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Overview, current trends and latest results in estimating the effects of load modelling on power-system damping and stability

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EUROPEAN TRANSACTIONS ON ELECTRICAL POWER 1997年第2期7卷 107-113页

作者： Milanovic, JV [?]Jovica V. Milanovic (1967) received the Dipl.-Ing. (Elec.) and M.Sc. (Elec. Eng.) degrees from the University of Belgrade. Yugoslavia. in 1987 and I99 I respectively. One year he worked with “Energoproject-MDD”- Engineering and Contracting Co. in Belgrade as an engineer in designing power plants and substations. In late 1988 hejoined the Faculty of Electrical Engineering of the University of Belgrade first as an associate teaching assistant and then (since late 199 I) as teaching assistant at the Dept. of Power Converters and Drives. Between March 1993 and January 1996 he completed his Ph.D. at the University of Newcastle. Australia. at the Dept. of Electrical and Computer Engineering. Since February 1996 he is lecturer at the Department of Electrical Engineering and Computer Science at the University of Tasmania Austnlia. His major interests include synchronous machines and power system transients control and stability. (The University of Tasmania. Dept. of Electrical Engineering and Computer Science GPO Box 252-65 Hobart Tas 7001 Australia.Te1+61 362/262-753 Fax+61 369/262 136. e-mail: Jovica.Milanovic@eecs.utas.edu.au)

The paper presents the overview of load modelling for power-system damping and stability studies with main conclusions summarized from previous research. The attempt has been made to present a cross-section of the most exploited existing load models together with the most important conclusions drawn from their implementation in power-system stability programs. The current trends and latest results in the domain of damping of electromechanical oscillations in power systems are also presented. The effects of load dynamics on damping of electromechanical oscillations were analyzed on the basis of one of generic load models proposed in the past. The recent results further encourage investigation in this area and highlights the importance of proper load modelling.

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Modular secondary voltage control based on local information

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EUROPEAN TRANSACTIONS ON ELECTRICAL POWER 1997年第3期7卷 179-184页

作者： Gubina, F Curk, J [?]Prof. Dr. Ferdinand Gubina (1939) received the Diploma Engineer M.Sc. and Dr. Sc. dcgms from h e University of LjubljandSlovenia in 1963. 1969 and 1972. respectively. From 1963 he was with the “Milan Vidmd” Electroinstitute Ljubljana. He was heading the Power System Opention and Control Department. In 1970 he joined for one year the Ohio State University Columbus Ohio as a teaching associate. Since 1988 he has been professorat the University of Ljubljana. His main interests lie in the area of electric power system operation and control. He is men ber of SC 39 CIGRE.ParislFrance and president of the National CIGRE Committee. (University of Ljubljana Faculty of Electrical and Computer Engineering Tmska256 loo0 Ljubljanalslovenia. Phone: + 38 66 I I2646 29 Fax: +38 66 1 I2646 30. E-mail: gubina@lddees.fer.unilj.si)

A new concept of highly decentralized secondary voltage control is presented. The concept is based on secondary voltage controllers attacked to each reactive power source. The secondary controllers utilize only local information available from measurements at the generating bus and they act completely autonomously. To successfully attain information on the electrically close load bus behaviour describing their voltage profile, a group of fuzzy sets is derived based on intrinsic load node properties and statistics of their voltage deviations. They are used in the fuzzy decision process to yield new reference setting for primary voltage controllers. The tests results of proposed modular secondary control are presented for standard and non-standard networks. The efficacy of the new concept is demonstrated.

