Showing papers in "IEEE Power & Energy Magazine in 2000"
TL;DR: 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 as discussed by the authors.
Abstract: 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.
169 citations
TL;DR: In this paper, a hybrid GA method was used to solve optimal power flow (OPF) in power systems incorporating flexible AC transmission systems (FACTS) to minimize the total generation fuel cost and keep the power flows within the security limits.
Abstract: This letter presents a hybrid genetic algorithm (GA) method to solve optimal power flow (OPF) in power systems incorporating flexible AC transmission systems (FACTS). In the solution process, GA is integrated with conventional OPF to select the best control parameters to minimize the total generation fuel cost and keep the power flows within the security limits. A case study using an IEEE test system is presented to demonstrate its applicability.
162 citations
TL;DR: This overview of the FACTS program sponsored by EPRI identifies the significant challenges and the adopted technology-based solutions that have been developed and a STATCOM, UPFC, and convertible static compensator are discussed.
Abstract: 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.
159 citations
TL;DR: In this paper, the working principle and progress of superconducting fault current limiters (FCLs) is discussed, as well as their application in the power utility industry, such as deregulation, demands for better power quality and reliability, and the advent of high temperature superconductivity.
Abstract: 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.
150 citations
118 citations
TL;DR: A generic planning framework to meet the requirements of distribution companies in the United Kingdom with particular regard to embedded generation is investigated, developed from an extensive survey of planning methodologies.
Abstract: Recent IEEE publications have been of great interest to those who have been investigating the requirements for power system planning in restructured, unbundled and competitive electricity markets. In particular, the increased uncertainty regarding generator siting and timing are problems that will tend to increase as competition in generation increases. The authors have been investigating a generic planning framework to meet the requirements of distribution companies in the United Kingdom with particular regard to embedded generation. The generic framework has been developed from an extensive survey of planning methodologies, with reference to standard industry planning practices and in recognition of the set of issues regarding embedded generation that require to be addressed through evaluation.
85 citations
TL;DR: In this paper, a comparative study of the performance of two types of battery chargers being developed for electric vehicles is presented, including a microprocessor-based ferroresonant battery charger and a multiphase AC-to-DC converter.
Abstract: 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.
82 citations
TL;DR: In this article, the authors presented a universal power quality conditioning system (UPQS) named after a unified power quality conditioner, which was extended by adding a shunt active filter at the load side.
Abstract: 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.
81 citations
TL;DR: In this article, the authors consider various options that are available, point out the less likely, and highlight those that have the potential of achieving major improvements in the next two decades.
Abstract: The assets and working philosophy of individual utilities will in large measure be reflected by the modernization of their power systems in the next 2 decades. The power system of the future should enable utilities to: be more competitive with their overall strategies; provide better service; better manage their assets; extend equipment life; improve diagnostics; and develop reliability-centered maintenance. In looking ahead at the next 2 decades, we consider various options that are available, point out the less likely, and highlight those that have the potential of achieving major improvements. Although the next 20 years is a little soon for dispersed generation to have a significant impact, some of the implications of dispersed generation are considered. The following topics are covered in this paper: transmission and distribution developments; comparison of overhead and underground power delivery; the pros and cons of underground delivery; superconducting power transmission including cables; and cryoresistive delivery including conventional cryoresistive delivery, hyperconductivity and metal-plated graphite fibres.
69 citations
TL;DR: Based on stochastic programming, from the viewpoint of operational planning, a novel methodology is proposed to evaluate the available transfer capability (ATC) of prescribed interfaces in interconnected power networks.
Abstract: Based on stochastic programming, from the viewpoint of operational planning, a novel methodology is proposed to evaluate the available transfer capability (ATC) of prescribed interfaces in interconnected power networks. Recognizing the uncertainties of power systems, an effective stochastic model of ATC evaluation is formulated, in which the availability of generators and circuits as well as load forecast error are considered as random variables. A hybrid method that takes advantage of both two-stage stochastic programming with recourse (SPR) and chance constrained programming (CCP) is proposed to deal with this complex problem, which includes both discrete and continuous variables. Case studies with a reduced practical system are presented. The performance clearly illustrates the effectiveness of the proposed methodology.
