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Power Delivery, IEEE Transactions on

Issue 4 • Date Oct 1996

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Displaying Results 1 - 25 of 50
  • Minimum cost analysis of feeder routing in distribution system planning

    Page(s): 1935 - 1940
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    A new approach for optimal network routing in distribution system planning is presented in this paper. The distribution network routing planning problem is formulated as a nonlinear constrained, nondifferentiable optimization problem. The main objective is to minimize the total cost which is the summation of reliability costs, feeder resistive loss, investment and maintenance costs. Simulated annealing, which is a general purpose combinatorial optimization algorithm, is used to obtain a global optimum solution of the problem View full abstract»

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  • Development of a thyristor valve for next generation 500 kV HVDC transmission systems

    Page(s): 1783 - 1788
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    A high voltage thyristor valve is the basic component of an HVDC transmission system. Development of a 500 kV valve for next generation HVDC transmission systems is described. First, the power loss of the valve is analyzed to decide a reasonable wafer size for the light-triggered thyristor. From these results, a six inch diameter wafer size is selected. A light-triggered thyristor, with ratings of 8 kV and 3.5 kA, is developed using the six inch wafer. The design of the valve employing the thyristor and test results with a prototype valve prove that a 500 kV valve can be realized by this design method View full abstract»

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  • An assessment of the reliability of in-service gapped silicon-carbide distribution surge arresters

    Page(s): 1789 - 1797
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    Although gapped silicon carbide arresters are no longer purchased by electricity authorities, they still form the majority of the very large number of distribution arresters in service in Australia and many other countries. Most of the arresters of this type are now over ten years old and many are much older. So the question must be asked-what is to be done with this ageing and outdated class of arresters? Extensive Australian studies in the 1960s had revealed that internal degradation resulting from inadequate seals was the predominant cause of failure of gapped silicon carbide arresters. This paper describes the results of a recent investigation. Electrical testing showed that after about 10 years of service, there is a marked upturn in the number of arresters with unsatisfactory insulation resistance, and after about 13 years of service, a marked upturn in the number of arresters with reduced power frequency sparkover level. Inspection of the internal components of dismantled arresters confirmed that the likelihood of significant degradation increased markedly with years of service, and was evident in almost 75% of arresters with 13 years or more of service. The authors therefore recommend that all gapped silicon carbide arresters with 13 or more years of service be progressively replaced by modern metal oxide arresters View full abstract»

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  • Long term accelerated aging tests on distribution cables under wet conditions

    Page(s): 1695 - 1701
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    Two accelerated aging test procedures are proposed for use on solid dielectric extruded distribution cables under wet conditions. One test method is a fixed time duration test in which the degree of cable specimen aging is assessed in terms of breakdown tests, while the other test method is a time to breakdown test in which the cable specimens are voltage stressed until failure ensues View full abstract»

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  • A new closed loop control method for HVDC transmission

    Page(s): 1955 - 1960
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    The paper presents a new closed loop control method which uses information locally available at each power converter station and combines and coordinates control possibilities with the objective of improving the dynamic behaviour of HVDC transmission networks during fault recoveries and disturbances around their operating points View full abstract»

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  • An experimental study of acoustic vibration effects in optical fiber current sensors

    Page(s): 1702 - 1706
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    This paper presents experimental results comparing the susceptibility of two different optical fiber current sensors to environmental acoustic vibrations. Of the two sensors that are tested, one employs a uni-directional current detection scheme, and the other a bi-directional in-line Sagnac interferometer. Acoustic vibrations are applied to various optical components of the two different types of current sensors View full abstract»

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  • DC dielectric characteristics and conception of insulation design for DC GIS

    Page(s): 1776 - 1782
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    In order to discuss the dielectric performance of DC GIS, the flashover characteristics of gas-insulated bus were studied under conical- and disk-type spacers. The test involves the investigation on effect of electrification for charge to be accumulated in spacers and the effect of metallic particles. As the result, it was found that the dielectric characteristics of conical-type spacer are better than disk type. Moreover, the dielectric performance of DC GIS is more affected by the characteristics of coaxial electrode system than spacer surface with regard to metallic particle. On the basis of the results of these tests, this report presents the conception of insulation design for DC GIS View full abstract»

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  • Prediction of core saturation instability at an HVDC converter

    Page(s): 1961 - 1969
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    Core saturation instability has occurred on several HVDC schemes resulting from interactions between second harmonic and DC quantities (voltages and currents) on the AC side of the converter and fundamental frequency quantities on the DC side of the converter. The instability can be reinforced by unbalanced saturation of the converter transformers. The paper presents an analytical method which can be used to quickly screen AC and DC system operating conditions to predict where core saturation instability is likely to occur. Analytical results have been confirmed using the digital transients simulation program PSCAD/EMTDC View full abstract»

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  • The smoothing transformer, a new concept in DC side harmonic reduction of HVDC schemes

