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Power Delivery, IEEE Transactions on

Issue 1 • Date Jan. 2005

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Displaying Results 1 - 25 of 88
  • Table of contents

    Publication Year: 2005 , Page(s): c1 - 3
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    Freely Available from IEEE
  • IEEE Transactions on Power Delivery publication information

    Publication Year: 2005 , Page(s): c2
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    Freely Available from IEEE
  • Long-term testing and applications of high-stress MV EPR cables

    Publication Year: 2005 , Page(s): 4 - 10
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    High-stress design 35-kV ethylene propylene rubber (EPR)-insulated cables with 1.14-mm (45-mil) wall reduction have been in service for more than ten years. In the mid 1990s, an extensive cable testing program was initiated to demonstrate that high-stress designs up to 4 kV/mm (101.6 V/mil) exhibit a significant electrical and mechanical safety margin to operate on typical utility network systems. Investigations were also undertaken to demonstrate the suitability of accessories for high-stress designs. This paper will present the results of six-year, long-term wet electrical testing conducted to demonstrate that with proper design, the aging performance of standard wall and high-stress design cables provide satisfactory results and suitable performance for the intended application. Additionally, utility field experience is presented on 35- and 15-kV cables operating at high stress. The experience for these 15-kV medium-voltage EPR cable designs employ the highest recommended stress for cables of this class, as well as taking into account the complete system performance. View full abstract»

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  • Novel method of error current compensation for Hall-effect-based high-accuracy current transformer

    Publication Year: 2005 , Page(s): 11 - 14
    Cited by:  Papers (1)
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    A novel scheme for error current compensation of current transformers (CTs) is presented. The method is to apply Hall current transducers (HCTs) based on magnetic force balance to detect and compensate the error current so as to eliminate the error of CT caused by its exciting current. Theoretical analysis and experimental tests clearly illustrate the performance of the proposed scheme. After compensation, the accuracy of the common CT is increased 500 times from 0.5% (5000 ppm) to 0.001% (10 ppm) at the condition of burden Z/sub b/=1 /spl Omega/, cos /spl phi/=1. A self-calibrating method is adopted for a current transformer with the wind ratio of 1:1. View full abstract»

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  • An impulse voltage calibrator of low output impedance

    Publication Year: 2005 , Page(s): 15 - 22
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1362 KB)  

    A calibrator that produces full lightning impulses and chopped lightning impulses with variable chopping time is described. The calibrator uses series-connected power metal-oxide field-effect transistors as the main impulse switch and insulated gate bipolar transistors (IGBTs) as the chopping switch, and its output impedance is low to drive a termination impedance of 50 /spl Omega/. The performance of the calibrator is verified by comparing the simulated calibrator output parameters based on the calibrator component values and output parameters calculated from measured output waveforms using a calibrated digitizer. View full abstract»

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  • Measurement of harmonics/inter-harmonics of time-varying frequencies

    Publication Year: 2005 , Page(s): 23 - 31
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    A novel method of extraction and measurement of individual harmonics of a signal with time-varying frequency is presented. The proposed method is based on a nonlinear, adaptive mechanism. Compared with the well-established techniques such as DFT, the proposed method offers (i) higher degree of accuracy, (ii) structural/performance robustness, and (iii) frequency-adaptivity. The structural simplicity of the algorithm renders it suitable for both software and hardware implementations. The limitation of the proposed method as compared with DFT-based methods is its slower transient response. Based on simulation studies, performance of the method is presented and its accuracy and response time are compared with a DFT-based method. View full abstract»

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  • A new hybrid current sensor for high-voltage applications

    Publication Year: 2005 , Page(s): 32 - 38
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    This article presents a new hybrid electro-optic/inductive current sensor for metering and protective relaying applications. The sensor combines a Rogowski coil with a passive integrator located in the high-voltage environment. An integrated-optic Pockels cell (IOPC) having integrated electrodes provides optical isolation. Test results from 30 A to 30 kA show the sensor to be highly linear, exceeding 0.2% linearity standards. Temperature cycling tests show the ratio error to have a maximum value of 0.3% over the -30 to +70/spl deg/C range. View full abstract»

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  • An enhanced zone 3 algorithm of a distance relay using transient components and state diagram

