By Topic

Popular Articles (March 2015)

Includes the top 50 most frequently downloaded documents for this publication according to the most recent monthly usage statistics.
  • 1. Battery chargers for electric vehicles

    Publication Year: 2000 , Page(s): 8 - 11, 18
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (332 KB)  

    This article presents a comparative study of the performance of two types of battery chargers being developed for electric vehicles. The first charger is a microprocessor-based ferroresonant battery charger, referred to as the ferroresonant charger. The power delivery section of this charger is a ferroresonant transformer, which exploits the saturation of magnetic materials through its capacitor winding to produce a well-regulated output that resembles a square wave. The control section periodically places a resistive load across the battery under charge that allows this change in resistance to be detected. A microprocessor controls the timing and executes the gating of the needed switches in the circuit and then gathers and analyzes data from the battery charge monitor circuit. The monitor circuit measures the voltage drop across the battery, which is proportional to the battery internal resistance when the load is introduced. The second charger is a multiphase AC-to-DC converter that employs two three-phase transformers to create twelve phases and is called the twelve-phase charger. One transformer primary is in the delta configuration, and the other transformer primary is in the wye configuration. The center-tapped secondaries create the twelve phases. Thyristors are used to control the output voltage of the charger through digital control of the firing angle. A microprocessor controls the charging profile of the battery. A motor-generator set is used to simulate the load to the charger for test conditions View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 2. Superconducting fault current limiters

    Publication Year: 2000 , Page(s): 15 - 18, 30
    Cited by:  Papers (34)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (752 KB)  

    Events in the power utility industry, such as deregulation, demands for better power quality and reliability, the advent of high temperature superconductivity, and the push to use technology to realize greater profits, have renewed interest in fault current limiters (FCL). Superconducting FCLs will become very important as the deregulation environment takes hold and utilities seek more efficient and cost-effective methods to couple grids, improve power quality, and delay expensive upgrades. The working principle and progress of superconducting FCLs is discussed in this article View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 3. Improved Dynamic Load Model for Power System Stability Studies

    Publication Year: 1982 , Page(s): 49 - 50
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (376 KB)  

    The behavior of the load model in power system stability studies has been shown by various investigators to be a very important factor in determining the stability of power system elements. Load models which are presently available in typical stability programs make it difficult if not impossible to model the actual dynamics of power system load. Present load models allow easy static representations, but require detailed individual dynamic models such as induction or synchronous motor models. Thus a simple load model that can represent power system composite load dynamics will be a valuable tool in the stability study Presented herein is a second order state space load model which can represent power system composite load dynamics. In addition, the parameters of this state space load model can be identified from actual system load measurements by a weighted least squares parameter identification process. Several authors recognized the significance of load behavior to changes in voltage as long as 25 years ago. However, most of the attention in stability studies has been directed toward improved generator and control system models. Until recently, little modeling has been considered necessary for power system loads since the effects of load models in stability studies were considered only secondary. At present the load representation in typical stability programs is limited to a static load model where the load is represented as constant MVA, constant current, constant impedance, or some combination of the three. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 4. Superconducting magnetic energy storage

    Publication Year: 2000 , Page(s): 16 - 20
    Cited by:  Papers (25)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (571 KB)  

    Superconducting magnetic energy storage (SMES) is an energy storage technology that stores energy in the form of DC electricity that is the source of a DC magnetic field. The conductor for carrying the current operates at cryogenic temperatures where it is a superconductor and thus has virtually no resistive losses as it produces the magnetic field. The overall technology of cryogenics and superconductivity today is such that the components of a SMES device are defined and can be constructed. The integrated unit appears to be feasible for some utility applications at a cost that is competitive with other technologies. SMES is the only technology based on superconductivity that is applicable to the electric utilities and is commercially available today. In addition to today's power quality application, the historical development of SMES starting with the concept of very large plants that would store hundreds of megawatt hours of energy and were intended for diurnal load leveling are described. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 5. Analysis of line compensation by shunt-connected FACTS controllers: a comparison between SVC and STATCOM