    Page(s): 1941 - 1947
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    Direct connection schemes have been a subject of recent investigation, offering operational flexibility and substantial reductions in AC components. In these schemes, the use of active DC filters has been suggested to replace the conventional tuned passive filter design. This paper presents the smoothing transformer as a new means for reducing DC harmonics at characteristic and noncharacteristic frequencies using only passive components. A realistic smoothing transformer design is examined using the New Zealand HVDC power system operating in the direct connection mode. The steady-state and transient performance of the smoothing transformer design is compared with that of the existing DC smoothing reactor and filter bank View full abstract»

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  • Transmission towers inventory

    Page(s): 1842 - 1852
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    Transmission towers for major power lines constitute a critical component because it is undesirable to lose any major transmission lines for longer than a few weeks. Since tower fabrication cannot be accomplished quickly on-demand, it is important to hold an adequate inventory of transmission towers. This paper discusses a statistical procedure to analyze failure data and estimate inventory requirements for transmission towers, using a homogeneous Poisson process model View full abstract»

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  • Development and field test results of the AC 275 kV compact filter

    Page(s): 1707 - 1712
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    The AC filters of an HVDC converter station usually require a large installation space and are sensitive to seismic activity due to using an air-insulation platform. As a solution to these problems, we have developed compact filters in which all energized parts are enclosed. As a result, the installation space is one-third of the platform type and seismic performance considerably improves. After the field tests were conducted. These filters were put in service in May, 1992 View full abstract»

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  • DC side filters for multiterminal HVDC systems

    Page(s): 1970 - 1984
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    Multiterminal HVDC power transmission systems present challenges in the specification and design of suitable DC side filtering. This document examines the existing experience and addresses the particular technical problems posed by multiterminal systems. The filtering requirements of small taps are discussed, as is the potential use of active filters. Aspects of calculation and design are considered and recommendations made to guide the planners and designers of future multiterminal schemes View full abstract»

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  • Impact of shunt capacitor banks on substation surge environment and surge arrester applications

    Page(s): 1798 - 1809
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    The introduction of high voltage shunt capacitor banks on a power system can result in a number of overvoltage problems that tend to be associated with capacitor switching. The paper describes how proper application of surge arresters near a shunt capacitor bank requires careful analysis of the power system, the switching devices and their arrangements, the insulation level of nearby equipment, the type of grounding and the arrester energy dissipation duty View full abstract»

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  • The application of model based reasoning within a decision support system for protection engineers

    Page(s): 1748 - 1754
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    This paper discusses model-based reasoning applied to power network protection system performance analysis. Appropriate modelling and reasoning methodologies are indicated, and their advantages considered. The necessity of incorporating protection system performance analysis within a decision support system (DSS), designed for electric utility protection engineers, is presented. Alarm processing and fault diagnosis are demonstrated as further requirements of the DSS for protection engineers, within which knowledge-based reasoning and model-based reasoning are combined to provide the overall functionality required View full abstract»

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  • Synchronized solution of power electronics system equations using flexible MODELS component connected to the EMTP

    Page(s): 1868 - 1873
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    The oscillations from the trapezoidal rule of integration following discontinuity and the one-time-step error from separate EMTP and TACS (or MODELS) simulations are the numerical stability and accuracy problems found in the transient study of power electronics systems using EMTP. This paper presents the technique of the synchronized solution of power electronics system equations. The proposed technique implements efficient and numerically stable approaches to model the switching circuit and control system as a MODELS component. This MODELS component is connected directly to the EMTP to avoid the one-time-step delay. Therefore, the numerical oscillations and one-time-step error in standard EMTP simulation can be eliminated View full abstract»

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  • Assessment of basic contamination withstand voltage characteristics of polymer insulators

    Page(s): 1895 - 1900
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    An artificial contamination method for hydrophobic polymer insulators has been developed which can provide a uniform contaminant layer, similar to that found in nature, without either damaging the polymer surface or by adding any chemical agent to the conventional contamination slurry. Using this method, the basic contamination withstand voltage characteristics of polymer insulators were investigated compared with those of porcelain insulators. The results show that although hydrophobic polymer insulators generally have excellent contamination withstand voltage characteristics, critical reduction of withstand voltage sometimes occurs under rapid and heavy wetting and contamination conditions View full abstract»

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  • Post-measurement processing of electric power quality data

    Page(s): 1853 - 1859
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    This paper addresses the issues of post-measurement processing of data collected in a power quality assessment study. Three broad types of post-measurement processing objectives are considered: to enhance accuracy; to estimate data; and to reduce the volume of the collected data. The methods used to enhance accuracy are bad data identification and rejection. Averaging is discussed as a method to “filter” measurement error. The methods used for data estimation are state estimation techniques in both the time and frequency domain. The methods used to reduce the volume of the collected data are based on the calculation of marginal and conditional probabilities and expectations. The integrated use of these techniques in an instrumentation system for power quality assessment is discussed. The main suggested application is for the measurement of harmonics View full abstract»

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  • A restoration aid expert system for distribution substations

