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Power Delivery, IEEE Transactions on

Issue 2 • Date April 1997

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Displaying Results 1 - 25 of 75
  • Bibliography of relay literature, 1995. IEEE Committee Report

    Page(s): 650 - 659
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    The latest of a series of classified lists of power system relaying references, begun in 1927, is presented. This bibliography is in continuation to the bibliographies of relay literature which were published previously. View full abstract»

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  • Modeling synchronous voltage source converters in transmission system planning studies

    Page(s): 947 - 952
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    A voltage source converter (VSC) can be beneficial to power utilities in many ways. To evaluate the VSC performance in potential applications, the device has to be represented appropriately in planning studies. This paper addresses VSC modeling for EMTP, power flow and transient stability studies. First, the VSC operating principles are overviewed and the device model for EMTP studies is presented. The ratings of VSC components are discussed, and the device operating characteristics are derived based on these ratings. A power flow model is presented and various control modes are proposed. A detailed stability model is developed, and its step-by-step initialization procedure is described. A simplified stability model is also derived under stated assumptions. Finally, validation studies are performed to demonstrate performance of developed stability models and to compare it with EMTP simulations View full abstract»

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  • Capacitor placement and real time control in large-scale unbalanced distribution systems: loss reduction formula, problem formulation, solution methodology and mathematical justification

    Page(s): 953 - 958
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (656 KB)  

    A comprehensive study of capacitor placement and real-time control in general unbalanced distribution systems is undertaken. New developments in a loss reduction formula, problem formulations, solution methodology and mathematical justification are presented. The problem is decoupled into two subproblems: the capacitor placement subproblem; and the real-time control subproblem. An effective solution algorithm for placing capacitors and determining their real-time control schemes for general unbalanced distribution systems is proposed. To meet the need for efficient implementation in real-time environments, a fast pseudo gradient-type mechanism for deriving capacitor control settings is incorporated into the solution algorithms. A quadratic integer programming based approach is proposed to determine the number, locations and sizing of capacitors to be placed in the distribution systems. The subproblem of determining capacitor control settings under varying loading conditions is formulated as another quadratic integer programming problem. Mathematical justification is provided to show that the proposed algorithms are guaranteed to yield local optimal solutions View full abstract»

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  • Evaluation of pulling rope wear and coefficient of friction for pipe-type cables

    Page(s): 542 - 546
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    The coefficient of friction between the pulling rope and cable pipe for a high-pressure fluid-filled cable was determined in order to characterize the effects of pulling tension and sidewall pressure on this parameter. Pipe wear was also measured. The study found that variations in pulling tension were more strongly affected by pulling rope wear than pipe wear. The coefficient of friction of the pulling rope varied from 0.27 to 0.75. Pipe wear of 1.52 mm (60 mils) was measured during 430 m (1425 ft.) of pulls at 1414 kgf/m (950 lbs./ft.) sidewall pressure and 1.02 mm (40 mils) of wear was measured during 290 m (950 ft.) of pulls at 610 kgf/m (410 lbs./ft.) sidewall pressure View full abstract»

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  • Capacitor placement and real time control in large-scale unbalanced distribution systems: numerical studies

    Page(s): 959 - 964
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (580 KB)  

    A novel solution algorithm for capacitor placement and real-time control in real large-scale unbalanced distribution systems is evaluated and implemented to determine the number, location, size, type and control schemes of capacitors to be placed on large-scale unbalanced distribution systems. A detailed numerical study regarding the solution algorithm in large scale unbalanced distribution systems is undertaken. Promising numerical results on both 292 bus and 394 bus real unbalanced distribution systems containing unbalanced loads and phasing and various types of transformers are presented. The computational performance for the capacitor control problem under load variations is encouraging View full abstract»

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  • Design and application of aerial systems using insulated and covered wire and cable

    Page(s): 1006 - 1011
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    Insulated and covered wires and cables have been used in aerial power conductor applications for over fifty years. Despite this long history, the design, application and operation of these different types of conductor constructions are frequently misunderstood and confused with one another. Electric utilities have increasing needs for greater reliability and higher quality of service, growing concerns over electromagnetic fields, increased difficulty in obtaining right-of-way and tree trimming, and difficulty in maintaining clearances in congested areas. These challenges have resulted in expanded interest in using covered or insulated cables in aerial systems. This paper: (a) describes the differences between the constructions; (b) answers questions, concerns and misconceptions about these aerial designs; and (c) ranks the performance of each relative to desired attributes. A logical system for classifying covered wire and cable is also proposed View full abstract»

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  • Automation of the ANSI C119.4-1991 connector test