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Developing a prototype concurrent design tool for composite topside structures

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NAVAL ENGINEERS JOURNAL 1997年第3期109卷 279-290页

作者： Dirlik, S Hambric, S Azarm, S Marquardt, M Hellman, A Bartlett, S Castelli, V Steve Dirlik:began his career at the Naval Surface Warfare Center Carderock Division in 1981 as an aerospace engineer co-op student. He completed his bachelor of science degree in aeropace and ocean engineering from Virginia Polytechnic Institute and State University in 1985 and his master of science degree in aerospace engineering from the University of Maryland in 1990. Mr. Dirlik recently completed a master of science program in applied physics at The Johns Hopins University and currently works in the Radar Cross Section and Target Physics Branch of the Signatures Directorate at the Naval Surface Warfare Center Corderoke Division. He has worked on Navy low observable programs since 1990. Stephen Hambric:is a research associate at the Applied Research Laboratory at The Pennsylvania State University. He received his B. S. and M.S. degree in mechanical engineering from Virginia Polytechnic Institute and State University and his D. Sc. in mechnical engineering from the George Washington University. He has worked on several computer aided multidiscikplinary design and optimization projects over the years including an automated propeller design system and a structural acoustic optimization capability. Dr. Shpour Azarm:is currently working as an associate professor with the Design and Manufacturing Group of the Department of Mechanical Engineering at the University of maryland at College Park. Dr Azarm's expertise is in the areas of optimization-based designed and concurrent design and optimization of multidisciplinary systems. He was a consultant at Black & Decker Corporation (summer 1996) and worked as a Navy senior summer faculty fellow (summer 1995) and a NASA summer faculty fellow (summer 1994). He was a visiting scientist at NASA Langley Research Center for Multidisciplinary Analysis and Applied Structural Optimzatiom at the University of Siegen in Germany (spring 1992) and the Design Institute of the Technical University of Denmark (summer 1990). Dr Azarm was an associate technical editor of the ASME Jour

A prototype concurrent engineering tool has been developed for the preliminary design of composite topside structures for modern navy warships. This tool, named GELS for the Concurrent engineering of Layered Structures, provides designers with an immediate assessment of the impacts of their decisions on several disciplines which are important to the performance of a modern naval topside structure, including electromagnetic interference effects (EMI), radar cross section (RCS), structural integrity, cost, and weight. Preliminary analysis modules in each of these disciplines are integrated to operate from a common set of design variables and a common materials database. Performance in each discipline and an overall fitness function for the concept are then evaluated. A graphical user interface (GUI) is used to define requirements and to display the results from the technical analysis modules. Optimization techniques, including feasible sequential quadratic programming (FSQP) and exhaustive search are used to modify the design variables to satisfy all requirements simultaneously. The development of this tool, the technical modules, and their integration are discussed noting the decisions and compromises required to develop and integrate the modules into a prototype conceptual design tool.

关键词： Warships

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Local positioning system by means of enclosing signal field

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SENSORS AND ACTUATORS A-PHYSICAL 1996年第1-3期54卷 457-463页

作者： Ohyama, S Kobayashi, A [a]Department of Control and System Engineering Faculty of Engineering Tokyo Institute of Technology 2-12-1 O-okayama Meguro-ku Tokyo 152 Japan

This paper deals with a position-measurement system which can be shared by multiple robots. This system can be applied to multiple automated vehicles working together, to robots working in a wide and open field, to Right systems and so on. We solve this problem by using the concept of an 'advanced active sensing system', and in practice, we propose an 'enclosing signal field' for two-dimensional position measurement. In this paper, we consider the generalized location of the signal-sending. devices and multiple sensors. Also, precise measurement using both the adjustment of the luminance ratio and initial phase shifting is presented. First, we propose a way to construct the enclosing signal field for multiple observing points, and consider the properties of this field by analysing the measurement equation. Next, we apply this field to precise position measurement using the zooming technique. Finally, a multiple zooming system is also proposed.

