scispace - formally typeset

Showing papers in "IEEE Computer Applications in Power in 1997"


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TL;DR: In this paper, a short circuit on a 345-kV line in Wyoming, USA, started a chain of events leading to a breakup of the Western North American power system and five islands formed with controlled and uncontrolled load shedding, uncontrolled generation tripping, and with a blackout in Southern Idaho.
Abstract: On July 2, 1996, a short circuit on a 345-kV line in Wyoming, USA, started a chain of events leading to a breakup of the Western North American power system. Five islands formed with controlled and uncontrolled load shedding, uncontrolled generation tripping, and with a blackout in Southern Idaho. The Western power system is operated by power companies belonging to the Western Systems Coordinating Council, which had a peak 1996 summer load of around 118,000 MW. July 2 was the third and, until the August 10 large-scale power failure, the most disruptive of a series of Western system breakups. The first was caused by the January 17, 1994, Northridge California earthquake. The second breakup occurred in the early morning hours of December 14, 1994, and, like July 2, originated in Southern Idaho and Wyoming. Modern computer and communication technologies greatly facilitated dissemination of information, analysis, report writing and event simulation for the July 2 cascading outage. This article analyzes the breakup, relying heavily on recordings from portable power system monitors which are installed at key locations and serve as primary components of a wide-area measurement system project.

168 citations


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TL;DR: The authors detail how the Dynamic Information Technology Package (DITPak) has evolved and how it now includes virtual instrumentation using LabVIEW software, modular and readily networked measurement hardware, streamlined analysis software in a MATLAB working environment and optional use of familiar workstation tools for display and report generation.
Abstract: The authors describe how the Bonneville Power Authority (USA) began to develop integrated monitoring and analysis tools to meet the need for accurate and coordinated dynamic power system information in 1990. They detail how the Dynamic Information Technology Package (DITPak) has evolved and how it now includes virtual instrumentation using LabVIEW software, modular and readily networked measurement hardware, streamlined analysis software in a MATLAB working environment and optional use of familiar workstation tools for display and report generation.

101 citations


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TL;DR: In this paper, the authors present recent developments in providing tools for the diagnosis of faults or incipient faults in electric motor drives, including: sensorless torque measurement; direct detection of turn-to-turn short circuits; detection of cracked or broken rotor bars; and detection of bearing deterioration.
Abstract: Early detection of abnormalities in electric motors helps to avoid expensive failures. Motor current signature analysis (MCSA) implemented in a computer-based motor monitor can contribute to such condition-based maintenance functions. Such a system may also detect an abnormality in the process as well as the motor. Extensive online monitoring of the motors can lead to greater plant availability, extended plant life, higher quality product, and smoother plant operation. With advances in digital technology over the last several years, adequate data processing capability is now available on cost-effective, microprocessor-based, protective-relay platforms to monitor motors for a variety of abnormalities in addition to the normal protection functions. Such multifunction monitors, are displacing the multiplicity of electromechanical devices commonly applied for many years. Following some background information on motor monitoring, this article features recent developments in providing tools for the diagnosis of faults or incipient faults in electric motor drives, including: sensorless torque measurement; direct detection of turn-to-turn short circuits; detection of cracked or broken rotor bars; and detection of bearing deterioration.

86 citations


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86 citations


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TL;DR: In this paper, the Rogowski coil is used for current measurement in the context of relay protection and current measuring systems, where it is shown that it can be used to accurately replicate events.
Abstract: Microprocessor-based technology has been accepted today in virtually all areas of electrical engineering, including power. Input signals that accurately replicate events are critical for the proper operation of microprocessor-based equipment. Therefore, current sensors are an integral element of relay protection and current measuring systems. Current transformers (CTs) have been used exclusively for protection and measurement applications in part because of their ability to produce the high power output needed by electromechanical equipment. The introduction of microprocessor-based equipment has made the high-power output of CTs unnecessary and made the use of other measurement techniques possible. One such measuring device that does not produce high-power output but offers many advantages over CTs is the Rogowski coil. This article describes Rogowski coil operational characteristics and it applications for current measurements.

72 citations


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TL;DR: In this article, the authors define the framework and motivation for the development of a multilayered protection and control scheme that starts with local measurement devices and integrates higher-level control schemes into an overall control strategy.
Abstract: As open transmission access is becoming a reality, a major concern of electric power utilities is to maintain the reliability of the grid. Increased power transfers raise concerns about steady-state overloads, increased risks of voltage collapse and potential stability problems. Strengthening the protection and control strategies is what utilities must do to prevent a local problem from spreading to other parts of the grid. This article defines the framework and motivation for the development of a multilayered protection and control scheme that starts with local measurement devices and integrates higher-level control schemes into an overall control strategy.