    Page(s): 560 - 564
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    Automation of the ANSI C119.4-1991 connector test has been expensive. The ANSI test requires accelerated aging using AC current. The resistance of each connector must be measured periodically using DC current. These requirements generate the need for two power sources switched in and out by a computer-controlled relay. This relay must have contact current carrying capabilities equal to that of the cable on test. For large conductor sizes this expense becomes formidable. A method of making accurate ohm measurements of the connectors without connecting or disconnecting the conductor is given in this paper. Automation of the test can be established for a minimal investment with the information given. Automation will allow more information to be gathered, which will lead to the connector aging process being better understood and controlled View full abstract»

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  • Substation based data interpretation techniques for improved power system management

    Page(s): 700 - 706
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    There is now considerable pressure on electric utilities to operate their power systems in the most efficient manner possible and to provide increased quality of service to customers. This pressure, coupled with the decreasing availability of reserve margins, dictates that there is a requirement for comprehensive power system operation support through, among other things, the provision of quality information relating to the behaviour of the primary and secondary systems. This paper shows how the data available within modern substation control and management systems can be exploited in a cost-effective manner, through the implementation of advanced substation functions in an open systems environment. Certain functions which are presently carried out at the control centre could be distributed (or partially distributed) to the substation. These functions may provide utility staff with quality information, which can in turn be used to satisfy the objectives of increasing quality and security of supply, in addition to optimising the utility's information, maintenance and asset management functions View full abstract»

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  • Outdoor polymeric insulators long-term exposed to HVDC

    Page(s): 1041 - 1048
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    Field experience from outdoor polymeric insulators exposed to HVDC under natural contamination conditions is presented. This paper summarizes the peak leakage current statistics, the hydrophobicity and the surface material conditions studied by electron spectroscopy for chemical analysis (ESCA) and attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. The results show a strong interrelation between the surface conditions and the performance with respect to leakage currents. Moreover, the results show that the surface conditions and the performance of the insulators exposed to HVDC are rather similar to those of the insulators exposed to HVAC View full abstract»

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  • Application of current limiting fuses in distribution systems for improved power quality and protection

    Page(s): 791 - 800
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    This paper presents a comparative analysis of the effects of distribution system expulsion and current limiting fuse operations on power quality. To perform this analysis, digital fuse models were developed for use with the EMTP/ATP program. Expulsion fuses interrupt current at current zeros and are easily modeled. Current limiting fuses (CLFs) interrupt current by forcing a current zero and therefore, require a special modeling technique. CLFs were modeled by representing them as nonlinear resistances. The nonlinear resistances were calculated using laboratory test results of actual CLF operations. This technique is very convenient for simulating CLF operations and analyzing their interaction with the distribution system. This paper shows that CLFs improve power quality by supporting system voltage during faults and reducing voltage dip duration. Additionally, CLFs reduce the fault let-through I2t View full abstract»

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  • Modelling of single-phase nonuniform transmission lines in electromagnetic transient simulations

    Page(s): 916 - 921
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    An exponential single-phase line model is introduced to represent nonuniform transmission lines. When the line parameters are assumed to vary exponentially, a set of two-port equations can be formed in the frequency domain, which contain frequency-dependent functions. These functions are then synthesized with rational functions of the minimum-phase-shift type. Utilizing a fast recursive convolution technique, the time-domain equations of the proposed model reduce to a form similar to those in Bergeron's method. Plus, the model is compatible with general electromagnetic transients programs such as the EMTP. Time-domain simulations with the proposed model show good agreement with published experimental results, and with those produced by a cascade multi-section model where the line is divided into many short sections of uniform transmission lines View full abstract»

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  • Safety considerations of aerial systems using insulated and covered wire and cable

    Page(s): 1012 - 1016
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (712 KB)  

    Insulated and covered wires and cables have been used in aerial power conductor applications for over fifty years. Some have suggested that covered wires and cables should be used in general applications solely for the purpose of providing safety to operating personnel and the general public. This paper discusses factors leading to the conclusion that nonshielded, covered conductors should not be installed solely to assure personal safety. The National Electrical Safety Code (NESC) treats covered conductors as bare conductors for purposes of clearances to personnel spaces; such a requirement is strongly supported by this paper View full abstract»

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  • Risk assessment basis of moving particles in gas insulated substations

    Page(s): 714 - 721
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    Comprehensive acoustic measurements on bouncing particles in a gas insulated substation (GIS) have been carried out. The objective is to find parameters that both are available from external acoustic measurements and usable for assessing whether a particle has the potential to cause an insulation breakdown. The elapsed time between subsequent particle impacts is a measure of how far into the high-field region the particle can move, and thus also a measure on criticality. Secondly, the amplitude of the acoustic signal generated as a particle imparts the enclosure increases with increasing particle length and thus also with increasing criticality. Moreover, plotting these two parameters against each other (`particle flight time' vs. `signal amplitude at impact') for a significant number of impacts (e.g. 1000) always yields a very characteristic pattern, which in itself is a strong indication that the recorded signals are generated by one moving particle View full abstract»

