Eighth power systems computation conference (PSCC)

Helsinki, 19th-24th August 1984

This conference is held somewhere in Europe every threeyears, and, since 1963, it has gained in popularity, numbersattending and proliferation of papers. With 1253 pages ofProceedings, the 1984 Conference passed previous recordsand seemed to have come up to the expectations of most ofthe 260 participants. As usual, many old friends from allover the world gathered for the technical sessions, andmany of the papers presented appeared to be old friendstoo! Not unnaturally, many papers summarised the devel-opment and research of familiar projects over the past 3years, so that the amount of new material was a small frac-tion of the whole.

Each day began with a state-of-the-art lecture, in whichdevelopments in a particular area were highlighted andpossible future scenarios were outlined. To set the ballrolling, Prof. M.A. Laughton, the Chairman of theOrganising Committee, in the opening session expressedsurprise that there were very few papers using the latestdevelopments in information technology, such as expertand knowledge-based systems, and he pointed out thedangers of power engineering becoming a twilight industryunless modern methods of computing, communication andcontrol theory were applied. Bright young students wouldnot be attracted to the industry unless these methodsfigured prominently in the many problems still to besolved and the applications needed in the power-systemarea. Research resources were now being provided all overthe world for work on these topics and power engineersshould not let them pass by.

Other state-of-the-art lectures covered power-systemcontrol by Prof. Sekine from Japan, network switching forsecurity by Hans Glavitsch (ETH, Zurich), distributedcomputing for dependable systems by Dr. T. Dillon(Monash, Australia) and modern automatic generationcontrol by Jacques Carpentier (EDF). In all these talks, thespeakers emphasised the need for understanding the tech-niques required to apply the theory and computation forthe reliable and economic operation of the system. Robust-ness and applicability were keynote words, althoughJacques Carpentier preferred the quaint term 'rustic', toavoid the kind of robustness implied in modern controltheorems.

Planning

Of the 30 papers under this heading, which, of course,includes generation, networks and reliability, one by Satohand Serizawa (Japan) was noteworthy in putting forwardideas for planning generation under uncertainty, usingfuzzy linear programming techniques. In view of Prof.Laughton's strictures earlier in the Conference, it is to behoped that more researchers will develop these methods,perhaps using expert systems, in future conferences. Otheruseful papers dealt with optimisation methods for gener-ation from CHP, storage, as well as alternative energysources. On the network side, the optimal location ofshunt compensation was an active topic, but we werewarned that this could be a large problem if the decisionvariables are numerous. Sensitivity techniques for networkexpansion were expounded, as were the varied andgrowing volume of data and methods for reliabilityanalysis, especially those which can apply a measure oflikelihood selection to possible contingencies.

Machine and system analysis

Several competing principles were apparent in papers inthis area. Those authors primarily interested in networkbehaviour tended to represent machines by unduly simpli-fied models, whereas those whose major concern was themachine behaviour employed high-order representation,giving rise to system models with 'stiff differential equa-tions, in which both large and small time constantsrequired careful and long calculation. Several mathemati-cal system dynamic models were described, but it was notclear whether the need for efficient large-time-step calcu-lation under transient swing conditions had been recon-ciled with the need for precision in determining out-of-stepoperation with the rest of the system and subsequentbehaviour. Prof. Fouad (USA) showed how direct methodsof assessing transient stability by energy functions couldnow be used in place of step-by-step solutions, and sug-gested that the utilities should now apply these methodsonline to assess stability margins. The problem remains,however, of including stability in the security assessmentfunction and of providing a cost to it in relation to otheraspects of economic system operation. Another approachby Mr. Dineley (UK), using catastrophe theory, had inter-esting possibilities in showing the nearness of system insta-bility to the operator.