    Publication Year: 2005 , Page(s): 39 - 46
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (449 KB)  

    Zone 3 of a distance relay is used to provide the remote backup protection in case of the failure of the primary protection. However, the risk of maloperation under stressed conditions such as heavy loading, voltage, and transient instability is quite high. Zone 3 is used in combination with the derivatives of the voltage and current, etc. to prevent maloperation. At times, the impedance characteristics that restrict the tripping area of relay are used to avoid maloperation due to load encroachment. This work presents a novel zone 3 scheme based on combining the steady-state components (i.e., 60 Hz) and the transient components (TCs) using a state diagram that visualizes the sequence of studies that emanate from the sequence of events. The simulation results show that the novel zone 3 distance relay elements using the proposed method operate correctly for the various events. View full abstract»

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  • Protection issues during system restoration

    Publication Year: 2005 , Page(s): 47 - 56
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (555 KB) |  | HTML iconHTML  

    Power system blackouts are a very rare phenomenon in a well-planned interconnected power system. Nevertheless it is very important to have plans and systems in place to handle any eventuality even if it is remote. This report brings out various issues related to protection during a system restoration process. Power system protection is critical to a safe, efficient, and reliable power system. Protection engineers take every possible care to ensure that protection systems are designed considering all predictable eventualities and these constraints have grown over time. However, during system restoration, after a major blackout, it is possible for the protection elements to be presented with situations, which they can mistake for an unhealthy power system and the protection elements may operate. The prime concern during a power system blackout is to bring the system back to normalcy as fast as possible. At times, if proper care is not taken, the protection system can hinder and delay the restoration of the power system. This report discusses various such conditions that can occur during the blackstart of a power system and also suggests solutions to manage them without compromising the objectives of protection system i.e., to ensure a safe, efficient, and reliable power system. View full abstract»

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  • A practical method for assessing the effectiveness of vector surge relays for distributed generation applications

    Publication Year: 2005 , Page(s): 57 - 63
    Cited by:  Papers (40)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (236 KB)  

    This work presents a simple and reliable method for predicting the islanding detection performance of vector surge relays. The relay performance is characterized by a tripping-time versus power-imbalance curve. With the curve, one can determine the time taken by a vector surge relay to detect islanding for any generation-load mismatch level. The main contribution of this paper is the development of analytical formulas for directly determining the behavior of vector surge relays. As a result, efforts needed to asses the relay performance for a given distributed generation scheme can be simplified significantly. The accuracy of the formulas has been verified by extensive simulation study results. View full abstract»

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  • Design of a bidirectional impedance-adapting transformer coupling circuit for low-voltage power-line communications

    Publication Year: 2005 , Page(s): 64 - 70
    Cited by:  Papers (1)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1050 KB)  

    In this paper, the design of an impedance-adapting bidirectional transformer coupling circuit for low-voltage power-line communications is described. It is shown that transmission through the transformer is governed by series resonance of the leakage inductance and coupling capacitance. At low frequencies though, the magnetizing inductance plays an important role in filtering the power waveform. The coupling transformer, if properly designed, can equalize terminating impedances on either side for maximum power transfer. Furthermore, these equalized terminating impedances facilitate symmetrical bidirectional band-pass transmission. View full abstract»

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  • Computation of high-frequency and time characteristics of corona noise on HV power line

    Publication Year: 2005 , Page(s): 71 - 79
    Cited by:  Papers (1)
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    This work presents an algorithm for the computation of frequency and time characteristics of the corona noise in power-line carrier communications. In the frequency domain, the corona noise is represented with a power spectral density and with a Gaussian noise voltage with variable root mean square value in the time domain. Simulations results are compared with measurements on an actual 400-kV power line. View full abstract»

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  • An analog spread-spectrum interface for power-line data communication in home networking

    Publication Year: 2005 , Page(s): 80 - 89
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (771 KB) |  | HTML iconHTML  