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  • A distributed on-line HV transmission condition monitoring information system

    Page(s): 707 - 713
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    China Light and Power Company Ltd. (CLP) is responsible for supplying electricity to the whole of Hong Kong except Hong Kong Island and Lamma Island. In CLP's Castle Peak power plant, 18 kV and 23 kV electric supplies are generated. The voltage is then stepped up to 400 kV for transmission. The intermediate control between those transformers and the major 400 kV overhead transmission system lies with a standard “one and a half breaker configuration” switching substation. The substation houses single phase encapsulated SF6 circuit breakers. In the urban centres, 400 kV substations are installed to step down 400 kV to 132 kV or further to 11 kV for distribution. This paper describes the development of an online distributed information system for monitoring the condition of the whole HV transmission system. The system continuously monitors the status of each circuit breaker (CB) together with important operational parameters, such as duration during making and breaking, operations of hydraulic pumps and SF6 gas pressure etc. Each group of CBs is monitored by a stand-alone microcontroller which is interconnected with all other microcontrollers using a local area network with a baud rate of 9,600. The information can be recorded on the hard disk of an onsite microcomputer and further transmitted back to a remote computer for alarm generation and multi-station supervision. The CLP 400 kV substation and the Tsz Wan Shan 400 kV substation are amongst the first targets for development View full abstract»

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  • Reliability centered maintenance for transmission systems

    Page(s): 1023 - 1028
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    The regulatory and market forces that are challenging the electric utility industry require more proactive methods of utility asset management. An important component of asset management for electric utilities is the maintenance of existing power transmission lines. Therefore, some utilities are working to implement a condition-based, predictive transmission line maintenance program using the concepts of reliability centered maintenance View full abstract»

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  • An implementation of a hybrid intelligent tool for distribution system fault diagnosis

    Page(s): 1035 - 1040
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    The common fault in distribution systems due to line outages consists of single-line-to-ground (SLG) faults, with low or high fault impedance. The presence of arcing is commonplace in high impedance SLG faults. Recently, artificial intelligence (AI) based techniques have been introduced for low/high impedance fault diagnosis in ungrounded distribution systems and high-impedance fault diagnosis in grounded distribution systems. So far no tool has been developed to identify, locate and classify faults on grounded and ungrounded systems. This paper describes an integrated package for fault diagnosis in either grounded or ungrounded distribution systems. It utilizes rule-based schemes as well as artificial neural networks (ANN) to detect, classify and locate faults. Its application on sample test data as well as field test data are reported in the paper View full abstract»

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  • Modeling of altitude effects on AC flashover of polluted high voltage insulators

    Page(s): 810 - 822
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    The paper introduces a new physical approach to account for the effect of reduced air density on the flashover voltage and critical leakage current of polluted high voltage insulators. The analysis starts by updating the mathematical model, previously established, of power frequency flashover of polluted insulators at normal atmospheric pressure. It then proceeds to introduce the effect of ambient pressure on the physical parameters of the dielectric recovery equation. The effect of reduced pressure on the arc boundary radius is investigated. The combined effect of humidity and reduced air density on the dielectric strength at ambient temperature is also accounted for. The above analysis results in a new expression for the reignition voltage which includes ambient pressure effects. The analytical findings are then used to investigate the effect of reduced air density on the critical leakage current and flashover voltage of simple-shaped polluted insulators. The effect of more complex profiles is subsequently introduced. The model results are compared with experiments and the agreement established is quite satisfactory. Finally simple practical altitude correction factors for polluted insulators are proposed View full abstract»

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  • Corrosion in HVDC valve cooling systems

    Page(s): 1049 - 1052
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    Stainless steel couplings in the main cooling water pipes of HVDC thyristor valves have been in use since 1983, with overall satisfactory behavior. However, some water leakage due to corrosion below the sealing O-rings of the couplings was observed during 1992. An extensive investigation and follow-up worldwide showed a direct correlation between water quality and the corrosion rate of these stainless steel couplings. Recommendations are given as to actions to be taken in order to maintain a long lifetime for the fine water systems View full abstract»

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  • Usage of CLPU curve to deal with the cold load pickup problem

    Page(s): 660 - 667
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    Restoration of load after an extended power outage, whether planned or unplanned, raises various practical concerns. Previous studies have shown the cold load condition lasts between 2 to 60 minutes, or longer, depending on the duration of the outage, type of load and the local weather. The theory presented in this paper is applicable to all microprocessor-based overcurrent protective devices used at the distribution level. The example used in the paper is to provide a possible method to handle cold load pickup problems at line reclosers installed on the distribution system. The new approach is to control the pickup of the phase element of the recloser as a function of time. The pickup of the recloser starts at a preset value after an extended outage and slowly decreases and returns to the normal pickup in a predetermined manner. The relationship of the pickup level and time could be determined by considering the maximum cold load current and its gradual decay with time View full abstract»

