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Power Delivery, IEEE Transactions on

Issue 1 • Date Jan. 2002

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Displaying Results 1 - 25 of 39
  • Bibliography of relay literature, 2000 IEEE committee report

    Page(s): 75 - 84
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (66 KB) |  | HTML iconHTML  

    The latest of a series of classified lists of power system relaying references, begun in 1927, is presented. The papers listed include references to the subjects of service restoration, testing, and methods of calculation, as well as to the field of relaying. Each reference includes the title, author, publication information, and a very brief summary of the subject matter. The listing of the titles is subdivided into ten sections, depending upon the general substance of each article. The section titles are as follows: relaying algorithms; distribution and network protection; transmission line protection; relay input sources; rotating machinery protection; other protection; fault and system calculations; maintenance, testing, analysis, and modeling; stability, out of step, restoration; and surge phenomena. This bibliography is in continuation to the bibliographies of relay literature, which were published previously. View full abstract»

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  • Sequential tripping strategy for a transmission network back-up protection expert system

    Page(s): 68 - 74
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (131 KB) |  | HTML iconHTML  

    This paper describes a sequential tripping strategy used in a wide area back-up protection expert system (BPES) to combat situations in which protection relays have maloperated or information is missing. The BPES is an innovative back-up protection scheme designed to prevent the occurrence of widespread blackouts. The BPES evaluates the certainty that transmission lines are likely to be affected by the fault and uses a sequential tripping strategy to isolate the fault if a firm decision is not available due to maloperated relays and/or missing information. The mode of analysis and the sequential tripping strategy ensures that the BPES will clear a fault at minimum risk to the network. An example is included to demonstrate how the certainty factor based sequential tripping strategy is employed by the BPES to clear a fault which occurred on the South Western part of the UK National Grid System View full abstract»

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  • On the economic selection of medium voltage cable sizes in nonsinusoidal conditions

    Page(s): 1 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (159 KB) |  | HTML iconHTML  

    Selection of cable size in the nonsinusoidal conditions is only based on ampacity considerations without any attention to the cost of the losses that will be suffered in the cable life. Since the cost of these losses (fundamental plus harmonics) can assume significant values, the selection of a cross section higher than required for ampacity considerations can result in a large reduction of cost. This paper proposes a method which allows the optimal economic selection of medium-voltage cables in nonsinusoidal operating conditions; it takes into account the initial investment costs and the Joule losses costs, including the additional costs due to current harmonics. It employs simplified expressions similar to those adopted by the IEC Standard in sinusoidal conditions, being the harmonic presence taken into account by a proper definition of a harmonic loss factor and by the introduction of harmonic coefficients to be predicted. Numerical applications to medium-voltage cables are developed and discussed in order to show the sensitivity of the cable optimum size to variations in the coefficients that characterize the harmonic presence View full abstract»

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  • Power disturbance classifier using a rule-based method and wavelet packet-based hidden Markov model

    Page(s): 233 - 241
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (153 KB) |  | HTML iconHTML  

    This paper presents a novel classification method for power distribution line disturbances using a rule-based method and a wavelet packet-based hidden Markov model (HMM). The rule-based method is utilized for the classification of time-characterized-feature disturbances, and the wavelet packet-based HMM is utilized for the frequency-characterized-feature power disturbances. This proposed method classifies six types of actual recorded power distribution disturbances, i.e., sag, interruption, fast capacitor switching, capacitor switching, normal variation, and impulse disturbance, and obtains 98.7% correct classification rate for 670 actual disturbance events tested View full abstract»

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  • An agent-based current differential relay for use with a utility intranet

    Page(s): 47 - 53
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (189 KB)  

    This paper proposes an agent-based current differential relay for use with a communication network. Agents are software processes capable of searching for information in networks, interacting with pieces of equipment and performing tasks on behalf of their owners (relays). Results illustrating the performance of the agent-based differential method proposed acting within a communication structure are presented for different traffic conditions. These results also show that a dedicated utility intranet is a viable and recommended option as a communication media for the proposed scheme View full abstract»