67 citations


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B. Ingelsson, P.-O. Lindstrom, D. Karlsson, G. Runvik, J.-O. Sjodin1 
TL;DR: In this article, a wide-area protection system against long-term voltage collapse was designed, implemented, tested, modified, and commissioned, which is based on the present SCADA system in southern Sweden, complemented with input signals and equipment to execute action orders from the protection system.
Abstract: A wide-area protection system against long-term voltage collapse was designed, implemented, tested, modified, and commissioned. The system is based on the present SCADA system in southern Sweden, which has been complemented with input signals and equipment to execute action orders from the protection system. Bus voltages from the transmission system, reactive power output from generators connected to the transmission system, and current limiter information from main generators were used as input signals to the wide-area protection system. Actions from the protection system are shunt reactor disconnection, shunt capacitor connection, start of gas turbines, emergency power request from the HVDC connection to Germany, low priority load disconnection, and finally shedding of high priority load.

54 citations


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TL;DR: A new concept for expanding the scope of power system security functions in an EMS control center is presented, an approach which combines automatic learning applied to dynamic security analysis and a changeover of the conventional operator training simulator into a dynamic OTS.
Abstract: This article presents a new concept for expanding the scope of power system security functions in an EMS control center, an approach which combines automatic learning applied to dynamic security analysis and a changeover of the conventional operator training simulator (OTS) into a dynamic OTS. Automatic learning is shown to be suitable for power system dynamic security analysis, provided training-set generation is effective and the output adds value to the decision-making process.

52 citations


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TL;DR: In this paper, a coordinated power system defense plan is proposed to prevent large regions of France or the entire power network from suffering blackouts and to accelerate restoration, with the goal of preventing the entire network from being affected.
Abstract: The electricity generation, transmission and distribution systems in major countries are planned, operated and protected so as to withstand any hazards that are likely to most affect them (short circuits, tripping of a line or generating set), without damage to customers. However, compliance with normal dependability and security practices does not result in a fully safe system protected against major collapses. These may result from the accidental coincidence of more fragile operating conditions and serious damage or from many successive adverse hazards far beyond those against which precautions are generally taken. This paper describes a coordinated power system defense plan, the goal of which is to prevent large regions of France or the entire power network from suffering blackouts and to accelerate restoration.

42 citations


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TL;DR: PowerWorld, a comprehensive power system simulation package, is designed for the many new players in the power industry who will never operate an actual system but who must have a basic understanding of its operations.
Abstract: All players in the US electricity industry must understand how specific generation decisions, wheeling arrangements, and legislative initiatives affect system operations. This article features PowerWorld, a comprehensive power system simulation package developed to help meet this need. The package is designed for the many new players in the power industry who will never operate an actual system but who must have a basic understanding of its operations. The package, which runs in the Microsoft Windows environment, is user friendly, interactive, and menu driven. It effectively uses visualization techniques to present the basics of power system operations and control simply, yet also with a level of detail to accurately model large-scale systems realistically and with the appropriate level of fidelity. The package has been demonstrated to policy makers, legislative analysts, small and large utilities, and regulatory decision makers both nationally and internationally. It has been found to be a very effective tool for communicating the many technical and economic impacts of third-party access.

38 citations


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TL;DR: A brief introduction to fractals is provided and some fractal patterns produced by Newton-Raphson load-flow calculations for a small power system are presented.
Abstract: Fractal images have been discovered in many areas of science and engineering in the past two decades, so it is not surprising that they have also appeared in power system literature. This article provides a brief introduction to fractals and presents some fractal patterns produced by Newton-Raphson load-flow calculations for a small power system. If we imagine performing load-flow calculations from a dense grid of initial conditions, the region of initial conditions that converge to a particular equilibrium point using the Newton-Raphson method is seen to have a fractal boundary.

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TL;DR: In this paper, the authors describe how Garland Power and Light (USA), a medium-sized municipal electric utility serving a population of about 200,000 and a customer base of about 70,000, has chosen to take a proactive path and is equipping its substations with distribution automation tools for power quality monitoring and better control of restoration techniques during outages.
Abstract: The impending regulatory issues that pave the way for a more competitive electric utility market have prompted most utilities to search for new or improved ways of ensuring that their services are reliable and cost effective. This paper describes how Garland Power and Light (USA), a medium-sized municipal electric utility serving a population of about 200,000 and a customer base of about 70,000, has chosen to take a proactive path and is equipping its substations with distribution automation tools for power quality monitoring and better control of restoration techniques during outages.