53 citations
TL;DR: In this paper, an approach for fitting saturation characteristic and hysteresis using arctangent functions is presented, based on measurements of the magnetizing curve of the ferromagnetic material.
Abstract: In this letter an approach for fitting saturation characteristic and hysteresis using arctangent functions is presented. It has direct application to modeling transformers and electric machines. The approach is based on measurements of the magnetizing curve of the ferromagnetic material. The analytical form of the characteristic can be completely described by only three parameters. These three parameters are enough to take into account: the slope of the linear region, the position of the knee, and the saturating slope. The appropriate selection of these parameters allows the fitting of a wide class of magnetizing characteristics in simulation programs.
TL;DR: In this article, the Hamiltonian equation for a power system with excitation control was derived and a modified energy-based Lyapunov function was presented for fast transient stability analysis of the controlled power systems.
Abstract: This letter first derives the Hamiltonian equation for a power system with excitation control. A modified energy-based Lyapunov function is then presented for fast transient stability analysis of the controlled power systems.
TL;DR: This letter 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.
Abstract: 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.
TL;DR: A framework for real-time congestion management under a marker structure similar to the newly proposed UK trading arrangement is presented in this letter, in which not only resources in balancing market but also some bilateral contracts can be dispatched if necessary.
Abstract: A framework for real-time congestion management under a marker structure similar to the newly proposed UK trading arrangement is presented in this letter, in which not only resources in balancing market but also some bilateral contracts can be dispatched if necessary. The linearized model of a modified optimal power flow (OPF) is proposed to implement such a framework. A 5-bus test system is used to illustrate the effectiveness of the proposed method.
TL;DR: The article discusses the discovery and development of superconductivity and the applications under development, including superconducting magnetic energy storage (SMES) and large fault current limiters (FCL).
Abstract: 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
Journal Article•
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TL;DR: In this article, the authors elucidate on some potential systems benefits and provide an update of progress in major high-temperature superconductor (HTS) transformer development programs worldwide.
Abstract: The paper elucidates on some of the potential systems benefits and provides an update of progress in major high-temperature superconductor (HTS) transformer development programs worldwide. It begins with background sections on earlier low-temperature-superconductor (LTS) transformer developments and on transformer losses and efficiencies and their influence on total owning costs (TOC) as one of the major drivers that may determine the success and broad acceptance of HTS transformers for power applications.
TL;DR: In this article, the detection of air gap eccentricity based on hearing damage in 5 hp induction machines is addressed, where the faulty condition of the bearing is caused by accelerated aging processes in seven aging cycles.
Abstract: This study addresses the detection of air-gap eccentricity based on hearing damage in 5 hp induction machines. The faulty condition of the bearing is caused by accelerated aging processes in seven aging cycles. For the faulty case, the spectra of vibration signals are computed for initial and final aging processes under 100% load condition. Subsequently, the spectra of the current signals for a single phase are also obtained for the initial and aged cases and cross-power spectral coherences between the vibration and current signals are computed.
TL;DR: In this paper, the authors investigated the impact of incorporating dynamic security considerations in an open market environment and proposed an approach to reschedule real power generation along with curtailment of real power loads/transactions to make the system dynamically secure after a fault.
Abstract: Security and reliability are major concerns in the deregulated and unbundled electricity supply industry due to the increased number of market participants and the changing demand patterns. This letter presents an approach and investigates the impact of incorporating dynamic security considerations in an open market environment. It is possible to reschedule the real power generation along with curtailment of real power loads/transactions to make the system dynamically secure after a fault. A conceptually plausible and computationally feasible approach for the solution of this problem has been developed for a system with a mix of pool and contract dispatches.
