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Power Engineering, 2001. LESCOPE '01. 2001 Large Engineering Systems Conference on

Date 11-13 July 2001

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Displaying Results 1 - 25 of 39
  • 2001 Large Engineering Systems Conference On Power Engineering [front matter]

    Page(s): i - vii
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    Freely Available from IEEE
  • 2001 Large Engineering Systems Conference On Power Engineering [front matter]

    Page(s): i - vi
    Save to Project icon | Request Permissions | PDF file iconPDF (269 KB)  
    Freely Available from IEEE
  • Load management and control of the photovoltaic (PV) system using fuzzy logic

    Page(s): 184 - 188
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1420 KB) |  | HTML iconHTML  

    This paper provides a fuzzy logic control scheme for PV power systems under faults and load disturbances. The classical model using microprocessors, power electronics and DC-DC converters can be made less complicated with the application of a fuzzy logic controller, which is robust and good for nonlinear systems. Inputs to the fuzzy logic controller are the optimal power tracked (using a genetic algorithm), the state of charge of the battery and the load current. The output controls the rate of current injection into the battery for energy storage or increases or decreases the load in priority order to match the optimal requirement. The fuzzy design scheme is developed around an in-house PV program using Matlab software. View full abstract»

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  • Author's index

    Page(s): 213 - 214
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    Freely Available from IEEE
  • Software engineering in power systems: practices and challenges

    Page(s): 25 - 30
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    This paper presents an overview of applying software engineering concepts in development of software for use in deregulated power markets. An overview of power system deregulation is presented and the importance of software requirements management and software testing, in particular, in the development of power systems software is underlined. Practices adopted for the purpose are enumerated. Sample illustrations for managing power software requirements and enhancing testing practices to improve software quality are also presented. Challenging issues related to power system software are briefly outlined View full abstract»

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  • Two digital filtering algorithms for fast estimation of symmetrical components in power system: a static estimation approach

    Page(s): 125 - 130
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (416 KB) |  | HTML iconHTML  

    This paper presents the application of two digital filters working together for fast estimation of the system symmetrical components. The three-phase unbalanced system is transformed into αβ-transformation. Using such a transformation, harmonics of order 3 and their multiples can be eliminated from the input signal. Having identified the two-phase voltage, the positive and negative sequence phase voltage can be calculated using a constant transformation matrix as well. The zero sequence is easily estimated by averaging the unbalanced three-phase voltage at any sample instant. The least error square algorithm is the parameter estimation algorithm used to identify the magnitude and phase angle of each sequence component from the available samples of the specified component View full abstract»

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  • A structured methodology for intelligent system selection in nuclear power industry applications

    Page(s): 44 - 48
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB) |  | HTML iconHTML  

    As the number of successful implementations of intelligent systems (ISs) to perform nonsafety related operations increases, so the desire has grown to assess the possibility for use of ISs to support safety related functions. This interest has been recognised by the nuclear industry who wish to determine if ISs can be successfully and reliably used for performing condition monitoring of critical data. Therefore, in order to test the applicability of ISs in the nuclear domain, it is necessary to create a structured development methodology that explains why and how development decisions have been made. At the top level of this IS development methodology, it has consequently been necessary to develop a generic IS selection methodology which can be applied to any relevant problem. This paper has presented a methodology, to aid a decision maker in choosing an appropriate intelligent system as the solution to a given problem. This methodology provides a formal framework for justification of the decisions made and provides the facility for traceability and subsequent justification of these decisions. This is therefore useful for nuclear power software applications where it is desirable to make well-planned and justifiable decisions when the IS is to be used in safety-related applications View full abstract»

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  • Power factor correction of single-phase and three-phase unbalanced loads using multilevel inverter

    Page(s): 131 - 138
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    This paper deals with power factor correction of single phase and three phase unbalanced loads using a multilevel inverter circuit. We propose the utilization of single phase, multilevel diode clamped voltage source inverters (VSI) with large capacitors for energy storage. Simulation and experimental results are presented View full abstract»

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  • An artificial neural network model for electrical daily peak load forecasting with an adjustment for holidays

    Page(s): 105 - 113
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (660 KB) |  | HTML iconHTML  