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  • Multisensor secondary device for detection of low-level arcing faults in metal-clad MCC switchgear panel

    Page(s): 129 - 134
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (98 KB)  

    This paper describes the development of a multisensor device, based on four different physical phenomena, for reliable detection of low-level arcing faults in metal-clad switchgear. The proposed device was tested for actual arcing, generated on a low-voltage motor control center panel, feeding a dry type 15 kVA, 230/115 V Y/Δ transformer. Some results showing the performance of the developed device are presented in the paper. The device can also be applied for detection of arcing in power electronic drives, dry type transformers, gas insulated switchgear, generator bus-ducts, and other metal-clad electrical apparatus View full abstract»

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  • A new digital relay for generator protection against asymmetrical faults

    Page(s): 54 - 59
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (121 KB)  

    Under unbalanced conditions three phase instantaneous power oscillates at twice the power system frequency. The magnitude of these oscillations can be used as a measure of the system unbalance. This paper has introduced a new digital relaying algorithm designed to detect asymmetrical faults by monitoring the sinusoidal oscillations of the three-phase instantaneous power measured at the generator terminal. Once an asymmetrical fault is detected, the algorithm checks the direction of the negative sequence-reactive power flow at the machine terminal to discriminate between internal and external faults. Power system test studies presented show that the new relay provides fast tripping for internal asymmetrical faults and back up protection for external asymmetrical fault conditions View full abstract»

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  • A digital simulator for determining the performance limits of computer relays

    Page(s): 60 - 67
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (150 KB) |  | HTML iconHTML  

    Unlike most other digital simulators that generate test waveforms for specific system configurations, playback previously recorded fault waveforms, or randomly generate artificial waveforms, the digital simulator presented in this paper generates the worst case waveforms for specified bounds on noise components present in the relay input signals. As a result, the performance limits of a computer relay can be determined, for specified bounds on its noise components, by performing a single test only. The parameters that define the worst case waveforms; are obtained by utilizing a modified univariate search algorithm. The PC-based simulator was implemented using a general-purpose multifunction card and a graphical programming package called Visual Designer. It did not require any text-based programming for tasks such as interfacing, digital-to-analog conversion, and outputting the discrete analog values of the generated waveform under hardware control. For demonstrating the operation of the digital simulator, a computer relay was also developed in the laboratory and its performance limits were determined View full abstract»

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  • Adaptive non-communication protection for power lines BO scheme. II. The instant operation approach

    Page(s): 92 - 96
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (104 KB) |  | HTML iconHTML  

    This paper presents an instant operation scheme of a adaptive noncommunication protection technique for power lines. In the technique, protection relays make tripping or reclosure decisions adapting to system and fault conditions without the need for communication links. The noncommunication is achieved by the detection of whether or not the system is in a balanced operation, in order to identify the breaker operation at the remote end of the protected section. In the scheme, the distance relay will trip instantly when a fault is detected outside its zone 1, but within its zone 2 reach. Subsequently, it detects whether the fault is on the protected section or not, and recloses when a fault is cleared from the protected line section. Simulation studies with responses to various system and fault condition have shown that the technique is able to give fast and correct response without the need for a communication link View full abstract»

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  • Power losses in steel pipe delivering very large currents

    Page(s): 25 - 32
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (207 KB) |  | HTML iconHTML  

    This paper presents a finite difference time domain solution for the electromagnetic fields in ferromagnetic conducting steel pipes of the type used to deliver large currents for in situ heating of heavy oil reservoirs and for in situ environmental decontamination. A method is described whereby a single measured hysteresis loop can be used to deduce the family of hysteresis loops that governs the variable magnetic behavior throughout the pipe wall. Hysteresis and eddy current losses are calculated, and it is shown that hysteresis effects greatly alter the eddy current distribution and can more than triple the total power losses in the steel pipe when compared to the power losses that would be present if hysteresis effects are ignored and magnetic permeability is assumed constant View full abstract»

