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Case studies in mathematical modelling
Book Reviews Proceedings of the Seventh Power Systems Computation Conference
Lausanne, 12-17 July 1981, IPC Science and Technology Press,
Guildford, England, 1981, 1225 pp., £53 This rather massive volume is the product of the Seventh Power Systems Computation Conference. The organizing committee has endeavoured to present a comprehensive, if somewhat disjointed, discussion of issues critical to efficient operation, control and planning by utilities. One has to be impressed by the number of participants, the institutions they represent, and the participant's ability to communicate with one another. The organizing committee has done a valuable service by providing a forum for the exchange of ideas and information. The structure of the conference revolved around eight state-of-the-art topics and five major topic groups with a total of 14 subgroups. The stateof-the-art papers dealt with such issues as optimization methods in planning and operation of power systems, emergency control, dynamic control of large scale systems, microprocessors in electric power systems, parallel processing in power systems, on-line data bases, electrical power and energy systems, and controllable reactive compensation in real-time operation. Each of the authors of these papers is particularly knowledgeable about the topic and the substance of the papers convey useful information. Unfortunately there was an obvious page limitation that inhibited a complete exploration and evaluation of each of the issues. In the 'state-of-the-art' papers, this type of constraint should have been eliminated. There were five topic groups each with two or more subgroups. Issues of interest were planning (modelling and optimization in planning and probability methodology, reliability, operation, modelling and optimization in operations (two parts), control strategies for on-line system control, and uncertainty and forecasting), dynamics and control (similation and stability analysis, unit control, and medium and long-term dynamics), network analysis (network analysis, load flow, network analysis short circuits and transients), state estimation and parameter identification, and information processing (parallel processing and computer systems). The number of papers included in this proceedings volume are simply too numerous to comment adequately on each in a short review. Consequently, I will limit my observations to a few areas. Before doing this, however, I would like to make a general reflection on the papers. The conference partici-
pants (i.e., authors of the included papers) come from a fairly extensive cross section of countries. There is, however, a remarkable consistency in the approaches used in handling the problems of importance to a utility system whether it be a small, publicly owned electric utility in the United states or a state controlled and operated utility in France. The set of papers dealing with modelling and optimization in planning typically detail some type of linear programming formulation where the objective function is some type of cost relationship. Both short-term (hour-to-hour) and long term applications are discussed. A few of the papers dealt with new dimensions of this old problem. In particular, techniques for the inclusion of reliability constraints, mix constraints by fuel type, cash flow constraints, and atmospheric emissions are discussed in one or more of the papers. Moreover, considerations of the temporal trade-off in the addition to new capacity or retirement of existing capacity are explicitly included in one of the presentations. The papers in the sections on probabilistic modelling are especially good. Various techniques for computing loss of load probabilities are presented together with techniques for translating those probabilities into the determination of the maximum reserve of generating capacity, the precise identification of problem nodes - the grid system, and so forth. The section of the proceedings dealing with various forecasting aspects is somewhat disappointing. There are now accepted approaches to forecasting system requirements, be they short-term or longer term. The papers here are simply reporting on the utilization of these approaches without offering any extension of the techniques or any insights into their limitations or advantages. Thus, one finds moving average approaches, BoxJenkin's time series approaches, multiple regression approaches, etc., discussed together with concern over data and model inadequacies. The novice might find this of interest; the initiated, however, will learn nothing new. There is another fine collection of papers on simulation and stability analysis. Various simulation models are described which endeavour to investigate the effects of load representation on power system disturbance stability. Loads are for the most part in the papers simulated by static models with a range of voltage and frequency characteristics. Two types of marginally stable oscillation models are examined in the various expositions. One involves machine angles while the other focuses on excitation
140 'Appl. Math. Modelling, 1982, Vol. 6, April
system states. This should be sufficient to give the flavour of the papers included in this proceedings volume. For the most part, the papers are of value. (As in all such publications, there are a small, finite n u m b e r that would have best been omitted.) The volume should most properly be used as a reference. The papers, generally, contain concise summaries of the issue of interest but, more importantly, provide good references to other material in an area. Some papers in an effort to adhere strictly to the constraint on length are too brief to provide much information. A number of papers are written by individuals whlo do not communicate well in English (all of the papers are written in English or a variant thereof). As a result the contents are barely comprehensible. One particular oversight in the conference was the very slight attention paid to the impact that renewable energy sources (e.g., solar, biomass, photovoltaic) will have on power systems. The assessment of this is important for utilities, especially over the longer term. I would hope that future power system computation conferences would devote some time to this consideration.