    Communication using power line as a medium of signal transmission offers a convenient and inexpensive solution for multimedia signal transmission and control applications in smart home networking. This work presents a novel analog spread-spectrum (SS) scheme for physical-layer interface in home networking. The proposed communication scheme uses a chaotic system to modulate the information signal for wideband transmission. The wideband spectral property of the transmitted chaotic signal adds robustness to the proposed scheme against the hostile power-line environment that is characterized by non-Gaussian noise and multipath propagation. By exploiting the ergodic property of chaotic signals, a simple noncoherent receiver is developed here. Not only does the proposed analog scheme demonstrate satisfactory communication performance, but it can also be implemented with simple hardware and low manufacturing cost, which is an important consideration for cost-effective home networking. The proposed noncoherent SS system does not involve quantization and complex synchronization process and, hence, it is more efficient in transmitting analog multimedia signals compared to the conventional SS system. Performance analyses illustrate the superior communication performance of the proposed analog SS system over the conventional SS scheme for multimedia signal transmission in a power-line home networking environment. View full abstract»

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  • Multipath characterization of indoor power-line networks

    Publication Year: 2005 , Page(s): 90 - 99
    Cited by:  Papers (73)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (472 KB) |  | HTML iconHTML  

    The time- and frequency-varying behavior of an indoor power-line network is the result of variable impedance loads connected to its termination points. In fact, any signal transmitted through such a communications network is subject to time-varying multipath fading. In this paper, an analytical calculation method is presented, which can be used to determine the multipath components of any point-to-point channel in the indoor power-line environment. The method calculates all transmission characteristics of the network and, therefore, it can be exploited in the process of designing proper transmission algorithms for optimizing system performance. The proposed method is applied to an example network to demonstrate its usefulness in explaining the network's time-dependent behavior and in estimating channel parameters, such as subchannel bandwidth, multipath delay spread, fading conditions, etc. View full abstract»

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  • Estimation of multilayer soil parameters using genetic algorithms

    Publication Year: 2005 , Page(s): 100 - 106
    Cited by:  Papers (23)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (480 KB) |  | HTML iconHTML  

    A methodology has been proposed according to which, after carrying out a set of soil's resistivity measurements, one can compute the parameters of the multilayer earth structure using a genetic algorithm (GA). The results provided by the GA constitute the indispensable data that can be used in circuital or field simulations of grounding systems. The methodology, developed on the base of the PC Opera software package, allows to proceed toward a very efficient simulation of the grounding system and an accurate calculation of potential on the ground's surface. View full abstract»

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  • Optimal design of grounding system considering the influence of seasonal frozen soil layer

    Publication Year: 2005 , Page(s): 107 - 115
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB) |  | HTML iconHTML  

    Frozen soil leads to the change of the soil model. This would affect the safety of the grounding system. The design of the grounding system considering the seasonal frozen soil should be based on the full investigation of the actual maximum depth of the frozen soil and the actual layered soil models. The final design scheme of the grounding system should be determined synthetically from two phases-first, the grounding system is designed in the normal soil model and its safety is checked in the frozen soil model, second, it is designed in the frozen soil model and its safety is checked in the normal soil model. The influences of the frozen soils on the optimal design of grounding systems in homogeneous and double-layer soil models were systematically analyzed, and the respective design methodologies of the grounding systems were proposed. The influence of vertical electrodes on the design of the grounding system considering the seasonal frozen soil was discussed. The analyzed results state that the safety of grounding system can be sufficiently improved by vertical grounding electrodes added to the horizontal grounding grid. View full abstract»

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  • Estimation of the surge arrester outage rate caused by lightning overvoltages

    Publication Year: 2005 , Page(s): 116 - 122
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (248 KB) |  | HTML iconHTML  

    The computation based on the lightning limiting parameters method of the surge arrester minimum energy absorption capability is presented. The sensitivity analyses of certain lightning parameters like lightning current-wave duration and equivalent circuit parameters are performed. The influence of the tower footing impedance to the surge arrester failure rate due to the exceeding energy absorption capability is investigated. The method of selection of the medium voltage surge arrester energy absorption capability based on the allowed failure rate is proposed. View full abstract»

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  • Evaluation of the effective protection distance of low-voltage SPD to equipment

    Publication Year: 2005 , Page(s): 123 - 130
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (424 KB) |  | HTML iconHTML  