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  • Measurement of network harmonic impedances: practical implementation issues and their solutions

    Page(s): 210 - 216
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (119 KB) |  | HTML iconHTML  

    Determination of network harmonic impedances using pre- and post-disturbance steady-state waveforms is a well-known technique. Due to practical constraints, however, it is not quite straightforward to implement the technique for real-life applications. Using an actual utility case as an example, this paper presents practical implementation issues involved and their solutions. Improvements are made to the technique by applying α-β-0 transformation on three-phase measurements. The usefulness of the improved technique is demonstrated with simulation and field measurement results. Since the technique only requires steady-state data, it can be easily implemented with many common power quality meters. One of the applications of the technique is to determine the existence of resonance conditions for shunt capacitor applications View full abstract»

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  • Adaptive non-communication protection for power lines BO scheme 3-The accelerated operation approach

    Page(s): 97 - 104
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (179 KB)  

    This paper presents the accelerated operation scheme of the adaptive noncommunication protection technique for power lines with complex configurations, such as multi-end feeders and ring mains. In the scheme, the overcurrent directional relays are arranged in two operating modes, the fixed time operation and accelerated operation. The relays with faster operating time in the conventional time grading coordination remain unchanged. The new technique is employed to enable accelerated operation to be achieved for the relays which are in the positions for which slow operating time is set when using conventional time grading technique. For a fault occurring on the protected system, the relays of fixed time operation mode will operate at the preset time for the fault within its protected direction. The relays which are programmed to use accelerated operation mode will determine whether a fault is on the protected section or not by using the BO technique, that is to detect the circuit breaker operation by determining whether the line section is in a balanced operation condition or not. The relay makes accelerated tripping decisions for a fault on its protected section. Simulation studies of the responses to various system and fault conditions show that the scheme can significantly increase the speed of the relay responses in the protection of power line systems with complex configurations View full abstract»

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  • Instability of the continuously transposed cable under axial short-circuit forces in transformers

    Page(s): 149 - 154
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (113 KB) |  | HTML iconHTML  

    The axial instability of the winding conductor is one of the principal modes of mechanical failure in large power transformers. It is caused by axial compressive forces generated by the electromagnetic interaction of the short-circuit current and the radial leakage flux. It is a buckling type of mechanical instability that occurs under compression. Two possible modes of failure in the layer type coil wound with the continuously transposed cable are identified and analyzed in this paper. The critical design loads leading to instability of the individual strands as well as of the whole cable are separately derived. The actual instability threshold of the coil would be the lesser of the two critical loads. For the through-fault integrity of the transformer design, this threshold must be greater than the peak compressive force on the cable under the worst case short-circuit current View full abstract»

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  • On-line detection and location of low-level arcing in dry-type transformers

    Page(s): 135 - 141
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (130 KB) |  | HTML iconHTML  

    This paper describes the development of a microprocessor based system, based on four different physical phenomena, for reliable and accurate detection and location of arcing in dry-type transformers. The proposed technique was tested for actual arcing, generated on a 15-kVA, 230/115-V Y/Δ transformer enclosed in a 30" × 30" × 21" metallic enclosure. Some results showing the performance of the detection and location system are presented in the paper. The technique can be applied to detect arcing in metal-clad low-voltage/medium voltage switchgear, drives, gas insulated switchgear (GIS), generator bus-ducts, and other metal-clad electrical apparatus against arcing View full abstract»

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  • Sparse network equivalent based on time-domain fitting

    Page(s): 182 - 189
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (131 KB) |  | HTML iconHTML  

    The paper presents an approach for network equivalent calculation for the analysis of electromagnetic transients in power systems. It is based on time-domain fitting and enforces some degree of sparsity while preserving the accuracy of the equivalent. The calculated equivalent is appropriate for direct interface with the rest of the system in time-domain. A constrained least squares solution of the time-domain fitting equations is used to ensure accuracy at 0 and 60 Hz. Results demonstrating the accuracy and computational efficiency of the method are presented View full abstract»

