IEE North Eastern Centre:Chairman's Address

Electricity supply-the changing phasesW.K. Harrison. J.P., B.Sc.

Indexing terms: Power transmission and distribution

The forecasting problem

For most of its first 100 years the ESI experienced a long-term average growth rate in the demand for electricity of7% a year: equivalent to doubling the business every 10years. With that rate of growth, forecasting has alwaysbeen an important exercise, first, because, in each decade,the ESI required more of the nation's total capital invest-ment. Secondly, because of the long lead time betweenordering and commissioning new plant, forecasting accu-racy had a direct effect on operational and commericalefficiency.

The forecaster's problem lies in anticipating the demandwhich will arise from the individual decisions of millions ofcustomers for up to 8 years ahead: customers who havenot even thought about the equipment they will be usingby then, and who will be able to acquire that equipmentover very short time scales. Although the consistency ofthe growth pattern helped to ease the problem, there wasalways the feeling that growth could not continue forever.When would it end?

Not surpisingly, the growth rate held up well through-out the 1950s and 1960s, a period of postwar recovery, ofgeneral economic expansion and rising standards of living.Nevertheless, it is worth bearing in mind what was hap-pening to the fuel market as a whole during that period.Between 1950 and 1970, total energy consumption rose by50% from 240 MTCE (millions of tonnes of coalequivalent) to 360 MTCE, an increase of 120 MTCE whichequals the present output of the UK coal industry. Thatincrease arose firstly because imports of cheap oilincreased tenfold between 1950 and the 1970s from 19MTCE to 190 MTCE. Secondly, we began to importnatural gas in 1959 and by the mid 1960s cheap North Seagas became available.

Despite these severe competitive pressures, electricityheld its growth rate, which as late as 1973 was still wellover 7%. However, at that point, the basis of the energymarket changed dramatically when the price of oil quadru-pled and coal prices doubled.

Because electricity is made from coal and oil, its pricealso rose but by less than the other two fuels. The elec-tricity growth rate fell immediately and has not yet re-covered.

Consequently, the price and availability of other fuelsassumed a much greater significance than before, makingforward predictions very difficult in a changing market.These uncertainties focused attention on the need for anoverall energy strategy which continues to affect the wholeenergy scene and the market for electricity.

Abstract 2691C of address delivered at the University of Newcastle, 11th October1982

Mr. Harrison is District Commercial Manager of the North Eastern ElectricityBoard, Carliol House, Newcastle upon Tyne, England

The energy strategy

The first attempts at an energy strategy, prompted by therealisation that energy resources were limited, were basedon continuing expansion both in the economy and in thedemand for energy. This led to first predictions that, as oiland natural gas resources diminished, the energy gapwould be filled by electricity supplying 60% of all energy,mainly from nuclear plants: 105 GW by the year 2000,365 GW by 2025.

This view was tempered by the Flowers Report in 1976which advaocated a more varied energy mix, of which elec-tricity would have a 20% share. The Flowers strategy wasbased on:

(a) a greater use of our abundant coal resources(b) substantial use of synthetic natural gas (SNG)(c) development of renewable resources, and CHP and

in particular a much lower nuclear component: 25 GW by2000 and 80 GW by 2025.

The energy mix

It is interesting to see whether those 1976 assumptionsabout future energy trends have been realised.

It was predicted that the 1973 price rises would reduceenergy consumption immediately by 20%, and even as theprice effect wore off the reduction would still be over 10%after 10 years. The following figures show that annualreductions from 1973 were much less than expected — wedid not become a nation of conservationists:

1974-5%

1975 1976- 8 % - 6 %

1977-4%

1978- 3 %

1979+ 1%

1980 1981-7% -10%

By 1979, after only 6 years, the 1973 figure was exceededand the fall in 1980 and 1981 was probably due to oil andcoal price rises in 1979 and 1980.

The following figures point to reasons for deviationfrom the predictions and show how different marketsectors behaved over the 7 years:

IndustryTransportDomesticOther

Total

1963%41182912

Mt116518235

284

1973%4320.52412.5

Mt149718343

346

1981%33252913

Mt105799241

3T7

DifferenceMt- 4 4+8+9- 2

%- 3 0+ 11+ 11

- 5

The following points can be drawn from these figures:(i) Substantial savings in fuel consumption were made

by industry in this period during the first part of whichlabour rates rose faster than inflation, so reducing profits.Therefore, as cost savings including fuel cost savingsbecome more important, it is likely that much of the 30%

IEE PROCEEDINGS, Vol. 130, Pt. C, No. 5, SEPTEMBER 1983 269

cutback by industry was due to energy conservationschemes.

(ii) The 16% rise in the transport sector indicatesloyalty to the car whatever the price of fuel.

(iii) In the 'other' sector, savings made by,conservationschemes have been offset by increases in the retail, leisureand entertainment market.