TL;DR: The discovery of high-temperature superconductivity (HTS) in 1986-1988 rekindled interest in superconducting power transmission cables and many projects are underway around the world to study the use of HTS power transmission cable.
Abstract: The discovery of high-temperature superconductivity (HTS) in 1986-1988 rekindled interest in superconducting power transmission cables. Many projects are underway around the world to study the use of HTS power transmission cables. The siting and environmental issues facing the expansion of transmission capacity have become increasingly more difficult with time. The HTS power cable may be able to address some of these issues, especially in urban areas, where HTS retrofits of existing conventional cables can increase capacity substantially without increasing the footprint of the cable right of way. Several of the cable projects employing HTS are discussed in this article.
TL;DR: In this paper, the authors considered the multi-year transmission expansion planning model HIPER (acronym of its name in Spanish: "Herramienta Interactiva para la Planeacion de la Expansion de la Red"), developed for application in deregulated environments.
Abstract: This letter considers the multiyear transmission expansion planning model HIPER (acronym of its name in Spanish: "Herramienta Interactiva para la Planeacion de la Expansion de la Red"), developed for application in deregulated environments. HIPER allows transmission planning under great uncertainties, such as the generation expansion, by defining strategic scenarios to reflect the possible future evolution of the generation system and the incorporation of a decision analysis scheme to minimize the risk of the proposed plan. An example case illustrates how HIPER can be applied to propose a transmission expansion plan, which is robust enough in the face of the uncertainty in the generation expansion.
TL;DR: In this paper, a simple model of nonlinear magnetization characteristics of a switched reluctance motor (SRM) is presented, where the flux linkage is given as a continuous function of phase current and rotor position.
Abstract: This letter presents a simple model of nonlinear magnetization characteristics of a switched reluctance motor (SRM). The flux linkage is given as a continuous function of phase current and rotor position. This allows a mathematical formula to be found for the instantaneous torque. The model is valuable for computer-aided designs, especially for sizing and initial estimates where accuracy can be traded with time saving. The model was implemented to verify its degree of accuracy. The simulation program has the ability to calculate numerous parameters that can be very useful for quick estimates of the efficiency of a particular SRM drive or for motor selection.
TL;DR: The first mixed-gas-insulated power transmission line in the world successfully completed its field trials with an endurance test in early 1999 as discussed by the authors, and the most important aim in the further development of tubular conductors for long-distance power transmission was to reduce costs so that they can be used economically over distances of up to several kilometers.
Abstract: Gas-insulated transmission lines (GIL) are a further development of the tubular conductor intended for long distances and are especially suitable for connecting conurbations to centers of power supply. They are also as "invisible" as ordinary power cables as well as having a number of other advantages. The first mixed-gas-insulated power transmission line in the world successfully completed its field trials with an endurance test in early 1999. The most important aim in the further development of tubular conductors for long-distance power transmission was to reduce costs so that they can be used economically over distances of up to several kilometers. This has now been achieved. The system costs of the gas-insulated transmission lines developed by Siemens are now only a factor of 8 or 10 above those of overhead power lines, down from a factor of 30. Now the GIL has reached the order of magnitude to be accepted by utilities if an overhead line must be brought underground. The basis of this reduction in costs was: adaptation of installation techniques similar to those used in laying pipelines; simplification and standardization of individual components; and use of a sulfur hexafluoride (SF/sub 6/) and nitrogen (N/sub 2/) gas mixture. In the past, pure SF/sub 6/ has been the most widely used gas for tubular conductors, most of which have been incorporated into substations.
TL;DR: In this article, the authors argue that the deregulation of the electric utility industry, coupled with the emergence of a knowledge-based information economy, is a double engine that makes this the most energized time ever to be in the electric business.
Abstract: The author argues that the deregulation of the electric utility industry, coupled with the emergence of a knowledge-based information economy, is a double engine that makes this the most energized time ever to be in the electric business.