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  • Time-varying harmonics. II. Harmonic summation and propagation

    Page(s): 279 - 285
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (115 KB)  

    This paper represents the second part of a two-part article reviewing the state of the art of probabilistic aspects of harmonics in electric power systems. It includes tools for calculating probabilities of rectangular and phasor components of individual as well as multiple harmonic sources. A procedure for determining the statistical distribution of voltages resulting from dispersed and random current sources is reviewed. Some applications of statistical representation of harmonics are also discussed View full abstract»

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  • The impact of inrush currents on the mechanical stress of high voltage power transformer coils

    Page(s): 155 - 160
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (137 KB) |  | HTML iconHTML  

    From failure experience on power transformers, it was very often suspected that inrush currents, occurring when energizing unloaded transformers, were reason for damage. In this paper, it was investigated how mechanical forces within the transformer coils build up under inrush compared to those occurring at short circuit. Two-dimensional and three-dimensional computer modeling for a real 268 MVA, 525/17.75 kV three-legged step up transformer was employed. The results show that inrush current peaks of 70% of the rated short circuit current cause local forces in the same order of magnitude as those at short circuit. The resulting force summed up over the high voltage coil is even three times higher. Although inrush currents normally are smaller, the forces can have similar amplitudes as those at short circuit however with longer exposure time. Therefore, care has to be taken to avoid such high inrush currents. Today controlled switching offers an elegant and practical solution View full abstract»

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  • Comparative study of modern heuristic algorithms to service restoration in distribution systems

    Page(s): 173 - 181
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (120 KB) |  | HTML iconHTML  

    This paper presents a comparative study for four modern heuristic algorithms (MHAs) to service restoration in distribution systems: reactive tabu search, tabu search, parallel simulated annealing, and genetic algorithm. Since service restoration is an emergency control in distribution control centers to restore out-of-service areas as soon as possible, it requires fast computation and high quality solutions for customers' satisfaction. The problem can be formulated as a combinatorial optimization problem to divide the out-of-service area to each power source. The effectiveness of the MHAs is compared against each other on typical service restoration problems View full abstract»

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  • Feeder-switch relocation for customer interruption cost minimization

    Page(s): 254 - 259
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (129 KB) |  | HTML iconHTML  

    Most electricity service interruptions are due to failures in the distribution network. In a competitive market, service quality and reliability have become an essential part of the business. In order to enhance the reliability in the distribution system, a value-based method is proposed in this paper to take load distribution changes into account and search for new locations of feeder sectionalizers such that the customer interruption costs (CIC) can be reduced. Two stages are involved in the search. Using local information, the first stage determines the search direction and, in the second stage, it decides whether a crossover of the load point is beneficial. To avoid being trapped in a local minimum, a mutation technique is also applied to look for the global optimum. Actual feeders were used in the tests and test results have shown that with a proper adjustment of the feeder sectionalizers, service reliability can be improved and the customer outage costs are reduced View full abstract»

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  • Reliability cost/worth assessment of distribution systems incorporating time-varying weather conditions and restoration resources

    Page(s): 260 - 265
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (131 KB) |  | HTML iconHTML  

    This paper presents a time-sequential simulation technique incorporating the effects of weather conditions and restoration resources in reliability cost/worth evaluation of distribution systems. Time-varying weight factors (TVWF) are introduced to represent the effects on component failure rates and restoration times of weather and available restoration resources. The average failure rate is combined with the TVWF to create time-varying failure rates (TVFRs) for each component. The average restoration time is combined with the TVWF to create time-varying restoration times (TVRTs). Studies conducted in a test distribution system show that the TVFR have large impacts on the interruption costs of frequency-sensitive customers and slight effects on others. The TVRT have significant effects on the indices for all the customers. It is therefore important to consider TVRT in evaluating reliability cost/worth of network reinforcement View full abstract»