(iv) The domestic sector increase shows the effect ofnatural gas sales on the energy mix. Natural gas was theone fuel not affected by the 1974 price increases. Theresulting price imbalance attracted business to gas and, inparticular, increased consumption in the domestic sector.Those trends are borne out by the figures of final use of thedifferent fuels over the same period shown in Table 1.

If so, SNG could take a bigger share of future coal output,leaving less coal capacity for electricity generation.

It is important to remember that, in 1950, oil imports of20 MTCE were only 8% of the total energy needs, and by1974 had increased to 200 MTCE or 50% of the total. Theuse of North Sea oil has reduced oil imports to the 1950level, but as home produced oil supplies begin to diminishwe will have to find alternative energy sources to avoid areturn to high oil imports. This would put pressure onindigenous coal supplies for electricity generation or by thedirect conversion of coal to hydrocarbon products.

Even if UK fuel usage remains unchanged, there will bean energy shortage as North Sea gas and oil tail off. Boththe Flowers Report and the coal industry's own plans are

Table 1 : Energy consumption by final(Heat supplied basis—millions of therms)

Solid fuelGasElectricityOil

1973

1280011000

750029600

1974

1170012100

730027000

1975

1010012700

730025700

users

1976

990013800

740026200

1977

9700145007500

26700

1978

9000154007700

27100

1979

9500168008000

27400

1980

730016800

770024800

1981

7400169007500

23100

The changes in percent terms during the period were:

Solid fuel sales fellOil sales fell byElectricity salesGas sales increased

by

by

42%22%no change54%

in volume terms

The changes in market share in that period were:

Solid fuelGasElectricityOil

197322%18%12%48%

198113%3 1 %14%42%

We see the decline of coal, the stability of electricity andthe growth of gas. The surprising feature is the retentionby oil of its market share, mainly due to increased con-sumption by road transport.

The way in which the fuel market has reacted since1974 indicates that more than simple market forces are atwork. Otherwise, one would have expected gas, the cheap-est fuel, to have taken a larger slice of the market and oil,which is the dearest fuel, to have lost much more ground.Naturally, price has been a strong influence, but the avail-ability of particular fuels has also been an importantfactor.

For example, low price of gas initially produced astrong swing to that fuel, which the gas industry counteredby restricting the volume it would supply to industry. Thismove to reserve gas for the premium markets, predomi-nantly domestic, was in turn countered by accelerated risesin domestic gas prices, which made fuel prices more com-parable. These manipulations of the market had a notice-able effect in containing the demand for gas. Even coal,which has lost ground because of price, is finding impor-tant sectors of industry returning to coal firing becausethat fuel is readily available. In the same way, the abun-dant supplies of petrol and diesel, coupled with strongloyalty to road transport, have nullified the high price ofoil.

These distortions will have important consequences forthe long-term energy scene: first, the market share held bygas could continue to grow despite price manipulation andthat loyalty may continue even when natural gas runs out.

37%35%23%5%

= 117= 111

7316

= 317

MTCEMTCEMTCEMTCEMTCE

based on achieving a production level of 200 MTCE bythe end of this century, but it looks increasingly doubtfulwhether that target will be attained. It is doubtful, there-fore, whether coal can be produced in the quantitiesrequired or at acceptable prices.

These factors make forecasting future energy demandsvery difficult and emphasise the need to consider thenuclear options.

The nuclear options

The total UK primary fuel consumption of 317 MTCE issplit up as follows:

coal suppliesoil suppliesgas suppliesnuclear and hydro supplytotal

Oil and gas, between them, account for two-thirds of thetotal or nearly 200 MTCE. If we can maintain fuel con-sumption at present levels indefinitely, then, as oil and gassupplies diminish, we will have a 200 MTCE energy gap tofill. That gap can be reduced by the following:

(a) Increased coal output could bring it down to 120MTCE but the timescale is problematical.

(b) Determined energy conservation could contributeabout 30 MTCE.

(c) Development of CHP might contribute about 20MTCE.

(d) Renewable sources of energy will play a relativelysmall part, depending on the timescale.

This would leave a 70 MTCE energy gap to fill, and,although the magnitude and timing of the various factorsin the energy equation can and will vary, it seems inescap-able that a substantial nuclear plant programme will beneeded to close the energy gap.

We have to face up to this issue objectively and ration-ally, but the use of nuclear power on an increasing scale aspart of our energy strategy does not lend itself to easyanalysis. There seem to be three reasons for this: First, thestrongly held, well-informed views of the pronuclear and

270 IEE PROCEEDINGS, Vol. 130, Pt. C, No. 5, SEPTEMBER 1983

antinuclear lobbies tend to exaggerate arguments for oragainst. Secondly, there are genuine differences of viewbetween engineers and scientists concerned with the manu-facture and development of nuclear plant about the choicetechnology for the future. The third point arises from thesheer scale of the resources which have to be committed

over a long timescale.There is no doubt that these factors will ensure that the

nuclear issue, with all its complexities and the importantbearing it will have on the future energy pattern, will bewith the electricity supply industry for the whole of theforeseeable future.

