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Time-varying loads in electric power systems: Power input, equivalent circuit elements, and disturbances

EUROPEAN TRANSACTIONS ON ELECTRICAL POWER 1997年第1期7卷 5-11页

作者： Knoop, M Kohle, S [?]Michael K. F. Knoop(1965)received a Dipl.-Ing. degree in electrical engineering from Universit?t Knrlsmhe. Germany. and a Dr.-hg. degree from Universit?t der Bundeswehr Hamburg Germany. He now works with the automation department of Betriebs for schungsinstitut (BFI) mainly in the tield of modelling and control of electric xc furnaces. His interests also include dynamic systems and control theory. (Betriebsforschungsinstitut. VDEh-lnstitut fur angewandte Forschung GmbH. Postfach I05 145. D-40042 Dusseldorf Tel+491 I1/6707-385 Fax +49211/6707-3 10)

Time-varying electric loads, fluctuating around their nominal point, cause fluctuations also of current and power. The mean phasors of current and complex power differ from their nominal values, which results in a deflection of mean power input. A transformation to a time-invariant equivalent circuit is introduced representing the mean values of voltage, current and power. The variances on the other hand contribute equations for a second phenomenon of fluctuating lends: the generation of disturbances in the power supply system. Results for both phenomena are derived for single-phase lends, validated by Monte-Carlo simulations, and generalized to three important kinds of three-phase bonds. Measured data from an electric arc furnace illustrate the application of ideas.

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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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A knowledge-based system for solving multi-objective assembly line balancing problems

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INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH 1996年第9期34卷 2533-2552页

作者： Malakooti, B Kumar, A [a] Department of Systems Control and Industrial Engineering Center for Automation and Intelligent Systems Research Case Western Reserve University Cleveland OH USA

This paper presents design-and-development details of a knowledge-based system that solve multi-objective assembly line balancing problems to obtain an optimal assignment of a set of assembly tasks to a sequence of workstations. Assembly line balancing problems arise in high-volume production systems with a significant regularity. The formulation and solutions currently employed by managers and practitioners usually aims at optimizing one objective (e.g., number of work stations or cycle time), thus ignoring the multi-dimensional nature of the overall objectives of the manager. Furthermore, in practice ALBPs are ill-defined and ill-structured, making it difficult to formulate and solve them by mere mathematical approaches. The knowledge-based system multi-objective assembly line balancing approach, presented in this paper, addresses these needs. This paper presents a knowledge-base multi-objective approach to assembly line balancing problems. It demonstrates how such a system can be constructed and how a variety of assembly line balancing methods can be used in a uniform structure to support the decision maker (DM) to formulate, validate the formulation, generate alternatives, and choose the best alternative. Its capabilities include: (1) Elimination of inconsistencies in the problem structure, (2) The use of multi-objective formulation of the problem, (3) A well-designed user-interface, (4) Pursuance of the overall objectives of the manager via a new mechanism, (5) Development of several efficient alternatives, consistent with the user-specified constraint structure, providing the decision maker with a larger number of choices, and, (6) An approach for ranking and prioritizing alternatives consistent with the decision-maker's preferences.

关键词： Production control

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Model predictive control algorithms for systems with slow sampled outputs

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IEE PROCEEDINGS-control THEORY AND APPLICATIONS 1996年第6期143卷 551-556页

作者： Mao, KZ Chai, TY Research Center for Automation Northeastern University People's Republic of China Department of Automatic Control and Systems Engineering University of Sheffield United Kingdom

Many practical systems involve sensors that provide signals at slow sample rates. Guaranteeing the intersample performance is a fundamental problem in controlling such systems. Two multirate model predictive control schemes are presented as solutions to this problem. In the first control scheme, intersample responses are estimated and used as compensation for the missing measurements of the controlled output. This scheme can therefore operate at the desired fast rate. The second scheme updates the control action at the slow rate that the output is sampled, but it is different from conventional techniques. This scheme finds intersample responses using a modified Z transform, and produces the control variable by optimising a performance index that accounts for both sample and intersample behaviour. Numerical simulations demonstrate that the two multirate algorithms exhibit improved time responses compared to the conventional approach.