    Publication Year: 1999 , Page(s): 57 - 58
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (180 KB)  

    A novel method for the analysis of the effectiveness of an SVC and a STATCOM of the same kVAr rating for first-swing stability enhancement is presented and the concept is demonstrated with a numerical example. The analysis shows that the STATCOM is superior to the SVC for first-swing stability enhancement View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 6. Role of HVDC transmission in future energy development

    Publication Year: 2000 , Page(s): 10 - 25
    Cited by:  Papers (23)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1476 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 7. Techniques for the Steady State Representation of Unbalanced Power Systems, PART I: A Systematic Building Block Approach to Network Modeling

    Publication Year: 1985 , Page(s): 42
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (197 KB)  

    The effects of interphase coupling in multiphase power systems become important in the presence of network topology imbalance and unbalanced phase loadings. Currents that flow in the earth can have significant effects on the system's behavior. Both of these effects of imbalance must be accounted for in an accurate model of a multiphase system. A step-by-step procedure for unbalanced power system modeling is presented. The procedure relies upon linear graph theory and produces a multiport model which is a generalization of the well-known bus admittance model. This paper reviews some important results of linear graph theory and gives sufficient detail that the procedure can be followed without extensive use of the references (whose nomenclatures differ). Mutual coupling effects, the effects of neutral and static conductors, the finite conductivity of earth, and various component models are considered. A companion paper describes a procedure for reducing the order of the power system model. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 8. Thermal Protection of Induction Motors Enhanced by Interactive Electrical and Thermal Models

    Publication Year: 1984 , Page(s): 48
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (136 KB)  

    Models are of interest to application engineers because they identify important electrical, thermal, and mechanical interactions in an induction motor. They provide a format for the parameters which must be obtained. The loading and terminal conditions can then be specified and the model state equations used to obtain the thermal limit curves and, what is more important, the time solution for current, torque, speed, and the temperatures of the rotor and stator. Adequate protection of induction motors is routinely achieved via locked-rotor, phase unbalance, and overload protection. However, conditions of changing load torque, frequent starts, temporary phase unbalance and high inertia loading must often be tolerated. Designing protective schemes for these conditions using conventional relays is difficult and sometimes impossible. Motor protection is primarily a temperature estimation problem. Recognizing that good electrical and thermal models exist leads to their adoption for motor protection so that the heating and cooling process is well represented for virtually all loading and terminal conditions. This paper first reviews electrical, thermal, and mechanical models. Their parameters are discussed and a novel technique is introduced for accommodating the frequency dependent skin effect of the rotor resistance using a simple speed estimation algorithm. The correlation with protection practice is established by using the models to obtain the thermal limit curves for a motor including the relatively recent rotor accelerating time limit. The models are then used to analyze conditions of locked rotor, high inertia starting and overload torque. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 9. Technical Council Generator Ground Fault Protection Using Overcurrent, Overvoltage, and Undervoltage Relays

    Publication Year: 1984 , Page(s): 16 - 28
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2493 KB)  

    This paper describes the protective relaying schemes employed by Georgia Power Company to protect synchronous generators from single-phase-to-ground faults. Three types of relays are connected in the secondary of a distribution grounding transformer. These include a conventional electro-mechanical overcurrent relay with time overcurrent unit and instantaneous overcurrent unit, a solid-state overvoltage relay (with timing module) tuned to reject frequencies near 180 hertz, and a solid-state undervoltage relay (with timer) tuned to reject frequencies near 60 hertz present at the generator neutral. The proper method of selecting the generator grounding components and protective relays is described, and detailed setting instructions for all relays are also included. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 10. Voltage Stability Evaluation Using Modal Analysis

    Publication Year: 1992
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (237 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 11. Estimating the Voltage Stability of a Power System

    Publication Year: 1986 , Page(s): 72
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (915 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 12. Effects of FACTS controller line compensation on power system stability

    Publication Year: 1998 , Page(s): 55 - 56
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB)  