关键词： local positioning system position measurement signal field active measurement

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Effect of calcium chloride on sodium alginate microbubbles as ultrasound contrast agent

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JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 1996年第5B期35卷 3152-3155页

作者： Soetanto, K Chan, M Okujima, M Toin Human Science and Technology Center (HUSTEC) Department of Control and System Engineering Faculty of Engineering Toin University of Yokohama 1614 Kurogane-cho Aoba-ku Yokohama 225 Japan

In order to stabilize microbubbles without coating layers to be used as ultrasound contrast agent, the viscosity of the liquid for storage has to be increased. Sodium alginate is a material which forms viscous liquid when its powder is dissolved in water. The viscosity may vary from 1 cP to about 100 cP when the amount of material used is increased from 0.1% to 1%. However, the viscosity is still not enough to make stable microbubbles which can be stored for over several weeks. In this paper, by adding calcium chloride to the sodium alginate solution, a gel-type solution is produced which has a high viscosity capable of holding microbubbles for a long time. By measuring the viscosity of the sodium alginate solution and the solution with calcium chloride solution added, it is known that the solution is changed from a Newtonian liquid to a non-Newtonian liquid when calcium chloride solution is added. Since the attenuation coefficient of microbubble dispersion is proportional to title number of microbubbles, the disappearance of microbubbles lowers the attenuation coefficient. Therefore, in this study the attenuation coefficient is used as an estimating parameter for the lifetime of microbubbles.

关键词： microbubbles sodium alginate calcium chloride viscosity lifetime ultrasonic attenuation

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Acoustic properties of surfactant microbubbles in relation to their lifetime in vitro as determined by diffusion

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JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 1996年第5B期35卷 3148-3151页

作者： Chan, M Soetanto, K Okujima, M Toin Human Science and Technology Center (HUSTEC) Department of Control and System Engineering Faculty of Engineering Toin University of Yokohama 1614 Kurogane-cho Aoba-ku Yokohama 225 Japan

In this study, to make microbubbles less than 10 mu m and to extend their lifetime, sodium laurate is chosen as the material for the coating of microbubbles. In studies of ultrasound contrast agents, the authors are the first to report on the use of sodium laurate as the material for manufacturing the microbubble contrast agent. In addition, the method of producing microbubbles using a syringe is proposed. Using sodium laurate and the syringe method, microbubbles with diameter less than 10 mu m are produced. From the result of simulation, it is found that the dissolved gas concentration in the solution surrounding microbubbles plays an important role in determining microbubble lifetime. Microbubbles without coating are calculated to have a lifetime of less than 1 min when the dissolved concentration of gas is about 90%. On the other hand, the lifetime of microbubbles made from sodium laurate is about 5 min longer than the calculated lifetime. Therefore, it is hypothesized that when the dissolved gas in the solution is above a certain level, the mechanism governing annihilation of microbubbles is the dissolution of the surfactant coating layer into the solution, instead of the diffusion of gas from the microbubbles. Since the dissolution time of surfactants is longer than the dissolution time of gas, the lifetime becomes longer.

关键词： ultrasound contrast agent microbubble surfactant sodium laurate lifetime gas concentration attenuation

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Motion segmentation in RGB image sequence based on stochastic modeling

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IEICE TRANSACTIONS ON INFORMATION AND systemS 1996年第12期E79D卷 1708-1715页

作者： Kurianski, A Agui, T Nagahashi, H Department of Information Processing Interdisciplinary Graduate School of Science and Engineering Tokyo Institute of Technology Midori-ku Yokohama-shi 226 4259 Nagatsuta Japan Department of Control and System Engineering Faculty of Engineering Toin University of Yokohama Aoba-ku Yokohama-shi 225 1614 Kurogane-cho Japan

A method of motion segmentation in RGB image sequences is presented in details. The method is based on moving object modeling bq a six-variate Gaussian distribution and a hidden Markov random field (MRF) framework. It is an extended and improved version of our previous work. Based on mathematical principles the energy expression of MRF is modified. Moreover, an initialization procedure for the first frame of the sequence is introduced. Both modifications result in new interesting features. The first involves a rather simple parameter estimation which has to be performed before the use of the method. Now, the values of Maximum Likelihood (ML) estimators of the parameters can be used without any user's modifications. The last allows one to avoid finding manually the localization mask of moving object in the first frame. Experimental results showing the usefulness of the method are also included.