    This paper presents an artificial neural network model for daily peak load forecasting. The input variables of the model have been selected based on their correlation coefficients. The model uses only three input variables. In addition, a new technique for selecting the training vectors is introduced. Moreover, the model presents a unique adjustment algorithm to compensate the negative impact of holidays' forecasts. Also, the model uses an adjustment technique for Sundays and Mondays forecasts as these two days showed higher error than the rest of the weekdays. Nevertheless, the model is simple, fast, and accurate. The mean percent relative error of the model over a period of one year is 2.066% including holidays View full abstract»

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  • Challenges and opportunities facing electricity distribution utilities

    Page(s): 167 - 171
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (504 KB) |  | HTML iconHTML  

    UK electricity distribution utilities will be faced with a number of challenges and opportunities as a result of distributed generation appearing on their networks. It is argued that the current approach to distribution network design, which relies on network reinforcement practices, will not be conducive for designing networks in the future. Especially to take advantage of the opportunities while at the same time mitigating the challenges, network designers should be in a position to consider all solutions that can solve a particular design problem. This means that they should consider both network reinforcement and contemporary design solutions. Contemporary solutions include the wide range of power electronic controller devices on the market. A new framework is presented to facilitate the design of distribution networks in the future View full abstract»

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  • Voltage stability constrained VAr planning-a case study for New Zealand

    Page(s): 86 - 91
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    This paper discusses a VAr planning optimisation model that takes into account voltage stability constraint, and proposes an efficient solution algorithm to solve it. A contingency constrained optimal power flow (OPF) based model incorporating (static) voltage stability constraints is developed to analyse optimal VAr support decisions. Given a set of contingencies, the model performs the contingency ranking, decides optimal location and quantity of VAr support to simultaneously cover all the contingencies. DICOPT++, a state-of-the-art mixed integer nonlinear programming (MINLP) algorithm, is proposed to solve the model efficiently. The model is implemented for a 17 bus reduced New Zealand North Island system. The modal analysis is also conducted and the result is discussed View full abstract»

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  • An approach for optimal units start-up during bulk power system restoration

    Page(s): 190 - 194
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (388 KB) |  | HTML iconHTML  

    This paper describes an approach for unit start-up sequence determination during power system restoration. This approach is based on the backtracking search method, which determines the generating starting times to maximize the MWh load served over a restoration period and guarantee optimality of the start up sequence. The dynamic characteristics of different types of units and system constraints have to be considered. The shortest path, i.e., the path that requires the minimal number of switching actions, between the supplying unit and load is selected unless it is not feasible. Simulation tests, carried out on 39-bus New England test system, verify the effectiveness of the proposed method View full abstract»

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  • GENCOs portfolio management using “STRATEGIST” in deregulated power markets

    Page(s): 12 - 17
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (368 KB) |  | HTML iconHTML  

    STRATEGIST is a software package that is coded in FORTRAN and C++ for GENCOs' portfolio management in deregulated power markets utilizing COUGER which is a unit commitment software package coded in FORTRAN for profit maximization. STRATEGIST incorporates a probabilistic approach for the evaluation of composite reliability of generation, load forecast and fuel prices using different probability distributions. STRATEGIST analyses the risk in an uncertain power market. This package is to be used by GENCOs to maximize their profit as well as to hedge the GENCOs to against crucial loss of profit. A typical scenario for applying this package is a GENCO which tries to supply its native load and trade bilateral transactions and would be interested in determining the risk associated with different alternatives. STRATEGIST is designed based on a comprehensive analysis of various risks in a portfolio View full abstract»

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  • Location of FACTS devices for enhancing power systems' security

    Page(s): 162 - 166
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (432 KB) |  | HTML iconHTML  

    A stressed power system, either due to increased loading or due to severe contingencies, often lead to situations where the system no longer remains in the secure operating region. Under these situations, it is a primary objective of the operator to apply control action to bring the power system into a secure region. Any delay or unavailability of suitable control, and the system may become unstable. FACTS devices can play a very important role in power system security enhancement. Due to high capital investment, it is necessary to locate these devices optimally in the power system. In this paper, a suitable approach has been suggested based on the sensitivity analysis on FACTS device control parameters with respect to reduction in a real power flow performance index to enhance the security of the power system. The proposed approach has been illustrated on a sample system View full abstract»