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TL;DR: In this article, the computer modeling of power system electromagnetic transients is discussed by the author, where three three-phase circuits adjacent to each other are modeled as nine coupled phases and current interruption takes place at current zero, while the other two phases would interrupt later at instants whenever their current passes through zero.
Abstract: With few exceptions, power system electromagnetic transients must be studied on a three-phase basis rather than on a positive sequence single-phase basis. For example, the three-phase opening of a circuit breaker is no longer a symmetric event in the ms range. Current interruption takes place at current zero, and one phase would open first at its current zero, while the other two phases would interrupt later at instants whenever their current passes through zero. Electromagnetic transients programs are usually not limited to three phases, but can generally handle any number of phases. Three three-phase circuits adjacent to each other would simply be modelled as nine coupled phases. Here, the computer modeling of power system electromagnetic transients is discussed by the author.

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TL;DR: In this article, a more practical approach based on automatic cable routing on the terrain of a given area rather than on the layout of roads is proposed, where the automatic distribution network router (DNR) finds the least-cost path (not merely the shortest one) connecting two nodes.
Abstract: Specifying the actual layout of all overhead power lines and underground power cables is one of the key tasks to be carried out in the design of electrical distribution networks. Voltage drop and other network calculations can be performed only after the length of each cable segment is determined. Although automatic cable routers are currently available, they are mainly for formally planned urban areas. These routers are not always appropriate for use in designing rural distribution networks, because they fail to account for some of the special circumstances found in rural areas. A more practical approach bases automatic cable routing on the terrain of a given area rather than on the layout of roads. The automatic distribution network router (DNR) finds the least-cost path (not merely the shortest one) connecting two nodes. This article briefly discusses methods currently used to determine cable routes for distribution networks, the unsuitability of these methods for routing cables in rural and informal urban areas, the proposed approach that relies on dividing the terrain into cost regions, and the benefits gained in its application. Emphasis is on the practical application of the new approach.

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TL;DR: A new system identification software program, SYSID, is developed that allows for the computation of equivalent linear models, suitable for control design applications, from time domain simulation data.
Abstract: Traditionally, the linear analysis of a power system is performed by first computing a state space model, followed by the application of a suitable analysis method. However, the applicability of this approach is restricted by several practical limitations: typical power systems are represented by very large state matrices that require specialized large-scale eigen analysis programs; the program where the power system models reside does not include linearization capabilities; only time domain data is available. This article illustrates the applicability of a new system identification software program, SYSID, developed to circumvent these limitations. The program incorporates several identification techniques that allow for the computation of equivalent linear models, suitable for control design applications, from time domain simulation data. The program has been used to calculate equivalent models from simulations performed with standard stability programs, as well as from the Electromagnetic Transient Program (EMTP) simulations of detailed three-phase power systems. The equivalent systems are small and retain the modal characteristics of the original system. The identification techniques are based on various algorithms including Prony's method, transfer function fitting, and Hankel matrices. In addition to the identification algorithms, the program also includes signal processing, plotting, modal analysis functions, and basic control design capabilities to assess closed loop system performance.

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TL;DR: The authors describe how AI-related application areas, such as expert systems, fuzzy logic, neural networks and genetic algorithms, can all be applied in such intelligent systems.
Abstract: The authors describe how the use of intelligent systems (IS) is an opportunity to add new dimensions to the field of computer applications in power systems. A number of practical power system problems require logic reasoning, heuristic search, perception, and/or the ability to handle uncertainties; IS tools can be part of their solution. The authors describe how AI-related application areas, such as expert systems, fuzzy logic, neural networks and genetic algorithms, can all be applied in such intelligent systems.

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TL;DR: This article describes courses and personal computer (PC) based facilities that are available at the University of Saskatchewan, Canada, with a focus on research and teaching in the area of power system protection.
Abstract: It is a general perception that power subjects are concerned with the study of high-voltage, high-current components, such as large machines and high voltage transmission lines. But that is a narrow-minded view. The subject of modern protection, for example, is interdisciplinary by nature. This article describes courses and personal computer (PC) based facilities that are available at the University of Saskatchewan, Canada, with a focus on research and teaching in the area of power system protection. Experience with the use of the laboratory facilities is encouraging and shows enhancements to the quality of teaching and research.