    In this letter, the effects of line compensation of an SMIB power system using FC-TCR type TCSC or SVC for transient stability enhancement are analyzed. In particular, a novel method for analysis of line compensation by an SVC is presented. The maximum power transfer, Pemax for line compensation by FACTS controllers can be written in the form Pemax=Pmax/(1-k) where Pmax is the maximum power transfer for the uncompensated line and k is the degree of compensation. The analysis revealed that the effectiveness of the SVC for stability enhancement is increased if the degree of compensation of the line is increased View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 13. Second Benchmark Model for Computer Simulation of Subsynchronous Resonance IEEE Subsynchronous Resonance Working Group of the Dynamic System Performance Subcommittee Power System Engineering Committee

    Publication Year: 1985 , Page(s): 34
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (155 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 14. Power quality compensation using universal power quality conditioning system

    Publication Year: 2000 , Page(s): 58 - 60
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (192 KB)  

    The aim of this letter is to present a universal power quality conditioning system (UPQS) named after a unified power quality conditioner (UPQC), which is extended by adding a shunt active filter at the load side. Its main purpose is to compensate for supply voltage and load current imperfections, such as sags, swells, interruptions, imbalance, flicker, harmonics, reactive currents, and current unbalance. Converter and control analysis is presented together with results showing the UPQS modes of operation. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 15. High Power Electronics and flexible AC Transmission System

    Publication Year: 1988 , Page(s): 3 - 4
    Cited by:  Papers (87)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (245 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 16. History of Transformers

    Publication Year: 1996
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1128 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 17. Guidelines for Modeling Power Electronics in Electric Power Engineering Applications

    Publication Year: 1997 , Page(s): 71
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (135 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 18. A power quality monitoring system: a case study in DSP-based solutions for electric power industry

    Publication Year: 1999 , Page(s): 47 - 50
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (536 KB)  

    The purpose of this study is to develop and implement a power quality monitoring system that will enable power quality engineers to conduct diagnostic testing in the field. The study is limited to the implementation of hardware and software required to process the analog signals received. A real-time monitoring system that can be used to perform automated power quality testing is described. The system is centered on a digital signal processor (DSP) interfaced to a personal computer (PC). The test signal is input to the system through the A/D board. The signal is analyzed in real-time in the DSP, and the results are transferred to the PC through the communication interface. The PC presents the results and interacts with the user. This system can be used to perform onsite power quality studies View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 19. Power System Control and Stability [Boooks and Reports]

    Publication Year: 1995
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (140 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 20. A new method for determining reference compensating currents of the three-phase shunt active power filter

    Publication Year: 2001 , Page(s): 63 - 65
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (152 KB) |  | HTML iconHTML  

    Among various solutions to electric power quality problems, the use of a shunt active power filter (SAPF) has been proven as an effective method to compensate reactive power and to mitigate harmonic currents of nonlinear loads. When designing a SAPF, it is crucial to generate reference currents for determining actual compensating current injections to the point of common coupling. In contrast to the conventional instantaneous reactive power theory that needs coordinate transformations, the new method proposed in this paper is to determine reference compensating currents based on the balance of the instantaneous reactive and active power generated in the SAPF. It is shown that the proposed method is suitable for reactive and harmonic power compensation by using a SAPF. In addition to maintaining the sinusoidal source currents, this method also eliminates the need for installing an energy storage device for reactive power compensation as well as the DC source for the harmonic compensation in the active power filter. Therefore, a simpler design of the SAPF with the minimal line losses can be expected View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 21. Understanding Power System Hannonics

    Publication Year: 2001 , Page(s): 8 - 11
    Cited by:  Papers (59)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2053 KB) |  | HTML iconHTML  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 22. Generalized one-machine equivalents in transient stability studies

    Publication Year: 1998 , Page(s): 50 - 52
    Cited by:  Papers (22)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (428 KB)  

    We consider an emerging class of hybrid methods which basically reduce a multimachine power system into a one-machine infinite bus (OMIB) equivalent and then apply the suitably adapted equal-area criterion. A time-domain transient stability program is used to refresh the OMIB parameters at each time step to arrive at “generalized” OMIBs. The scheme is able to provide accurate real-time transient stability assessment under any power system modeling, any stability scenario and any instability mode. On the other hand, similar generalized OMIBs may potentially be designed for real-time transient stability emergency control, by using real-time measurements. The purpose of this letter is to highlight some unique enhancements to the class of methods offered by the generalized OMIB concept View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 23. HVDC Light: A New Technology for a Better Environment