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  • Simple power distribution load forecasting method based on fuzzy modelling

    Page(s): 93 - 97
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (472 KB) |  | HTML iconHTML  

    During the last three and a half decades various load forecasting methods have been created. However, these methods cannot forecast future loads in case of severe lack of data, when only few loads are measured in nonconsecutive years. This paper presents two simple methods developed specially to handle such a situation: a simple trending method and a method based on fuzzy modelling. Fuzzy modelling is carried out using a subtractive fuzzy clustering algorithm and recursive least-squares estimator. Both load forecasting methods are illustrated by a numerical example View full abstract»

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  • Modeling of legacy intelligent electronic devices for UCA based substation integration systems

    Page(s): 38 - 43
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (664 KB) |  | HTML iconHTML  

    Intelligent electronic devices (IED) are the standard protection and control equipment in today's substations. UCA2 based protection and control systems integrate devices that are designed to support the UCA object models. However, there is a huge installed base of legacy protection and control IEDs that are still going to be available for many years and will have to be integrated in UCA based systems. The paper describes in detail the complex object model of multifunctional legacy protection and control IEDs. The models are based on the existing UCA 2 documents (Generic Object Models for Substation and Feeder Equipment-GOMSFE). It presents the basic building blocks and their grouping in order to model such a protective device. The challenges of modeling different multifunctional legacy devices in a single gateway are discussed. The object-oriented approach to peer-to-peer communications for high speed protection and control functions and issues related to gateway based applications are covered in another section of the paper. They are based on Generic Object Oriented Substation Event (GOOSE) messages exchanged between protective relays connected to the substation LAN View full abstract»

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  • Intelligent engineering support for protection scheme design

    Page(s): 54 - 58
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (516 KB) |  | HTML iconHTML  

    This paper describes a research project focusing on the provision of 'intelligent' engineering support facilitating two major UK utilities in the design of complex protection schemes associated with electrical transmission networks. The development and functionality of the Engineering Design Knowledge Application System (DEKAS) is described within the paper. In addition, broader issues concerning the capture of design rationale for design re-use and the application of knowledge engineering techniques in the development of expert systems and the general promotion of knowledge management are explored View full abstract»

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  • Modelling and simulation of a PV-inverter-asychronous motor association in photovoltaic pumping systems

    Page(s): 146 - 151
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (180 KB) |  | HTML iconHTML  

    In this paper, we introduce a method of control and sizing of photovoltaic systems in stand alone PV pumping plants. This approach is based on the dynamic model of the PV-DC/DC inverter-asynchronous motor. The DC-DC converter ensures an impedance adaptation between the PV and the load and an optimal PV panel output power extraction. However, the DC/AC converter ensures a PWM control of the induction motor and a sinususoidal output signal. This methodology allows an optimal control and monitoring of continuous-continuous and continuous-alternative converters by calculating respectively the DC/DC cyclic ratio and the DC/AC frequency. Contrary to classic methods, this method, which is based on the parametric model of the PV system, leads to a best prediction of the the PV installation especially with load and climatic fluctuations View full abstract»

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  • Power cable on-line diagnosis using partial discharges ultra wide band techniques

    Page(s): 201 - 205
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (348 KB) |  | HTML iconHTML  

    A noninvasive ultra-wide band (UWB) partial discharge technique was employed in cable diagnosis of Mexico City underground distribution feeders. The technique presented here was applied to over 2000 joints, 400 terminals and thousands of meters of installed paper insulated impregnated cables rated at 23 kV. The technique allowed circuit classification according to electromagnetic field levels produced by partial discharges and recorded on each manhole with a joint along the circuits evaluated in 12 substations. The PD detection technique employs near field sensors working within the 80 MHz range and whose information is digitized and fed to a conventional PD digital detector, where a PD pattern is obtained. This pattern is correlated to the phase current by using an inductive sensor; therefore corona and interference problems could be disregard during measurements. To attain repetitive values, calibration was performed using a very fast pulse (less than 50 ns front) injected in a small cable loop. Results demonstrate a great signal to noise ratio, high selectivity and great noise discrimination. The large amount of measurements allowed the determination of limit values to differentiate areas in acceptable state from those requiring attention. Those results include detection of bad joints, cable deformation due to ducts collapse and damaged terminals, besides aged cable detection caused by overheating operation conditions. The results obtained had been confirmed by subsequent faults following the detection of very high levels of PD View full abstract»