    Installing surge protection devices for a low-voltage power supply is important to ensure the survival of electric or electronic devices and systems. Sometimes one group of surge protective devices (SPDs) installed on the distribution board is expected to protect all equipment supplied power by this distribution board. This equipment is connected to the distribution board by cables with different lengths, the influence of the cable length between the SPD and protected equipment on protective effects of SPD was discussed. The reflection and oscillation phenomena of the transient voltage caused by the connecting cables were analyzed, which would affect the protective effects of SPDs. These phenomena depend on the characteristics of the SPDs, the properties of the protected loads, and the length of the connecting cable. Five different types of loads and three different cable lengths have been simulated by electromagnetic transient analysis software, and their respective transient voltages across the SPD and the load were discussed in detail. The effective protection distances of SPD to equipment were analyzed for different types of loads. View full abstract»

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  • Electrical parameter statistic analysis and parallel coordination of ZnO varistors in low-voltage protection devices

    Publication Year: 2005 , Page(s): 131 - 137
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB) |  | HTML iconHTML  

    Analyzing the nonuniformity of electrical parameters of ZnO varistors is useful to select and coordinate the ZnO varistors in parallel operation and improve the protection capability of surge-protection device (SPD). The nonuniformity of 1-mA dc voltage and impulse residual voltage of commercial low-voltage ZnO varistors were estimated by statistic analysis in this paper. The Minimum Gobble Distribution was used to describe the distribution of 1-mA dc voltage and impulse residual voltage, ZnO varistors were verified conforming to the Minimum Gobble Distribution by the Kolmogorov-Smirnov test. The relationship between the impulse residual voltage and 1-mA dc voltage has a chaos phenomenon, and they have a close relative degree by t-test, the impulse residual voltage can be estimated by voltage ratio and 1-mA dc voltage. The nonuniform phenomena of electrical parameters of ZnO varistors were simulated by Voronoi network. The current overload of ZnO varistor with reduced residual voltage is serious, in order to keep safe operation of SPDs, when we design a SPD with ZnO varistors in parallel, a safe margin coefficient of discharge withstand current should be considered according to the actual relative standard deviation of surge residual voltages of used ZnO varistors. View full abstract»

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  • An improved arc model before current zero based on the combined Mayr and Cassie arc models

    Publication Year: 2005 , Page(s): 138 - 142
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB) |  | HTML iconHTML  

    A computer model that describes the dynamic arc behavior in the high- and low-current regions before current zero is proposed. The model divides the current and voltage waveform in two regions. A differential equation for both regions which unifies current and voltage time derivatives is obtained by means of a generalized function method. The computer waveforms reproduced with the model show good agreement with measured results published in in the low and high current regions, but further comparison with other test measurements are required to know if the model has any feature of predictability. View full abstract»

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  • Calculation of transient puffer pressure rise takes mechanical compression, nozzle ablation, and arc energy into consideration

    Publication Year: 2005 , Page(s): 143 - 148
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (416 KB) |  | HTML iconHTML  

    Thermal puffer-type gas circuit breaker (GCB) has a high dielectric and current interruption capability. In order to design a good thermal puffer GCB, it is important to know the blast pressure for arc cooling. Although pressure calculation programs have been developed and used for design work, the basic characteristics, such as contribution of nozzle ablation gas to puffer pressure rise, amount of back flow gas to puffer chamber, and pressure distribution along gas passages during current interruption, are not well known. In this paper, pressure rise, mass flow, and temperature calculations were carried out using a new calculation model, which takes mechanical compression by puffer piston, nozzle ablation in the nozzle throat and arc energy into consideration. By analysis of the calculation results, we found the pressure rise mechanism is as follows. While fixed contact located in the divergent part of nozzle, all of the ablation gas generated from the nozzle wall cannot be exhausted from the nozzle and it leads to high-pressure generation in the nozzle throat. This pressure causes transfer of hot ablation gas back to the puffer chamber via gas passage. The puffer pressure increases thermally due to temperature rise by this mechanism. At a longer arcing time, as high puffer pressure was already established in the puffer chamber, the nozzle ablation gas cannot flow back to the puffer chamber. Besides as mass flow through nozzle is limited by low gas density, the puffer pressure rise is obtained by the mechanical compression of puffer piston. View full abstract»