    Publication Year: 1998 , Page(s): 19 - 20
    Cited by:  Papers (47)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (316 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 24. Technique for assessment of voltage stability in ill-conditioned radial distribution network

    Publication Year: 2001 , Page(s): 58 - 60
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (156 KB) |  | HTML iconHTML  

    A technique is proposed in this letter to study the voltage collapse situation in a radial distribution network. The radial distribution network has been reduced to a single line equivalent circuit and then represented through a π network. A stability index is developed that indicates the severity of the loading situation of the system. The index can have a maximum value of one (1.00) when the system is at the point of collapse and a minimum value of zero (0) when there is no load in the system. Voltage collapse can be assessed based on the value of the developed index. If the system yields a value exceeding its maximum limit of stability index (1.00) it indicates a voltage collapse situation. The proposed technique is tested on a practical system of a 12-bus radial system (main feeders only) and on a 27-bus radial distribution system with laterals. The results obtained are encouraging and indicate that the technique has the potential to be used as a tool for system monitoring and future load planning View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 25. Geomagnetic Storms and Their Impact on Power Systems

    Publication Year: 1996
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (780 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 26. Power Quality Engineering

    Publication Year: 2001 , Page(s): 5 - 7
    Cited by:  Papers (25)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (141 KB) |  | HTML iconHTML  

    Power system restructuring requires expanding unused potentials of transmission systems due to environmental, right-of-way and cost problems, which are major hurdles for power transmission network expansion. FACTS devices can be an alternative to reduce the flows in heavily loaded lines, resulting in an increased loadability, low system loss, improved stability of the network, reduced cost of production, and fulfilled contractual requirements by controlling the power flows in the network. This letter suggests first, the few optimal locations of FACTS devices and then determines the best optimal location in order to reduce the production cost along with the device cost. The allocation and requirement are also discussed. The effectiveness of the proposed methods is demonstrated on an IEEE 14-bus system. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 27. FACTS technology development: an update

    Publication Year: 2000 , Page(s): 4 - 9
    Cited by:  Papers (39)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB)  

    This overview of the FACTS program sponsored by EPRI identifies the significant challenges and the adopted technology-based solutions that have been developed. FACTS technology has been successfully demonstrated and continues to be implemented at transmission locations in the United States. A STATCOM, UPFC, and convertible static compensator are discussed. The installed FACTS controllers have provided new possibilities and unprecedented flexibility aiming at maximizing the utilization of transmission assets efficiently and reliably. As the development and implementation of FACTS controllers evolve, there will be a need for an overall controller "hierarchical" logic to optimize transmission system operations View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 28. The IEEE Reliability Test System???Extensions to and Evaluation of the Generating System

    Publication Year: 1986 , Page(s): 24
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1029 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 29. Development and Interrupting Tests on 250KV 8KA HVDC Circuit Breaker

    Publication Year: 1985 , Page(s): 42 - 43
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1763 KB)  

    This paper describes the circuit and component selections, development and equivalent circuit test results on an HVDC circuit breaker for an HVDC transmission line. A puffer type SF6 gas interrupter for AC circuit breakers is utilized for interrupting DC current with injection of high-frequency inverse current from a commutating capacitor precharged to HVDC line voltage. Also, the effectiveness of application of the HVDC breaker to an HVDC system with two parallel transmission lines is demonstrated through the EMTP simulation. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 30. Wind Turbine Generator Interaction With Diesel Generators on an Isolated Power System

    Publication Year: 1984 , Page(s): 28 - 29
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (362 KB)  