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  • Steady state stability assessment using the bus impedance matrix

    Page(s): 153 - 157
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (452 KB) |  | HTML iconHTML  

    Power systems operations are undergoing changes, brought about primarily due to deregulation. Restructuring and interconnection of bulk power systems have made power system analysis much different than what it was earlier. All this, coupled with economic pressures, has made the present day power system an increasingly complex network, operating under stressed conditions, close to stability limits. Thus for present day power systems, voltage stability analysis has acquired predominant importance. This paper presents results of a method developed to assess the state of a system, from the viewpoint of voltage stability, after a certain load increase. Its unique feature is that it does not use any load-flow calculation at all. The concept of maximum power transfer at a node is used. This makes the method highly efficient in terms of computation time. Results are obtained for five test systems, and a comparison with the load flow calculations is presented View full abstract»

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  • Security assessment of DC zonal naval-ship power system

    Page(s): 206 - 212
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    Security assessment of naval-ship power system under different fault conditions is important for real time operation of naval-ship power system. The existing indices of security assessment did not incorporate the probability of disturbances: therefore this paper proposes a probabilistic security assessment index. As the naval ship architecture is integrated with DC zonal distribution, then a special power flow analysis is needed for the AC/DC IPS system. The paper addresses the incorporation of power flow analysis of naval-ship power system with power electronic devices, security analysis of architecture based on the expected contingency margin, and rank of different contingencies and their implication on system security. The approach is tested on one of the DC zonal naval ship power system topologies View full abstract»

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  • Standardization of technical losses in primary circuits of distribution for SCADA application

    Page(s): 172 - 176
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    The technical losses have taken importance since they represent economic damage for the companies. This to motivate from the different electrical distribution entities to undertake reduction strategies within a technical-economic context with you watch to improve the profitability and quality of service, to fulfil this objective is outlined a strategy of control and reduction of technical losses using technical of computation, statistics and control SCADA. Also it is developed an application that consists in the comparative analysis of all the digitized circuits of an electrical distribution net in base to standard of losses to be established. To accomplish the standardization were executed three phases, the first phase of data and recognition summary of the net. The simulations phase (in the program PSSU) and finishes it categorization phase, using statistic methods (multivariable analysis and segmentation) View full abstract»

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  • Supporting distance engineering education is greatly needed

    Page(s): 69 - 72
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    Academia has had enough modeling efforts and enough pilot projects of distance learning. What is needed now is long-term, sustaining efforts that truly can grow and be a substantial part of the education business. Some places are doing that, and others are struggling with it, but distance learning is certainly headed in that direction. Colleges have a long way to go before they get the support at a level that will help organizations learn enough to create sustaining programs. For distance learning to succeed, it has to have institutional reward systems that reflect distance-learning activity View full abstract»

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  • Simulating the impact of mergers on wholesale electricity prices

    Page(s): 18 - 23
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    This paper evaluates the impact of mergers of electricity generation companies on wholesale electricity prices. A spatial gaming model, with the Cournot-Nash strategy, is used for the evaluation. The proposed merger evaluation method has certain advantages over the traditional HHI index for measuring potential market power of generators. Case studies are provided to illustrate the use of the model View full abstract»

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  • The use of a multi-agent paradigm in electrical plant condition monitoring

    Page(s): 31 - 36
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    Electrical utilities need to operate their equipment closer to their design limits and require to extend their operating life through automatic condition monitoring systems. This paper introduces a multi agent paradigm for data interpretation in electrical plant monitoring. Data interpretation is of significant importance to infer the state of the equipment by converting the condition monitoring data into appropriate information. The vast amount of data and the complex processes behind on-line fault detection indicate the need for an automated solution. The classification of partial discharge signatures from gas insulated substations, as a result of applying different artificial intelligence techniques within a multi agent system, is described in this paper. A multi agent system that views the problem as an interaction of simple independent software entities, for effective use of the available data, is presented. The overall solution is derived from the combination of solutions provided by the components of the multi-agent system. This multi-agent system can employ various intelligent system techniques and has been implemented using the ZEUS Agent Building Toolkit View full abstract»

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