Noel D. Uri
Case studies in mathematical modelling
(Ed. Bradley, R., Gibson, R. D. and Cross, M.) Pentech Press, London and Plymouth, 1981,167 pp., £14.00 The North East Polytechnics Mathematical Modelling and Computer Simulation Group held its inaugural conference, 'POLYMODEL 1', at Sunderland in May 1978. A second equally successful conference, POLYMODEL 2, was held at Teesside in May 1979. The proceedings of both conferences were published. This book is the outcome of POLYMODEL 3 held at Newcastle upon Tyne in May 1980. The editors have adopted a different format from that of the first two conference reports, and in this form the book should achieve a wider readership. Following an introduction which describes the modelling process with illustrations from blast-furnace performance analysis, the book presents six casestudies on such diverse topics as choosing a pick-up arm for a record player, deciding the correct diameter and spacing for rollers in a float-glass process, and determining the temperature distribution of meat during freezing or thawing.
Book Reviews
Each case-study presented includes a typical student-report, compiled by a team of modellers under workshop conditions, together with a critical assessment of the team's approach and a model solution prepared by the author. The book should appeal to any practitioner (including beginners) who wishes to gain further experience of modelling and to academics concerned with modelling-courses. The latter will not find in this a ready-made text-book but will find a generous stock of
material from which they can select cases to suit the needs of their students. The mathematical knowledge required is claimed to be no more than that of the average physical-science or engineering graduate and the actual level ranges from the elementary (the cosine rule and sine wave in the record-player problem) through the fairly familiar 9ordinary differential equations in the (ordinary differential equations in the float glass process problem) to the obscure (enthalpy and the Kirchhoff transform in the meat-freezing and
thawing problem). Barring a few minor syntax errors, the presentation is of a high standard, with clear diagrams and neatly laid out mathematical expressions. The consensus view at POLYMODEI. 1 was that it usually took three years to make a graduate mathematician into a modeller. This book should knock a week or two off that time!
22-23 April 1982
30 June-2 July 1982
25--27 August 1982
Thirteenth annual modeling and simulation conference
Computational methods and experimental measurements
Johannesburg, South Africa
R. Croasdale
CALENDAR Hydrotransport 8
Pittsburgh, USA
Washington DC, USA
W. G. Vogt, Modeling and simulation conference, 348 Benedum Engineering Hall, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA
Dr C. A. Brebbia, ISCME, 125 High Street, Southampton SOl 0AA, UK
12-14 July 1982 11-14 May 1982
6-9 September 1982
The mechanics of sediment transport
Istanbul, Turkey International conference on geothermal energy
Florence, Italy
Organizing Secretary, Hydrotransport 8, BHRA Fluid Engineering, Cranfield, Bedford MK43 0A J, UK
Prof. B. M. Sumer, Faculty of Civil Engineering, Istanbul Technical University, Istanbul, Turkey
Conference Organizer, Geothermal Energy, BHRA Fluid Engineering, Cranfield, Bedford MK43 0A J, UK
Period flow and wake phenomena
Berlin, Germany Prof. Dr.-Ing. E. Berger, HermannFtttinger-Institut fiir Thermo- und Fluiddynamik, Technische Universitgt Berlin, Strasse des 17 Juni 135, 1000 Berlin 12, Germany
9-13 August 1982 1-3 July 1982
1982 Annual transportation convention
Modelling and simulation
Pretoria, South Africa
Vallee de Chevreuse, France
The ATC Secretariat, c/o The National Institute for Transport and Road Research, PO Box 395, Pretoria 0001, Republic of South Africa
AMSE, 16 Avenue de Grange Blanche, 69160 Tassin la Demi Lune, France
12-15 September 1982
19-21 July 1982
1982 Design automation conference
Washington DC, USA Prof. K. M. Ragsdell, School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907, USA
19-21 August 1982 1982 Summer computer simulation conference
Denver, Colorado, USA Dr M. F. Anderson, Department of Electrical and Computer Engineering, University of Colorado, 1100 Fourteenth Street, Denver CO 80202, USA
Seventh symposium on operations research
13-17 September 1982
St Gall, Switzerland
International symposium on numerical methods in geomechanics
Prof. Dr H. Loeffel, Institut for Unternelunensforschung, Hochschule St Gallen, Bodanstrasse 6, CH-9000 St GaUen, Switzerland
Zurich, Switzerland Dr R. Dungar, c/o Motor-Columbus, Parkstrasse 27, Baden, Switzerland
Appl. Math. Modelling, 1982, Vol. 6, April
141
Lausanne, 12-17 July 1981, IPC Science and Technology Press,