    The Block Island Power Company (BIPCO), on Block Island, Rhode Island, operates an isolated electric power system consisting of diesel generation and an experimental wind turbine. The 150-kW wind turbine, designated MOD-OA by the U. S. Department of Energy is typically operated in parallel with two diesel generators to serve an average winter load of 350 kW. As part of an experimental program to evaluate wind turbine generator performance on the isolated diesel power system, the recordings from an extensive data measurement effort were reviewed and analyzed to define the nature of the dynamic interaction effects. The data were collected over a three-month period on the system to which the DOE/NASA experimental wind turbine was connected. During this time, the diesel units were lightly loaded resulting in up to 60 percent of the total load demand being supplied by the MOD-OA in periods of severely gusting winds. In three of the modes of normal MOD-OA operation. startup???synchronization, shutdown/cutout, and continuous fixed pitch running???power, frequency and voltage transients were comparable with those produced by typical load changes on the diesel system alone. In the fourth mode, variable pitch (constant power) control, a significant reduction in system damping sometimes occurred which gave rise to increased frequency and voltage perturbations under gusty wind conditions. Based on a linear model of the system it is shown that changes in control system settings could be made to improve damping. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 31. Impact of Grounding System Design on Power Quality

    Publication Year: 2001 , Page(s): 3 - 7
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5720 KB) |  | HTML iconHTML  

    Retiring in 1924, at the age of 74, Edward Weston could look back with satisfaction at the accumulation of over 300 patents, many honors, and a thriving company, the Weston Electric Instrument Corporation. He had reached a goal that few inventors in history have ever reached. He had become a criterion in a great new art, a standard of reference for everyone else. Although his competitors made and sold instruments for as little as one-third his own prices, he still sold more than they did. So good was his product that he scaled each instrument when it was made, guaranteeing its accuracy as long as nobody broke the seals and tampered with the mechanism. Much of his accomplishment was directly related to his personality. He was persistent, single-minded, a skillful inventor, and sometimes aloof, and he loved a good fight, especially in the courtroom when defending his patents. This article briefly outlines the life and work of Weston. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 32. System Design Considerations for Implementing Performance and Service Tests on Class 1E Batteries in Accordance with IEEE 450-1980

    Publication Year: 1982 , Page(s): 39 - 40
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (446 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 33. Distribution Transformer No-Load Losses

    Publication Year: 1985 , Page(s): 44 - 45
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (326 KB)  

    The no-load losses measured during the test are assumed to consist essentially of core losses, i.e., hysteresis and eddy current losses. Eddy current losses deduced from experiments are generally higher than those calculated from the classical theory. The difference between these two quantities is called the ``anomalous'' loss. A brief review of these losses is given, although in most of the analyses the no-load losses are assumed to consist of hysteresis and eddy current losses. The calculation of losses in magnetic materials for distorted flux waveforms is rather complex. Several attempts have been made in recent years to convert the losses measured under non-sinusoidal excitation conditions to a common base of losses under sinusoidal excitation conditions. A brief review of the work done by previous investigators and the correction methods they proposed are given. The effect of temperature on no-load losses is illustrated through two sets of experiments. In the first set, hysteresis loss and total loss on Epstein samples of 12 mil RGO and HGO steels were obtained as a function of temperature in the range of 20??C to 200??C. The results showed that hysteresis loss is constant with temperature, and eddy current loss decreased with increasing temperature. In the other set, no-load losses of a number of distribution transformers, ranging in size from 10 through 50 KVA, were measured in the temperature range of 20??C to 100??C. The results showed that the losses decreased with increasing temperature. Results for both sets of experiments are illustrated in Fig. 1. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 34. Development of a New Type Fault Locator Using the One-Terminal Voltage and Current Data

    Publication Year: 1982 , Page(s): 59 - 60
    Cited by:  Papers (1)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1232 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 35. Substation battery options: present and future

    Publication Year: 2000 , Page(s): 4 - 7
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (284 KB)  

    Whenever a new battery type is considered, it is important to use life-cycle cost analysis that weighs all costs associated with battery ownership over a certain period of time, including the replacement of shorter-life batteries and all associated maintenance and testing activities. This article discusses the benefits and drawbacks of some of the potential alternatives to vented lead-acid batteries in substation service. These include VRLA, nickel-cadmium (Ni-Cd), nickel-metal hydride (Ni-MH), lithium-ion (Li-ion) and lithium polymer (Li-polymer). The aim of the article is to provide an overview of ongoing battery development work and an idea of the time-frame for commercial availability View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 36. Axial-Field Electrical Machines???Design and Applications