关键词： hidden MRF modeling RGB space multivariate Gaussian distribution motion segmentation

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Theory and characteristics of novel variable reluctance 1X resolver

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ELECTRICAL engineering IN JAPAN 1996年第5期116卷 128-137页

作者： Ishizaki, A Takasaki, K Shimomura, S Masaki, K Kitazawa, K Tokyo Denki University The Polytechnic University Tamagawa Seiki Co. Ltd. [?]Graduated in 1948 from the Department of Electrical Engineering Tokyo Institute of Technology and received his Dr. of Eng. degree from the same university. He joined Meidensha Corporation in April 1948. He has engaged in research development and design of rotating machines. He became a General Manager of the First Division at Research Laboratory in 1965 a Plant Manager of Ohsaki Works in 1974 and a Director in 1977. He became a Professor in the Department of Electrical Engineering Nagaoka University of Technology in 1981. He has been a Professor on the Faculty of Engineering Tokyo Denki University since 1990. He is engaged mainly in the analysis of rotating machines using finite element method as well as research on the optimization of the rotating machines and their control as a system. He is a member of IEEE.

Although brushless resolvers have been used widely as angular position transducers, they are expensive due to their intricate construction, involving a rotary transformer to supply the exciting coils wound on the rotor poles with the current. It is shown theoretically in this paper that the resolver without rotary transformer or brushes can be realized by simple construction, which consists of the stator core with both 4-poles exciting windings and 2-poles output ones and the rotor core carrying no windings. In this resolver the rotor core has minimum gap at one side and a maximum gap at another side of the diameter. It is characterized by an outer surface form that makes the fluctuation part of gap permeance very in proportion to cos theta, where theta represents the angular position of a point in the air gap with respect to the origin on the rotor, the point of minimum air gap. The method determining the rotor form to embody the afore-mentioned gap permeance variation is also shown. It has been confirmed not only by simulation but also experiment that the 2-phase output voltages of a model designed based on the theory have sinusoidal waveforms with very small harmonic contents. Moreover, the rotor position detected by processing the output voltages through the conventional resolver/digital converter was within acceptable engineering accuracy.

关键词： resolver VR type rotating position detection optimal rotor shape electrical error

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Modelling, Adaptive, Neural and Fuzzy control of Coal Power Plants 1

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IFAC Proceedings Volumes 1995年第26期28卷 347-352页

作者： Petr Pivoňka Department of Automatic Control and Instrumentation Faculty of Electrical Engineering and Computer Science 61266 Brno Božetěchova 2 Czech Republic

At the preparatory stage for connecting the Czech power systems to the West European UCPTE system, corrections for frequency must be included in the output power control, i.e. the primary control must be introduced. The result of the detailed analysis was a model of primary output power control of the block and a new power system control of Czech coal power plants. In the new power system control, an adaptive or robust controller will be used for operation stabilisation

关键词： Power system control adaptive control neural control fuzzy control fuzzy PID controllers self-tuning control neural nets

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A neural network recognition system for machine printed characters on coils

A neural network recognition system for machine printed char...

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Conference Record of the IEEE Industry Applications Society Annual Meeting (IAS)

作者： T. Yanagita T. Tanaka A. Toshima Kashina Steel Works Sumitomo Metal Industries Limited Japan Kokura Steel Works Sumitomo Metal Industries Limited Japan Instrumentation System & Development Department Sumitomo Metal Industries Control Engineering Corporation

A new system applying the inherent pattern recognition capability of a neural network has been developed for the task of recognizing machine printed alphanumerics on steel coils. The system has been used in the newly constructed No.2 Kashima cold strip mill (2KCM) since April 1993 and has contributed to fully automatic operation in the 2KCM. The system is 100% accurate in detecting coils that have been transported by mistake, and can do so within a few seconds.

关键词： Neural networks Character recognition Coils Milling machines Strips Steel Metals industry Automatic control control systems Computer displays

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