Abstracts of papers published in other Parts of the IEE Proceedings

The following papers of interest to readers of IEE Proceedings Part C, Generation, Transmission & Distribution haveappeared in other Parts of the IEE Proceedings:

Long-term management of energyPROF. M.W. THRING

IEE Proc. A, 1983, 130, (5), pp. 281-287

It is the author's view that, on a long term basis, a stableworld free from major war is only possible if the developedcountries reduce their energy consumption to about thepresent world average per-capita figure, i.e. about 2 tons ofcoal equivalent per capita per annum (2 TCE/c.a), and helpthe underdeveloped countries to achieve self sufficiency inenergy and food at a comparable level. Both from thispoint of view and because of the cost of energy to theconsumer in the rich countries, the author believes that theonly feasible long-term policy for a developed countrysuch as Britain is as follows: (i) There should be invest-ment in energy conservation by investing capital and byother methods (such as the elimination of built-inobsolescence) as if fossil fuels cost several times as much asthey do. (ii) Electricity is too precious a fuel to waste onthe low-grade purposes of space and water heating, and sowe should not build any new power stations but convertold ones in cities to coal firing with pass-out heat systemsfor houses and industry. This would give fruitful employ-ment to the construction and heavy-engineering industriesfor many years, (iii) Solid fuels (preferably smokeless)should be available for all space and water heating when-ever pass-out heat from power stations cannot be madeavailable. Research on manless coal mining should becarried out very actively, (iv) A substantial amount of Gov-ernment money (e.g. 20% of that spent on defence) shouldbe devoted to 'intermediate' or 'alternative' technology,especially on the provision of village renewable energysystems.

General theory of fast-fronted interturn voltage distributionin electrical machine windingsM.T. WRIGHT, S.J. YANG and K. MCLEAY

IEE Proc. B, Electr. Power Appi, 1983, 130, (4), pp.245-256

Motor-coil failure caused by high interturn stressing canoccur because of the application of fast-fronted switchingsurges to the stator winding. It is shown that a newmethod of analysis of surge propagation in coils is necess-ary. A generalised method of analysis, which is capable ofpredicting voltage distribution in coils due to fast-frontedsurges, is developed. The analysis, omitting losses, givesresults which are significantly more accurate than thosepreviously published. Further development of the analysisto include losses is also given. A comparison of measuredresults and results predicted by the lossy model shows themodel to be extremely accurate. It is demonstrated thatsurges propagate through coils in both a series and aparallel manner and that each mode of propagation

cannot be treated separately. (See also WRIGHT, M.T.,YANG, S.J., and MCLEAY, K.: The influence of coil andsurge parameters on transient interturn voltage distribu-tion in stator windings', IEE Proc. B, Electr. Power AppL,1983,130, (4), pp. 257-264.)

The influence of coil and surge parameters on transientinterturn voltage distribution in stator windingsM.T. WRIGHT, S.J. YANG and K. MCLEAY

IEE Proc. B, Electr. Power AppL, 1983, 130, (4), pp.257-264

Steep-fronted switching surges can cause undesirable tran-sient voltage distributions in stator windings, resulting inseverely stressed interturn insulation. The effects of coiland surge parameters on transient voltage distribution arenot well understood. The paper reports the results of aninvestigation into the effects of these parameters. Theinvestigation was carried out using a new coil model whichhas been shown to have good accuracy. The voltage dis-tributions on coils of various shapes, for a range of surgerisetimes, were found. In addition, the variation of voltagedistribution with the dimensions of the coil insulation werecomputed for the range of surges. The variation betweenthe proportion of the surge which appears between turnsand the surge risetime is given. It is demonstrated that anincrease in p.u. interturn voltage is the result of an increasein interturn insulation thickness. The shape and size of thecoil are shown to have a decreasing effect on the magni-tude of the interturn stresses as the surge risetime isreduced. The effects of the parameters on winding surgeimpedance are illustrated and discussed, although it isshown that the concept of a machine surge impedance is oflimited value. (See also WRIGHT, M.T., YANG, S.J., andMCLEAY, K.: 'General theory of fast-fronted interturnvoltage distribution in electrical machine windings', IEEProc. B, Electr. Power AppL 1983,130, (4), pp. 245-256.)

Testing of solid-core insulators for use on BR 25 kV electri-ficationJ.C.G. WHEELER

IEE Proc. B, Electr. Power AppL, 1983, 130, (4), pp.278-283

A salt-fog test for porcelain insulators is described and theresults are presented which compare it with the wet test inBS137 as a means of determining the suitability of an insu-lator for use on BR. It is maintained that the salt-fog test isa superior technique and, furthermore, can be used as aresearch tool for optimising shed design. A relationship isderived which equates natural pollution levels in servicewith the salt-fog withstand levels applied in the laboratory,and values of salinity are quoted which porcelains mustwithstand before being accepted for use on BR.

IEE PROCEEDINGS, Vol. 130, Pi. C, No. 5, SEPTEMBER 1983 271