Guildford, England, 1981, 1225 pp., £53 This rather massive volume is the product of the Seventh Power Systems Computation Conference. The organizing committee has endeavoured to present a comprehensive, if somewhat disjointed, discussion of issues critical to efficient operation, control and planning by utilities. One has to be impressed by the number of participants, the institutions they represent, and the participant's ability to communicate with one another. The organizing committee has done a valuable service by providing a forum for the exchange of ideas and information. The structure of the conference revolved around eight state-of-the-art topics and five major topic groups with a total of 14 subgroups. The stateof-the-art papers dealt with such issues as optimization methods in planning and operation of power systems, emergency control, dynamic control of large scale systems, microprocessors in electric power systems, parallel processing in power systems, on-line data bases, electrical power and energy systems, and controllable reactive compensation in real-time operation. Each of the authors of these papers is particularly knowledgeable about the topic and the substance of the papers convey useful information. Unfortunately there was an obvious page limitation that inhibited a complete exploration and evaluation of each of the issues. In the 'state-of-the-art' papers, this type of constraint should have been eliminated. There were five topic groups each with two or more subgroups. Issues of interest were planning (modelling and optimization in planning and probability methodology, reliability, operation, modelling and optimization in operations (two parts), control strategies for on-line system control, and uncertainty and forecasting), dynamics and control (similation and stability analysis, unit control, and medium and long-term dynamics), network analysis (network analysis, load flow, network analysis short circuits and transients), state estimation and parameter identification, and information processing (parallel processing and computer systems). The number of papers included in this proceedings volume are simply too numerous to comment adequately on each in a short review. Consequently, I will limit my observations to a few areas. Before doing this, however, I would like to make a general reflection on the papers. The conference partici-
pants (i.e., authors of the included papers) come from a fairly extensive cross section of countries. There is, however, a remarkable consistency in the approaches used in handling the problems of importance to a utility system whether it be a small, publicly owned electric utility in the United states or a state controlled and operated utility in France. The set of papers dealing with modelling and optimization in planning typically detail some type of linear programming formulation where the objective function is some type of cost relationship. Both short-term (hour-to-hour) and long term applications are discussed. A few of the papers dealt with new dimensions of this old problem. In particular, techniques for the inclusion of reliability constraints, mix constraints by fuel type, cash flow constraints, and atmospheric emissions are discussed in one or more of the papers. Moreover, considerations of the temporal trade-off in the addition to new capacity or retirement of existing capacity are explicitly included in one of the presentations. The papers in the sections on probabilistic modelling are especially good. Various techniques for computing loss of load probabilities are presented together with techniques for translating those probabilities into the determination of the maximum reserve of generating capacity, the precise identification of problem nodes - the grid system, and so forth. The section of the proceedings dealing with various forecasting aspects is somewhat disappointing. There are now accepted approaches to forecasting system requirements, be they short-term or longer term. The papers here are simply reporting on the utilization of these approaches without offering any extension of the techniques or any insights into their limitations or advantages. Thus, one finds moving average approaches, BoxJenkin's time series approaches, multiple regression approaches, etc., discussed together with concern over data and model inadequacies. The novice might find this of interest; the initiated, however, will learn nothing new. There is another fine collection of papers on simulation and stability analysis. Various simulation models are described which endeavour to investigate the effects of load representation on power system disturbance stability. Loads are for the most part in the papers simulated by static models with a range of voltage and frequency characteristics. Two types of marginally stable oscillation models are examined in the various expositions. One involves machine angles while the other focuses on excitation
140 'Appl. Math. Modelling, 1982, Vol. 6, April
system states. This should be sufficient to give the flavour of the papers included in this proceedings volume. For the most part, the papers are of value. (As in all such publications, there are a small, finite n u m b e r that would have best been omitted.) The volume should most properly be used as a reference. The papers, generally, contain concise summaries of the issue of interest but, more importantly, provide good references to other material in an area. Some papers in an effort to adhere strictly to the constraint on length are too brief to provide much information. A number of papers are written by individuals whlo do not communicate well in English (all of the papers are written in English or a variant thereof). As a result the contents are barely comprehensible. One particular oversight in the conference was the very slight attention paid to the impact that renewable energy sources (e.g., solar, biomass, photovoltaic) will have on power systems. The assessment of this is important for utilities, especially over the longer term. I would hope that future power system computation conferences would devote some time to this consideration.