    Publication Year: 1987 , Page(s): 49 - 50
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1008 KB)  

    Axial-field electrical machines (AFM's) offer an alternative to the conventional radial-field machines (RFM's). In the axial-field machine, the airgap flux is axial in direction and the active current-carrying conductors are radially positioned. This paper presents the design characteristics, special features, manufacturing aspects, and potential applications for axial-field electrical machines. The experimental results from several prototypes, including de machines, synchronous machines, and single-phase machines are given. The special features of the axial-field machine, such as its planar and adjustable airgap, flat shape, ease of diversification, etc., enable axial-field machines to have distinct advantages over conventional machines in certain applications, especially in special purpose applications. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 37. Nikola Tesla and the Wireless Transmission of Energy

    Publication Year: 1982 , Page(s): 58 - 59
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1437 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 38. Advanced clean coal technologies

    Publication Year: 2001 , Page(s): 6 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (532 KB) |  | HTML iconHTML  

    In this paper, the author argues that, although coal may be an interim solution, the development of technologies providing effective use of coal is important to bridge the gap between present and future energy supply situations View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 39. Dynamic Behavior of a Class of Photovoltaic Power Systems

    Publication Year: 1983 , Page(s): 36 - 37
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (438 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 40. A power quality and reliability index based on customer interruption costs

    Publication Year: 1999 , Page(s): 59 - 61
    Cited by:  Papers (4)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (316 KB)  

    Standard reliability indexes such as SAIDI ignore the variation in interruption costs with customer type. Thus, expenditure decisions driven by these indices that impact reliability, will not lead to the optimum improvement in value of service to customers. An index equal to customer interruption costs divided by energy sales (CICs/kWh) overcomes this deficiency. It is equally useful for identifying best-business-value solutions to power quality problems. It enables a supplier to decide which portfolio of projects (affecting power quality, or reliability, or neither) earns the highest return on investment, and allows a direct comparison of its value-creation record with that of its competitors View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 41. Three Dimensional Flux Calculation on a Three-Phase Transformer

    Publication Year: 1986 , Page(s): 47 - 48
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1916 KB)  

    Increases in the ratings of large power transformers have demanded more accurate methods of predicting leakage fields which give rise to excessive losses in the devices. This paper addresses the issue, giving the development of a technique which can be used with minimal computing power to determine the distribution of the magnetic fluxes. Estimates for the additional stray load losses in the iron parts can be calculated with reasonable accuracy after the flux distribution has been found. For developing large transformers and reactors, it is necessary to know the distribution of the magnetic leakage field to calculate the electro-dynamic forces and the stray losses due to eddy currents in the winding conductors and in steel parts such as core, tank, pressing beams, etc. In general, the magnetic field in the transformer is calculated using the assumption that the structure is two-dimensional. But actual transformers are three-dimensional. Thus, the customary two-dimensional approximations are inadequate. In this paper, the three-dimensional magnetic flux distribution on the tank wall of a three phase transformer has been calculated. In order to perform the calculation, a finite element scheme has been adopted to obtain a two-dimensional solution at 15 meridian planes of the transformer coil of a single phase transformer for any arbitrary value of current density. Using the actual values of current densities, the magnetic field has been computed for each phase at two selected instants of time in the cycle. Then, the results are manipulated to obtain an overall solution. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 42. Static Synchronous Series Compensator: A Solid-State Approach to the Series Compensation of Transmission Lines

    Publication Year: 1997 , Page(s): 62
    Cited by:  Papers (5)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (159 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 43. An analytical solution to the economic dispatch problem

    Publication Year: 2000 , Page(s): 52 - 55
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB)  