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TL;DR: In this paper, the authors analyze the implications of this massive change from the perspective of various participants and show how their roles are affected by the changes, and how to take advantage of the advances in technology in designing and implementing the new applications and the systems that need to go with them.
Abstract: With the Federal Energy Regulatory Commission (FERC) Order 888/889 mandating open access of the nation's transmission network, the US electric utility industry begins its most significant transformation. Once highly regulated and organized into vertically integrated entities, the industry today is being restructured into a competitive arena made up of veterans as well as new players from other industries. All participants are facilitating change through the establishment of new business processes and information flow and in the development of the functions that will support a deregulated marketplace. They must take advantage of the advances in technology in designing and implementing the new applications and the systems that need to go with them. This article analyzes the implications of this massive change from the perspective of the various participants and shows how their roles are affected by the changes.

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TL;DR: The authors detail how their representations use a scale of carefully chosen colors based on characteristics of human visual perception and mental models of color usage in the power industry to be effective for large-scale power system simulation.
Abstract: To be effective for large-scale power system simulation, the bus voltage representation has several issues to be resolved. The selected method must be able to handle a large amount of information effectively. For that purpose, each element must be simple and small, easy to identify and to discern in any environment. This is the principal objective of the authors' research, and of this article. They detail how their representations use a scale of carefully chosen colors based on characteristics of human visual perception and mental models of color usage in the power industry.

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TL;DR: How DRDs and monitoring systems need triggering algorithms and settings that dependably and securely detect unusual events in the presence of normal power system events is described.
Abstract: Dynamics recording devices (DRDs) that monitor and record the transient or dynamic response of power systems are installed across power systems. DRDs that have been installed in the last decade have increasingly used digital computer implementation-these include digital relays, digital fault recorders, integrated electronic controls for substation automation and many digitally implemented controls such as excitation system controls and stabilizers. Here, the authors describe how DRDs and monitoring systems need triggering algorithms and settings that dependably and securely detect unusual events in the presence of normal power system events.

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TL;DR: In this article, the authors describe how the Korea Electric Power Corporation (KEPCO) has successfully completed twenty-four overhead transmission line upgrade projects in Korea from 1994 to 1997 for a total cost of US$54.6 million.
Abstract: The authors describe how the Korea Electric Power Corporation (KEPCO) has successfully completed twenty-four overhead transmission line upgrade projects in Korea from 1994 to 1997 for a total cost of US$54.6 million. Upgrades to existing transmission lines were accomplished by replacing existing conductors with high ampacity conductors using existing towers and rights-of-way. Transmission line capacity is doubled with these high-capacity conductors. Planning studies and construction of the upgrade projects were facilitated by using LINEAMPS transmission line ampacity software.

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TL;DR: In this article, the authors present guidelines for developing electrical monitoring projects, since any choice will depend on many specific variables; however, the most important points to take into account are as follows.
Abstract: Modern industrial production processes have always been supervised and/or controlled in many different ways. The evolution of control methods was motivated by technological advances and by the requirements of the processes themselves. Many processes are supervised and controlled in an automated environment due to improvements in electronics and computer science. In the electric power industry, there is a strong need to control and supervise the production and distribution of energy, so as to avoid possible power failures. The supply of energy must always be guaranteed (even in adverse conditions), and control involves different systems (high and low voltage lines, compensation, and filtering systems, etc.), so operators require quick and reliable access to meaningful information. The option to interfere in some processes must be provided. All these goals are accomplished using an appropriate control architecture, communication networks, and symbolic representation of electrical network systems. Operator efficiency will be assured if these requirements are met. There are no unique guidelines for developing electrical monitoring projects, since any choice will depend on many specific variables; however, the most important points to take into account are as follows.

