kwh figure given in the article, so perhaps the passages needs updating to this 2008 document, or a source that supports the .2p figure should be found. -J JMesserly (talk) 23:02, 24 December 2008 (UTC)

The .2p number seems ridiculous and a very minority opinion. I've removed the section entirely. TastyCakes (talk) 15:42, 8 April 2009 (UTC)

Engineman has replaced the disputed section. As no source has been given since it was requested last August, how are we to take this section as anything but original research? If no one (ie Engineman) can provide a solid citation, I think the whole bit on "triads" should be removed. TastyCakes (talk) 14:20, 9 April 2009 (UTC)

Hang on a minute - Triad charges are well understood by people in the industry and are dealt with every day by people who deal with power bills - the charges are on every Half Hour electricity bill, and are available on the National Grid and Elexon websites.......from these charges which are not in dispute, surely it is reasonable to indicate the likely range of kWh charges?

Can anyone advance any contrary evidence, that transmission charges are in fact higher? If so what sources?

The reason the UK national grid was built in the first place was because it was realised in 1925, Lord Wier, that there were huge advantages in having less, more efficient stations and transmitting the stuff over long distances - that is why electricity costs came down after the UK and all other national grids were built.Engineman (talk) 12:35, 10 April 2009 (UTC)

Transmission losses

I have one comment, and one question, both relating to the section on power losses on the transmission system. 1. The power losses in generator transformers are the responsibility of the power stations, not of the National Grid. Some power stations meter the power on the 275/400kV side of the generator transformer, so that the cost of any losses in the transformer is borne entirely by the power station, not the National Grid. Other power stations (mostly the ex-CEGB stations) have received a dispensation allowing them to meter the power at the generator side of the transformer. Where this is allowed, the power station is required to compensate the meters to account for the losses in the transformer. Whichever method of metering is used, the National Grid receives the power/energy that the metering has recorded. For this reason, the losses in the generator transformers cannot be considered a loss from the Grid. 2. On the subject of transmission losses, I wanted to follow up the references that the article provided. The "2005 Seven Year Statement", or "2005 SYS", is now unavailable on the internet. The 2011 SYS does not contain a section on the losses. Do you have any suggestions for how I should get hold of a copy of 2005 SYS? Are there any other references? I am particularly interested in the relative magniudes of the I-squared-R losses and the fixed losses of the Grid. DickChambers (talk) 00:22, 4 June 2014 (UTC)

For links?

The "interconnects" sections states: "including for links to northern France". I am guessing that this means FOUR links, however without any reference I am loathe to make the edit. --Davidcx (talk) 23:31, 3 July 2014 (UTC)

Error in History?

The History section includes "The growth by then in the number of electricity users was the fastest in the world, rising from three quarters of a million in 1920 to nine million in 1938.". That seems unlikely - I think that almost all properties (especially businesses) in urban areas, and many in rural areas, would have been connected by then. Maybe the original author should have written "customers" rather than "users". 94.30.84.71 (talk) 08:54, 1 August 2020 (UTC)

History Section - pylon design

At the end of the history section it mentions that the T-pylons at Huntspill are the first non-lattice pylons. There are tower pylons located on Cambridge Science Park (https://commons.wikimedia.org/wiki/File:Pylon,_Cambridge_Science_Park_-_geograph.org.uk_-_774903.jpg) which have been in-place since, I think, the 1980's. They operate at 132kV but I don't know enough about the topic to know if they are part of the National Grid or not... Acey (talk) 10:51, 9 May 2022 (UTC)

Thanks for pointing this out. I've changed the wording slightly. Regards Hallucegenia (talk) 12:41, 9 May 2022 (UTC)

per MW per hour

Ok I give up, why do we say "per MW per hour" and not "per MWh"? I know that's what the source says, but it's a really odd way of expressing MWh and I think we should use the standard terminology. GA-RT-22 (talk) 04:14, 10 October 2022 (UTC)

MWh is the measure of power delivered but this type of "reserve" purchase is a commitment to put plant on standby for X hours, ready to provide Y megawatts. The outcome is usually less than X times Y, and may even be zero MWh if the reserve is not called upon. Wire723 (talk) 14:47, 10 October 2022 (UTC)

If that's for a reservation I guess it makes sense, but that's not clear from the text. GA-RT-22 (talk) 15:45, 10 October 2022 (UTC)