    Page(s): 1765 - 1770
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    This paper presents a practical restoration aid expert system for 154 kV distribution substations. The proposed expert system has a topology-based simple structure and utilizes basic rules suggested by the Korean electric power company including heuristic rules, topology identification rules and search rules to generate switching sequences for feasible restoration processes. In this paper, the general system structure as well as rules and data representations are discussed. The expert system is realized using an HP9000 workstation. X-window and Motif shells are used for the user-friendly GUI. The system has been tested in a practical sub-control center as a part of an intelligent fault diagnosis and restoration aid system to assist the decision making of SCADA operators View full abstract»

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  • High power switch mode linear amplifiers for flexible AC transmission system

    Page(s): 1993 - 1998
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    The pulse width modulation (PWM) technique has been proposed for the force-commutated shunt and series VAr controllers and unified power flow controllers in flexible AC transmission systems. The PWM converters can be operated as linear amplifiers of constant gain so that linear control system theory can be brought to bear more easily when applying feedback controls. For example, pole-placement and active filtering have been successfully applied in laboratory models. This paper is written as a tutorial describing the stages of signal processing: modulation, amplification and demodulation, without reference to power electronics since the solid-state switches are modelled as ON-OFF switches View full abstract»

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  • Simulation of non-linear and switching elements for transient analysis based on wave digital filters

    Page(s): 2042 - 2048
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    A previous paper introduced the use of wave digital filters as a basic building block for power system simulation, particularly suitable for real-time applications. This paper stresses the simulation of nonlinear and switching elements, emphasizing the advantages of the wave filters implementation. The digital structure is maintained even when nonlinear components change their characteristics or power electronic devices switch their states. As a very important by-product, the suppression of numerical oscillations related to the trapezoidal rule is achieved in a rather simple way, with no effects on simulation results View full abstract»

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  • Taking environmental constraints into account in the planning of the extra high voltage transmission network; EDF's approach

    Page(s): 1901 - 1906
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    As EDF is experiencing increasing difficulties in developing its transmission network, the time may have come to reconsider the projects selection method. In this paper, the authors point out that the currently used method essentially relies on a classical discounted balance criterion. They then present a new method which takes into account the impact of a project on the environment, by considering an environmental risk which may jeopardize the project's success. This method helps to evaluate the probability that each possible route of each project will be carried through. A simple probability computation then allows the derivation of a global comparison of the eligible projects on the basis of an expected discounted balance criterion. Experiments now in progress will help to decide upon this method's efficiency in the context of its operational use View full abstract»

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  • Frequency relaying based on instantaneous frequency measurement [power systems]

    Page(s): 1737 - 1742
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    A frequency relay capable of under/over frequency and rate of change of frequency measurements has been implemented on a digital signal processor using an instantaneous frequency measuring algorithm. Careful attention to the filtering aspects of the relay is needed under dynamic conditions due to frequency modulation of the input signal. An algorithm for avoiding unwanted relay operation due to impulsive changes in the input signal is presented. Results are shown for simulated tests using computer-based relay testing equipment, and for overloads on a micromachine power system simulator View full abstract»

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  • Improving feeder voltage calculation results with telemetered data

    Page(s): 1914 - 1920
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    A method that uses uncertain network data, load distribution information and telemetered data for feeder voltage profile calculation is proposed in this paper. In the proposed method, data involved in the calculation are represented by using fuzzy numbers. All possible feeder voltage solutions within bounds obtained from fuzzy arithmetic are considered. The mean values of the obtained intervals are useful for power system operation planning, and lower and upper bounds can be used to alert dispatchers for possible system deterioration. Measurements are included in the calculation to reduce the uncertainty of the obtained results. The voltage calculation method is used to evaluate the measurement configuration and a meter placement scheme is proposed to select the locations of new meters from the standpoint of minimizing the uncertainties of the calculated voltage profile View full abstract»

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  • Simulator demonstration of the interphase power controller technology

    Page(s): 1985 - 1992
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    The paper reports on a simulator demonstration of the interphase power controller (IPC) technology. The simulator models developed and the testing methodology are described. The main results confirm the basic attributes of the IPC (robust power flow control characteristic, fault current limitation and decoupling of the interconnected networks) and that the IPC can be built from conventional equipment. Random testing performed on the simulator proved to be useful in assessing the maximum stresses on the equipment View full abstract»

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  • Evaluating the availability of electrical substations: a dynamic methodology

    Page(s): 1755 - 1764
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    This paper proposes a technique for evaluating the availability of substations and switching stations including the average cost of repairs of damaged equipment (corrective maintenance), the impact of disturbances on equipment availability and the impact of disturbances on the continuity of the service provided by the substation. The approach is based on the concept of disruptive events, sequence-based processes, state graphs and Markov techniques. The paper illustrates the technique by comparing the availability of two possible substation layouts. The results clearly show the benefit that can be obtained using this objective method of comparison View full abstract»

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Aims & Scope

Installation and operation of apparatus, equipment, structures, materials and systems for the safe, reliable and economic generation, transmission, distribution, conversion, measurement and control of electric energy.

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Meet Our Editors

Editor-in-Chief
Wilsun Xu
Ph.D., P.Eng.
Dept. Electrical and Computer Eng.
University of Alberta
(9107 - 116 Street)
Edmonton, Alberta T6G 2V4 Canada
wxu@ualberta.ca
Phone:780-492-5965
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