Dynamics and control

Several papers dealt with control methods and dynamicsof systems. Honderd (Netherlands) advanced the use ofaccelerating power (mechanical-input/electrical-output) asa feedback signal to improve voltage control and Maun(Belgium) described a controller to decouple power andvoltage to produce a more straightforward design. Paperson multivariable optimal output control indicated, yetagain, the possibilities of improved control at the expenseof some complexity. Regulators based on ad hoc principles,such as power-system stabilisers or discontinuous control-lers, will only match the performance of a multivariablefeedback system if all possible disturbances are taken intoaccount. A single generator is very rarely in the single-machine/infinite-busbar situation and interarea oscil-lations, in which any one machine will be participating,requires much more consideration; a theme reinforced byDr. T. Dillon in summing up the Conference on the lastday. In designing controllers, the engineer must accountfor possible network and generator changes and these canrarely be forseen. Thus, an adaptive controller is requiredwhich can take into account system changes either auto-matically or by later design, as suggested in several papers.However, highly complicated and expensive controllerscan only be justified if they show substantial advantagesover traditional methods. Such advantages are nowlooking more likely with the development of area controlregimes, using online facilities to combat interarea effectsemploying digital schemes in a hierarchical mode. A majordrawback, at present, is the inability to model satisfactorilythe behaviour of loads under both voltage and frequencyvariations against time. A number of papers looked at thisproblem, but online identification of load characteristics isstill in its infancy. Encouraging progress on power-plantidentification was reported by Prof. Hogg (Belfast), and theextension of these and other methods to load dynamics isawaited with interest.

1EE PROCEEDINGS, Vol. 131, Pt. C, No. 7, NOVEMBER 1984 363

Simulators, processing and protection

A full session on simulators for operator training and con-troller development, from Japan, UK, USSR and Finland,underlined the growing importance of this topic for thesuccessful control of the power system. Parallel processing,too, had a full session, in which problems of decouplingcomputations to speed up their processing were aired. Indigital protection, the improvement in speed and reliabilityof microprocessors has instigated research into travelling-wave methods of fault detection. Methods which enablefaults on lines and cables to be identified within 5-10 ms oftheir occurrence were discussed. Under these circum-stances, the exact nature of the line representation wasquestioned as the impedance of a line to a travelling waveshould take into account its higher frequency response,rather than just the fundamental steady-state parameters.Methods involving the use of the 'telegraph' equations forline representation are looked for in the future.

Summing up the Conference

One of the useful and quite popular innovative features ofthe PSCC this year was the poster sessions, held in twoafternoons, when papers presented at the 22 working sess-ions were available with their authors for further individ-ual discussions. Not only could abstruse points be clarifiedbut also the authors could be 'got at' privately, if theirtheory was thought to be incorrect or they had not

appeared to have considered other research in their field. Itis encouraging to realise that other researchers face thesame difficulties as oneself and that some problemsencountered in the past are now perfectly solvable. Never-theless, all power-system researchers should continue topursue their own, often esoteric, ideas, but not to forget theoriginal aims of their research and to remember that allpractical systems must have realistic constraints. There islittle to recommend a study with totally unrealistic par-ameters or limits. Practising engineers, whether in a utility,industry or consultancy, should for their part be preparedto try the new methods and to grapple with the novel prin-ciples involved because the benefits are often worthwhile.Only by being venturesome can progress be made. In thenext few years fast computing and communications withdevelopments in expert systems have the potential totransform power systems into reliable, cheap and efficientprocesses for energy transfer, from which we can allbenefit. PSCC is an opportunity for new possibilities to beexplored between researchers and users. Who knows, in 3years time, it is possible that emphasis will have changedfrom deterministic planning, operation and control tofinancial modelling, stochastic planning and variablepricing of electrical energy. Then the single paper on spotpricing by Prof. Schweppe (USA) in this conference will nolonger be on its own.

B.J. CORYD.C. MACDONALD

3495C

364 IEE PROCEEDINGS, Vol. 131, Pt. C, No. 7, NOVEMBER 1984