Noel D. Uri
Case studies in mathematical modelling
(Ed. Bradley, R., Gibson, R. D. and Cross, M.) Pentech Press, London and Plymouth, 1981,167 pp., £14.00 The North East Polytechnics Mathematical Modelling and Computer Simulation Group held its inaugural conference, 'POLYMODEL 1', at Sunderland in May 1978. A second equally successful conference, POLYMODEL 2, was held at Teesside in May 1979. The proceedings of both conferences were published. This book is the outcome of POLYMODEL 3 held at Newcastle upon Tyne in May 1980. The editors have adopted a different format from that of the first two conference reports, and in this form the book should achieve a wider readership. Following an introduction which describes the modelling process with illustrations from blast-furnace performance analysis, the book presents six casestudies on such diverse topics as choosing a pick-up arm for a record player, deciding the correct diameter and spacing for rollers in a float-glass process, and determining the temperature distribution of meat during freezing or thawing.
Book Reviews
Each case-study presented includes a typical student-report, compiled by a team of modellers under workshop conditions, together with a critical assessment of the team's approach and a model solution prepared by the author. The book should appeal to any practitioner (including beginners) who wishes to gain further experience of modelling and to academics concerned with modelling-courses. The latter will not find in this a ready-made text-book but will find a generous stock of
material from which they can select cases to suit the needs of their students. The mathematical knowledge required is claimed to be no more than that of the average physical-science or engineering graduate and the actual level ranges from the elementary (the cosine rule and sine wave in the record-player problem) through the fairly familiar 9ordinary differential equations in the (ordinary differential equations in the float glass process problem) to the obscure (enthalpy and the Kirchhoff transform in the meat-freezing and
thawing problem). Barring a few minor syntax errors, the presentation is of a high standard, with clear diagrams and neatly laid out mathematical expressions. The consensus view at POLYMODEI. 1 was that it usually took three years to make a graduate mathematician into a modeller. This book should knock a week or two off that time!
22-23 April 1982
30 June-2 July 1982
25--27 August 1982
Thirteenth annual modeling and simulation conference
Computational methods and experimental measurements
Johannesburg, South Africa
R. Croasdale
CALENDAR Hydrotransport 8
Pittsburgh, USA
Washington DC, USA
W. G. Vogt, Modeling and simulation conference, 348 Benedum Engineering Hall, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA
Dr C. A. Brebbia, ISCME, 125 High Street, Southampton SOl 0AA, UK
12-14 July 1982 11-14 May 1982
6-9 September 1982
The mechanics of sediment transport
Istanbul, Turkey International conference on geothermal energy
Florence, Italy
Organizing Secretary, Hydrotransport 8, BHRA Fluid Engineering, Cranfield, Bedford MK43 0A J, UK
Prof. B. M. Sumer, Faculty of Civil Engineering, Istanbul Technical University, Istanbul, Turkey
Conference Organizer, Geothermal Energy, BHRA Fluid Engineering, Cranfield, Bedford MK43 0A J, UK
Period flow and wake phenomena
Berlin, Germany Prof. Dr.-Ing. E. Berger, HermannFtttinger-Institut fiir Thermo- und Fluiddynamik, Technische Universitgt Berlin, Strasse des 17 Juni 135, 1000 Berlin 12, Germany
9-13 August 1982 1-3 July 1982
1982 Annual transportation convention
Modelling and simulation
Pretoria, South Africa
Vallee de Chevreuse, France
The ATC Secretariat, c/o The National Institute for Transport and Road Research, PO Box 395, Pretoria 0001, Republic of South Africa
AMSE, 16 Avenue de Grange Blanche, 69160 Tassin la Demi Lune, France
12-15 September 1982
19-21 July 1982
1982 Design automation conference
Washington DC, USA Prof. K. M. Ragsdell, School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907, USA
19-21 August 1982 1982 Summer computer simulation conference
Denver, Colorado, USA Dr M. F. Anderson, Department of Electrical and Computer Engineering, University of Colorado, 1100 Fourteenth Street, Denver CO 80202, USA
Seventh symposium on operations research
13-17 September 1982
St Gall, Switzerland
International symposium on numerical methods in geomechanics
Prof. Dr H. Loeffel, Institut for Unternelunensforschung, Hochschule St Gallen, Bodanstrasse 6, CH-9000 St GaUen, Switzerland
Zurich, Switzerland Dr R. Dungar, c/o Motor-Columbus, Parkstrasse 27, Baden, Switzerland
Appl. Math. Modelling, 1982, Vol. 6, April
141