TL;DR: The US Federal Energy Regulatory Commission (FERC) has changed its world as discussed by the authors, and its final rule on regional transmission organizations (RTOs) was published on 20 December 1999, and it followed this with Order 2000-A, which responded to requests for rehearing from many parties with "We meant what we said".
Abstract: The US Federal Energy Regulatory Commission (FERC) has changed its world. On 20 December 1999, it issued Order 2000, its final rule on regional transmission organizations (RTOs). On 25 February 2000, it followed this with Order 2000-A, which responded to requests for rehearing from many parties with "We meant what we said", and it also clarified a few fine points. Order 2000 calls for, but does not quite require, companies owning transmission systems to put the grid under the control of RTOs. FERC requires transmission-owning companies under its jurisdiction to file certain papers by late 2000 or early 2001. These papers can be either proposals to form RTOs or progress reports on the development of RTO proposals. RTOs will have sole responsibility for operation and expansion of the transmission system, maintaining short-term reliability, establishing and managing tariffs, and responding to requests for service.
TL;DR: In this paper, a unified exposition of various definitions of reactive power is presented, in particular, a comparative frequency-domain analysis of definitions used in power system studies and in electric drives (the so-called instantaneous reactive power).
Abstract: This letter provides a unified exposition of various definitions of reactive (or inactive) power. In particular, it presents a comparative frequency-domain analysis of definitions used in power system studies and in electric drives (the so-called instantaneous reactive power). Concepts are illustrated on a common trample.
Journal Article•
TL;DR: In this article, the application of optimal reactive power flow (ORPF) to the New Brunswick (NB) power system is presented, and the potential benefits and real-time implementation problems of ORPF are discussed.
Abstract: The application of optimal reactive power flow (ORPF) to the New Brunswick (NB) power system is presented. The potential benefits and the real-time implementation problems of ORPF are discussed. Some important issues of real-time implementation on ORPF, such as frequency of running, the number of activated control variables, and the order of adjustment of different controls, are discussed. The application of ORPF on the NB power network has shown two major benefits: (1) an improvement in the voltage profile and voltage stability, and (2) a saving in active power loss. The improvement in the voltage profile can cause fewer violations and a more stable system from the voltage point of view. A reduction in active power loss gained from ORPF can save a significant amount of money. The total ideal savings for the year 1997 predicted in the study was in excess of $900000, however, only 10 to 30% of this amount is realistically obtainable due to operational and other constraints. These savings can be gained simultaneously with the improvement of the voltage profiles.
TL;DR: A brief history of the development of superconducting motors with emphasis on the use of high temperature superconductors is given in this article, where the rotor for the 1000hp HTS motor was designed to accommodate other coils and can provide a test bed for wire developed in the future.
Abstract: The article gives a brief history of the development of superconducting motors with emphasis on the use of high temperature superconductors. At present, effort is directed toward the demonstration of a 1000 hp HTS motor, the test of which will mark another significant milestone in HTS motor development. For the first time, a closed-loop refrigeration system will be used to maintain an operating temperature near 30 K for the HTS field winding. Following the conclusion of the 1000 hp HTS motor project, a 5000 hp HTS motor will be constructed and tested to demonstrate its economical viability. The progress in developing HTS motors to date is shown. The rotor for the 1000 hp motor was designed to accommodate other coils and can provide a test bed for wire developed in the future.
TL;DR: In this article, the authors describe an approach to a representation of transient behavior due to switching off complex nonlinear circuits, using the widely known Jiles model (JM) implemented into the Alternative-Transient Program (ATP).
Abstract: The letter describes an approach to a representation of transient behavior due to switching off complex nonlinear circuits. For this purpose the widely known Jiles model (JM) was implemented into the Alternative-Transient-Program (ATP). Calculations have been made on simplified transformer single-phase and three-phase circuits.