    This letter treats the basic problem of economic operation of power systems and presents a mathematical derivation that proves that the classic economic dispatch (ED) problem, with quadratic-convex cost functions, can be solved analytically, i.e., without any approximations or need for numerical iterative optimization algorithms. Duality theory is employed to determine both the exact primal and exact dual solutions. All this requires, at most, are 2n function evaluations. It is stated, therefore, that the use of an ED model as an optimization-based electricity auction does not cause any conflict of interest View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 44. Air Clearances for Electric Railways: A Study of the Breakdown Voltage of Rod-Plane Gaps in a Variety of Atmospheric Conditions

    Publication Year: 1985 , Page(s): 47 - 48
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (440 KB)  

    A study has been made of the electric strength of air gaps for the Canadian 50 kV railway system. Tests were made on a rod-plane gap using switching and lightning impulses, 60 Hz and combined impulse and 60 Hz waves. The effects of clean and salt-water fog and dust contamination as well as exhaust fumes were investigated. The influence of water droplets falling from one electrode was also determined. Of these, the most important factor in reducing the ac strength of the air gap was exhaust fumes, which brought down the strength by as much as 20 percent. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 45. A United Approach to Optimal Real and Reactive Power Dispatch

    Publication Year: 1985 , Page(s): 42 - 43
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (513 KB)  

    This paper presents a unified method for optimal real and reactive power dispatch for the economic operation of power systems. As in other methods, the problem is decomposed into a P-optimization module and a Q-optimization module, but in this method both modules use the same generation cost-objective function. The control variables are generator real power outputs for the real power module; and generator reactive power outputs, shunt capacitors/reactors, and transformer tap settings for the reactive power module. The constraints are the operating limits of the control variables, power line flows, and bus voltages. The optimization problem is solved using the gradient projection method (GPM) which is used for the first time in the power systems study. The GPM allows the use of functional constraints without the need of penalty functions or Lagrange multipliers among other advantages. Mathematical models are developed to represent the sensitivity tivity relationships between dependent and control variables for both, real and reactive power, optimization modules, and thus eliminate the use of B-coefficients. Results of two test systems are presented and compared with conventional methods. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 46. Applications of superconductivity to electric power systems

    Publication Year: 2000 , Page(s): 4 - 7
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (260 KB)  

    The interest in superconducting systems stems from their promise to be more efficient, smaller, and lighter than those made from conventional conductors. The types of applications in which superconductivity has the potential to be effective in an electric power system can be separated into two general classes. The first type includes those technologies in which superconductivity is simply a replacement of existing resistive materials, for example, cables, motors, generators, and transformers. The second type includes technologies that will be enabled by superconductivity and that have little or, at most, limited capability if conventional resistive or other materials are used. Examples are superconducting magnetic energy storage (SMES) and large fault current limiters (FCL). Before looking at the applications under development the article discusses the discovery and development of superconductivity View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 47. Solar Energy

    Publication Year: 1982 , Page(s): 8 - 12
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1151 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 48. Volt/Var Control on Distribution Systems with Lateral Branches Using Switched Capacitors and Voltage Regulators, Part II: The Solution Method

    Publication Year: 1985 , Page(s): 53
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (208 KB)  

    In this paper the optimal solutions of the following two decoupled problems are given on the basis of the model presented in Part I; (i) The capacitor (var) problem: determination of the locations, sizes and the real-time control of n ON/OFF switched and fixed shunt capacitors, (ii) The regulator (volt) problem: determination of the locations and real-time control of minimum number of voltage regulators. The objective in both problems is to minimize the peak power and the energy losses and to provide smooth voltage profile along the distribution system with lateral branches. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 49. Moisture Equilibrium Charts for Transformer Insulation Drying Practice

    Publication Year: 1984 , Page(s): 59
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (199 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 50. Designing and testing low-resistance grounding systems

    Publication Year: 2000 , Page(s): 19 - 21
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (160 KB)  

    A properly designed ground system is an integral part of a site and should be regarded as highly as all of the other equipment-critical components. Such a system will play a major role in obtaining and maintaining a well-protected and efficient facility. This may be achieved with traditional methods and/or an enhanced system with electrolytic electrodes with carbon backfill. The article briefly discusses design and testing of a system including soil resistivity measurement. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.