关键词： digital control predictive control algorithms

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Avoidability measure in moving obstacle avoidance problem and its use for robot motion planning

Avoidability measure in moving obstacle avoidance problem an...

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Proceedings of IEEE/RSJ International Conference on Intelligent Robots and systems. IROS '96

作者： Nak Yong Ko Bum Hee Lee Department Control and Instrumentation Engineering Chosun University Kwangju South Korea Department Control and InstrumentationEngineering Automation and Systems Research Institute Seoul National University South Korea

ISBN: (纸本)078033213X

This paper presents a new solution approach to moving obstacle avoidance problem of a robot. A new concept avoidability measure (AVM) is defined to describe the state of a pair of a robot and an obstacle regarding the collision between them. As an AVM, virtual distance function (VDF) is derived as a function of the distance from the obstacle to the robot and outward speed of the obstacle relative to the robot. By keeping the virtual distance above some positive limit value, the robot avoids the obstacle. In terms of the VDF, an artificial potential field is constructed to repel the robot away from the obstacle and to attract the robot toward a goal location. At every sampling time, the artificial potential field is updated and the force driving the robot is derived from the gradient of the artificial potential field. The suggested algorithm drives the robot to avoid moving obstacles in real time. Since the algorithm considers the mobility of the obstacle as well as the distance, it is effective for moving obstacle avoidance. Some simulation studies show the effectiveness of the proposed approach.

关键词： Motion measurement Robot motion Motion planning Hidden Markov models Robotics and automation Automatic control Instruments Sampling methods Vehicle dynamics Orbital robotics

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Application and comparison of alternative position sensors in high-accuracy control of an X-Y table

Application and comparison of alternative position sensors i...

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International Workshop on Advanced Motion control (AMC)

作者： M. Fischer M. Tomizuka Institute of Automatic Control Laboratory of Control Systems and Process Automation Technical University of Darmstadt Darmstadt Germany Department of Mechanical Engineering University of California Berkeley Berkeley CA USA

High-accuracy positioning is applied in a variety of modern computer-controlled machines. The achievable precision is not only determined by the mechanical properties of the systems but strongly depends on the utilized control algorithms and the quality of the sensor signals. The objective of this paper is to demonstrate how alternative position sensors influence the performance of a robust digital tracking controller consisting of a disturbance observer in the velocity loop, a feedback controller in the position loop, and a zero phase error tracking controller as feedforward controller. Two different sensor systems for an x-y positioning table are considered. While a digital encoder is attached to the actuating motor, a laser interferometer with a significantly higher resolution directly measures the position of the compliantly coupled table. The latter case represents a noncollocated system. After introducing the hardware setup, both the system identification and the controller design are briefly reviewed. The impact of the measurement device on the control performance and the optimal choice of the controller parameters are investigated in extensive experiments.

关键词： Mechanical sensors Velocity control control systems Sensor systems Tracking loops Optimal control Application software Mechanical factors Robust control Digital control

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Force optimization of multiple cooperating robots rigidly holding a common object using dual method

Force optimization of multiple cooperating robots rigidly ho...

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SICE Annual Conference

作者： Woong Kwon Bum Hee Lee Automation and Systems Research Institute Seoul National University Seoul South Korea Department of Control and Iiistrumentation Engineering Seoul National University Seoul South Korea

A new force optimization scheme of multiple co operating robots is explained. General formula tions of the force optimization problem are built into quadratic programming with linear equality and quadratic inequality constraints. This paper presents an algorithm for solving these general force optimiza tion problems using compact dual method, The proposed algorithm reduces the problem size considerably and makes the problem simpler. These features exhibit the efficiency of this technique compared with well-known other methods. Numerical examples for two cooperating PUMA robots using the proposed al gorithm and Nahon's algorithm are presented and comparison of the both methods are explained.