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  • Deriving an equivalent circuit of transformers insulation for understanding the dielectric response measurements

    Publication Year: 2005 , Page(s): 149 - 157
    Cited by:  Papers (38)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (432 KB) |  | HTML iconHTML  

    Preventive diagnosis and maintenance of transformers have become more and more popular in recent times in order to improve the reliability of electric power systems. Dielectric testing techniques such as return voltage measurement (RVM) and polarization-depolarization current (PDC) measurement are being investigated as potential tools for condition assessment of transformer insulation. A better understanding and analysis of the dielectric test results are only possible with a clear understanding of the physical behavior of the insulation system in response to moisture and aging. A circuit model, which describes the dielectric behavior of the transformer's main insulation system, has been parameterized in this paper. The values of the parameters of the model have been identified from the dielectric tests. A correlation has been developed between the physical condition of the insulation and the equivalent model parameters that enable a clear and transparent interpretation of the dielectric test results. View full abstract»

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  • Sensitive online PD-measurements of onsite oil/paper-insulated devices by means of optimized acoustic emission techniques (AET)

    Publication Year: 2005 , Page(s): 158 - 162
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1440 KB) |  | HTML iconHTML  

    Recently developed monitoring-systems show the need as also the possibilities for online- and offline-onsite-diagnostics. The limit in sensitivity for electrical pd-measurements according to IEC 60270 which is reached using filters for sinusoidal disturbances and compensation for corona impulses is still not satisfactory. The acoustic partial discharge measurement (pd-measurement) is also a well known and reliable method often used by transformer manufacturers in testing. In laboratory setups a gain in sensitivity of the acoustic in comparison to the electrical pd measurements could be established. This is reached by adapting the sensors to the propagation path, a modern but moderately priced acquisition hardware and the introduction of new signal processing algorithms. The developed sophisticated measuring systems show remarkable results in online acoustic pd-measurements onsite. View full abstract»

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  • Development of a DC current-blocking device for transformer neutrals

    Publication Year: 2005 , Page(s): 163 - 168
    Cited by:  Papers (11)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (792 KB) |  | HTML iconHTML  

    In the early 1990s, Hydro-Que´bec undertook a joint project with GE to develop and commission a dc current-blocking series capacitor for the transmission lines forming part of its main power system in the area surrounding the grounding electrode of the Radisson HVdc substation. The aim of this project was to minimize the harmful effects of dc current flowing through the main network during the ground-return operating mode of the Radisson-Sandy Pond multiterminal HVdc link. With a view to having available technology applicable anywhere in the network, TransE´nergie and IREQ, two divisions of Hydro-Que´bec, later took part in the development of a dc current-blocking device that could be installed in transformer neutrals. This work was undertaken not only with immediate needs in mind but also to solve specific problems that could appear sporadically at different network locations. Tests on a prototype of the new blocking device were performed in the High Power Laboratory at IREQ, followed by tests on the preproduction unit, in accordance with the specified requirements. The neutral dc current-blocking device (NCBD) was then installed at a regional substation for a one-year operating period to verify its immunity under normal network events and switching conditions. During this period, no disruption to the smooth operation of the substation or protection of the ac system occurred. The NCBD operated correctly and suffered no fault or unsolicited operation. View full abstract»

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  • Fault diagnosis of a power transformer using an improved frequency-response analysis

    Publication Year: 2005 , Page(s): 169 - 178
    Cited by:  Papers (31)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (592 KB) |  | HTML iconHTML  

    A transformer is one of the most important units in power networks; thus, fault diagnosis of transformers is quite significant. In this paper, the frequency-response analysis, deemed as a suitable diagnostic method for electrical and/or mechanical faults of a transformer, is employed to make a decision over a defective phase. To deal with wideband frequency responses of each phase, a synthetic spectral analysis is proposed, which augments low- and medium-frequency components, and equalizes the frequency intervals of a resulting combined curve by a log-frequency interpolation. Furthermore, for discriminating a defective phase through computing overall amounts of deviation with other phases, the two well-known criteria and three proposed criteria are examined with experiment data. The overall diagnosis results show that the proposed criterion discriminates a defective phase with the highest average hit ratio among all of the provided criteria for selected faults. 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