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  • A new PMU-based fault location algorithm for series compensated lines

    Page(s): 33 - 46
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (356 KB) |  | HTML iconHTML  

    This paper presents a new fault location algorithm based on phasor measurement units (PMUs) for series compensated lines. Traditionally, the voltage drop of a series device is computed by the device model in the fault locator of series compensated lines, but when using this approach errors are induced by the inaccuracy of the series device model or the uncertainty operation mode of the series device. The proposed algorithm does not utilize the series device model and knowledge of the operation mode of the series device to compute the voltage drop during the fault period. Instead, the proposed algorithm uses two-step algorithm, prelocation step and correction step, to calculate the voltage drop and fault location. The proposed technique can be easily applied to any series FACTS compensated line. EMTP generated data using a 30-km 34-kV transmission line has been used to test the accuracy of the proposed algorithm. The tested cases include various fault types, fault locations, fault resistances, fault inception angles, etc. The study also considers the effect of various operation modes of the compensated device during the fault period. Simulation results indicate that the proposed algorithm can achieve up to 99.95% accuracy for most tested cases View full abstract»

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  • An improvement for the selection of surge arresters based on the evaluation of the failure probability

    Page(s): 123 - 128
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (120 KB) |  | HTML iconHTML  

    An improvement on the typical selection procedure of arresters is presented. The analysis shows that the risk of failure of an arrester depends on several parameters (the striking point, the lightning current waveform, the arrester itself and the system configuration). Therefore, the selection of the optimal arrester depends on how well its stresses can be estimated. After the application of the typical selection procedure, the power system simulations are carried out using the Electromagnetic Transients Program (EMTP) for each suitable arrester. From these results the failure probability of each arrester is calculated, which permits the optimal selection from several valid arresters by the comparison of their risk of failure View full abstract»

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  • Exact modeling of the voltage source converter

    Page(s): 217 - 222
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (115 KB)  

    A discrete time, linear time varying model of the three-phase voltage source converter (VSC) is developed. The model is employed to determine the steady-state operating characteristics of a VSC taking all AC-DC side harmonic interactions into account. The procedure is based on an exact closed form solution of the system equations and does not rely on iterative techniques. The steady-state operating curves from the proposed model are compared with those derived from a conventional continuous time dq-frame model. The accuracy of the conventional continuous time model is shown to be highly dependent on the converter's duty cycle View full abstract»

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  • Phase-to-ground and phase-to-phase sparkover characteristics of external insulation at the entrance of a UHV substation

    Page(s): 223 - 232
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (243 KB)  

    For rational insulation design of a UHV substation, full-scale switching impulse tests of phase-to-ground (shielding ring-to-tower) and phase-to-phase (shielding ring-to-shielding ring) insulating clearance have been carried out in dry and wet conditions. In the tests, shielding rings that will be installed on bushings at actual UHV substations were used. The sparkover voltages depend on not only gap configurations but also the waveform of applied switching impulses; in other words, they show what we refer to as U-characteristics. Critical sparkover voltages are higher than those of rod-rod gaps by 20%-25% in dry conditions and by 7%-10% in wet conditions View full abstract»

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  • An adaptive scheme for parallel-line distance protection

    Page(s): 105 - 110
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (115 KB) |  | HTML iconHTML  

    This paper describes an adaptive protective relaying scheme for parallel-line distance protection. The scheme adjusts its operation based on the availability of input signals to achieve an optimal distance protection performance on parallel transmission lines influenced by the mutual coupling effect. When available, zero sequence current from the parallel line is used to fully compensate the mutual coupling effect. The zero sequence current ratio is used to avoid possible false operations on healthy lines, which may result from such compensation. When the parallel line's zero sequence current is not available, the line operating status is used instead to select the proper zero sequence current compensation factors in impedance calculation. Default zero sequence current compensation factor is used when both the parallel line's zero sequence current and line operating status signals are not available. The performance of the scheme has been verified on a simulated network and the results are presented 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
Fax:780-492-1811