关键词： Optimization methods Robotics and automation Constraint optimization Torque Quadratic programming Robot programming Automatic control control systems Linear programming Friction

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FPGA-based implementation of Synchronous Petri Nets

FPGA-based implementation of Synchronous Petri Nets

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International Conference on Industrial Electronics, control and Instrumentation

作者： Naehyuck Chang Wook Hyun Kwon Jaehyun Park Control Information Systems Laboratory School of Electrical Engineering Seoul National University Seoul Department of Industrial Automation Engr Inha University Ichon South Korea

ISBN: (纸本)0780327756

This paper describes a flexible and systematic implementation method of Petri Nets that can be applied to high speed parallel control. This paper suggests a hard-wired implementation for a high frequency clock-driven system with little jitter. To implement Petri Nets with synchronous (clock-driven) digital circuits, a Synchronous Petri Net is proposed. The suggested implementation method is based on a regular cell-array such as FPGA (field programmable gate array). Radix-k Petri Net and Radix-k conversion are defined to solve technology mapping problem of FPGA that consists of k-size cells. Cell usage, cell utilization, cell complexity, and speed index are defined and derived, which are used for quantitative analysis and efficient design. To help the design process, necessary CAD tools such as design entry library, hard-macro library, and net-list converter are developed. The suggested method is demonstrated using Xilinx FPGA, and its operation is verified by computer simulations.

关键词： Petri nets Field programmable gate arrays Clocks Libraries control systems Frequency Jitter Digital circuits Process design Design automation

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Application of fuzzy logic technology for spatial load forecasting

Application of fuzzy logic technology for spatial load forec...

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IEEE PES Transmission and Distribution Conference and Exposition

作者： Mo-yuen Chow Hahn Tram Department of Electrical and Computer Engineering North Carolina State University Raleigh NC USA Systems Control-Distribution Automation ABB Power Transmission and Distribution Company Inc. Cary NC USA

ISBN: (纸本)0780335228

Utilities are required to provide reliable power to customers. In the design stages, utilities need to plan ahead for anticipated future load growth under different possible scenarios. Their decisions and designs can affect the gain or loss of millions of dollars for their companies as well as customer satisfaction and future economic growth in their territory. This paper proposes and describes the general methodology to use fuzzy logic to fuse the available information for spatial load forecasting. The proposed scheme can provide distribution planners other alternatives to aggregate their information for spatial load forecasting.

关键词： Fuzzy logic Load forecasting Power system reliability Costs Power system planning Geographic Information systems Economic forecasting Distributed computing Customer satisfaction Power generation economics

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Reliability evaluation of highly reliable computer control systems for energy generation, transmission and distribution

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EUROPEAN TRANSACTIONS ON ELECTRICAL POWER 1996年第2期6卷 111-118页

作者： Kochs, HD Dieterle, W Dittmar, E [?]Prof. Dr.-Ing. Hans-Dieter Kochs (1943) VDE is head of the Department of Computer Science and Information Processing Systems at the Gerhard Mercator-University of Duisburgl Germany. He received the Dip1.-Ing. degree in Electrical Engineering and the Dr.-Ing. degree from the RWTH Aached Germany in 1972 and 1976 respectively. From 1979 to 1991 he was system engineer and division leader in the areas of R & D of highly-reliable large-scale control and information systems (AEGIDaimler FAG-Kugelfischer). Since 199 1 he has been Professor at the University of Duisburg. His current R & D areas are reliability safety and fault tolerance of technical systems especially automation systems and hybridknowledge based systems including fuzzy-logic and neural networks. (Gerhard-Menxitor-University-GH Duisburg FB 71FG 10 Lotharstr. 1 D-47048 Duisburg T +49203/379-2204 Fax +49203I379-2205)

The paper presents the results of an application-based reliability study of distributed computer control systems with very high reliability demand, e.g. for supervision and control of power plants and energy distribution systems. A reliability classification scheme is presented and typical redundant control system structures are evaluated and classified due to their system reliability Special focus is placed on assessing the influence of the communication system on total system reliability.

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