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  • Controlled closing on shunt reactor compensated transmission lines. II. Application of closing control device for high-speed autoreclosing on BC Hydro 500 kV transmission line

    Page(s): 741 - 746
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    In the past, BC Hydro used circuit breaker closing resistors to limit switching surges on its 500 kV transmission system. This approach was considered undesirable for new transmission lines and an innovative scheme incorporating special transmission line surge arresters and controlled high-speed autoreclosing of the circuit breaker was developed. The scheme and its basis as applied on a new 330 km long 500 kV transmission line are described. Actual line switching tests, also described, confirmed the validity of the studies performed and applied design concepts, and the value of the scheme View full abstract»

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  • Long term magnetic field monitoring near power lines

    Page(s): 922 - 927
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    As part of regulatory requirements, a US electric utility is carrying out a long-term magnetic field monitoring program before and after a substation expansion. The program began with the drafting of a strict protocol to ensure that data collection over time by different personnel will follow exactly the same procedures. As other utilities may be involved in similar regulatory processes, this paper presents a long-term monitoring protocol, and the results of about 91 site-months of data from six monitoring sites before energization of the new facilities. Operating experience shows that the protocol was well conceived and can be executed with little supervision. Measurement results show daily, weekly and seasonal cycles of magnetic field levels near power lines. Normalized percentiles and means show that these cycles were similar at all six sites, and there was an upper bound for field levels at each site. Throughout the monitoring period, which exceeded 18 months at some sites, maximum magnetic field levels with durations longer than 15 minutes were about 270% or less of the medians View full abstract»

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  • Examination of ELCOM-90, TASE.1, and ICCP/TASE.2 for inter-control center communication

    Page(s): 607 - 615
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    The electric power community is striving to achieve uniform and standardized inter-control center communication. Such communication would make it possible to interact and exchange data more easily between control centers, reduce communication related costs and simplify the integration of new equipment and applications. Two major concepts are present in the field: ELCOM; and ICCP. These concepts together with their proposed standards, TASE.1 and TASE.2, are examined in this paper. The treatment is focused on the protocol profiles and the functionality and operation of the concepts. Also, issues related to migration and acceptance are dealt with. Knowledge of the pros and cons of these issues should support and guide a potential user in choosing an inter-control center communication concept View full abstract»

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  • Performance assessment of an integrated distribution SCADA-AM/FM system

    Page(s): 971 - 978
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    Many potential benefits related to the integrations of various corporate information systems in a utility have been recognized. In order to evaluate an integrated distribution system SCADA and AM/FM system, in this paper, a discrete time simulation method is used. Distributed architectures of SCADA and AM/FM systems and their integration are simulated by using an off-the-shelf simulation package. The changes in the response times of SCADA functions due to the integration are investigated. Test results have indicated that a simple SCADA-AM/FM integration using a data file transfer scheme could enhance distribution system dispatchers' performance in day-to-day work without giving up much in the response times of SCADA functions View full abstract»

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  • Calculation of voltage profiles along transmission lines

    Page(s): 993 - 998
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    A method for calculating transient voltages and currents at a large number of intermediate points along a transmission line is presented. In the family of EMTP-type programs, these “profile” calculations are normally made by explicitly connecting a number of short line sections to create intermediate nodes where voltages and currents can be monitored. This approach is time-consuming, computationally intensive and can be inaccurate if the number of intermediate nodes is large. The model presented here allows the accurate evaluation of voltages and currents at an arbitrary number of equally-spaced points along the line. The frequency dependence of the line parameters is taken into account. It is computationally fast and easy to use View full abstract»

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  • High voltage VLF testing of power cables

    Page(s): 565 - 570
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    This publication describes a laboratory test program conducted with the objective to develop a test that would replace the existing DC withstand test. The article describes the methodology used to establish the voltage duration and magnitude of VLF (0.1 Hz) high voltage field tests suitable for crosslinked polyethylene (XLPE) insulated power cable. The results show that the voltage breakdown of laboratory aged XLPE cable at 0.1 Hz is approximately equal to that at 60 Hz, that proof tests at 0.1 Hz cause very little damage to the cable, and that 0.1 Hz testing appears to be a satisfactory alternate to DC testing. Preliminary values are suggested for voltage magnitude and time duration of cable acceptance, maintenance and proof tests at 0.1 Hz for XLPE cable rated up to 35 kV. A program is underway to similarly evaluate samples of service-aged XLPE cable; as well as to demonstrate the use of the preliminary test values at typical utility installations 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.

Full Aims & Scope

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
Fax:780-492-1811