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TL;DR: The book presents a systematic approach to the spatial load forecasting problem, that is, the problem of where load growth is expected to occur, and should serve as a valuable single-volume reference for those interested in load forecasting for distribution planning.
Abstract: H. Lee Willis has written a useful book that should be intelligible to a wide range of utility practitioners, from distribution planners with engineering backgrounds to load forecasters with economics and statistics backgrounds. The book presents a systematic approach to the spatial load forecasting problem, that is, the problem of where load growth is expected to occur. This problem is distinguished early on from the system load forecasting problem, the more familiar load forecasting exercise that deals with how much load growth is expected to occur. As evidenced by the bibliographic citations throughout the book, which refer almost exclusively to articles in professional journals and magazines, or proceedings from industry conferences, the book is unique in its focus on the spatial element of load forecasting and thus should serve as a valuable single-volume reference for those interested in load forecasting for distribution planning. The organization of the book is logical and progresses from a discussion of fundamentals of load analysis, such as coincidence and load shape, to a detailed case study of a spatial forecasting problem. Part of the discussion in the early chapters is devoted to highlighting important differences between load at the distribution (or small area) level and the system level. These differences include the dominating influence of coincidence on the behavior of load at the distribution level as well as its characteristic “Scurve” growth path. Two of the more interesting chapters in the book cover forecasting methods: the first, trending methods, and the second, simulation methods. While most practitioners will be familiar with the methods discussed in these chapters, the author provides a useful comparative study that will be of value in many forecasting situations. The core of the book consists of three chapters, Chapter 8 through Chapter 10, that describe the making of a spatial load forecast for distribution planning. These chapters offer step-by-step instruction. Chapter 8, which describes a manual forecast, may be the most useful of the three. It gives a good sense of precisely why one would want to do a distribution forecast, and a careful reading will yield benefits in the last few chapters. Lurking in just about every chapter (but fully explored in Chapter 10) is the notion that the spatial forecast

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TL;DR: Two automatic relay testing systems that minimize power system protection relay maintenance times and costs and improve the quality and reliability of relay management are introduced.
Abstract: With the appearance on the market of electronic test equipment that is controlled by software from personal computers, automation of classical test methods has been achieved and new methods have been developed. For engineers and technicians in charge of performing integrity and application tests, steady-state and dynamic tests can provide helpful information used in design, commissioning and preventive and corrective maintenance. These test methods result in savings of time and the cost involved in these tasks. Since 1990, the Spanish electric utility, Iberdrola, and the Electrical Department of the University of the Basque Country have been developing tools to: automate protective relay testing; analyze the location and characteristics of faults in the power network on the basis of oscillographic records; and simulate real or hypothetical fault conditions on a protective relay in order to monitor its behavior. Two automatic relay testing systems and experience of their use are introduced in this article. Particular testing protocols of different relays are incorporated and all useful features available to increase the automation grade are considered. Both systems minimize power system protection relay maintenance times and costs and improve the quality and reliability of relay management.

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TL;DR: IFL as mentioned in this paper is a PC/Windows-based operator's tool that uses two-ended loop fault analysis to identify fault types and location, and it is innovative in its integration of mature, low cost, and reliable instrumentation, combined with advanced applied mathematics to achieve a missioncritical system for electric system maintenance and operation.
Abstract: When faults occur on major transmission lines, the bulk power system is immediately exposed to potentially costly outages. During peak loading conditions, when line availability is most critical, a lengthy outage can be detrimental to system operations. In an age of open access and retail wheeling, power exchanges are bound by contract, and any unnecessary delay of energy restoration compromises a utility's competitive position. It is necessary for protection and operation personnel to locate the fault as accurately and as expeditiously as possible. Within large utility systems, major transmission lines are located in remote or inaccessible areas, which makes fault finding difficult. The combination of using a two-ended algorithm along with the advent of improved communication technology, mathematical techniques, and PC applications made possible the development of an automatic fault location system. IFL is a PC/Windows-based operator's tool that uses two-ended loop fault analysis to identify fault types and location. The system is innovative in its integration of mature, low cost, and reliable instrumentation, combined with advanced applied mathematics to achieve a mission-critical system for electric system maintenance and operation.

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TL;DR: In this article, the authors describe a new generation of measurement systems which makes use of remote fiber-optic sensors, centralized control computers and expert systems, which rely on some physical properties of optical fibers and on sophisticated data analysis.
Abstract: The integration of power network measurement systems based on optical fibers used as sensors is now possible, and computers play an important role in this integration. These systems rely on some physical properties of optical fibers and on sophisticated data analysis. They have the advantage of electrical noise immunity and are highly reliable. Here, the authors describe a new generation of measurement systems which makes use of remote fiber-optic sensors, centralized control computers and expert systems.

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TL;DR: This article describes one solution that has been developed to address the problem of data expression with emphasis on some graphical aids that provide visual verification of the reasonableness of the data as entered.
Abstract: Nearly all of the human effort in computing the parameters of overhead power transmission lines lies in the collection and entry of data. One must assemble data for conductors, tower designs and rights of way and then place the conductors on the towers and the towers in rights of way in a way that will result in the correct computation of self- and mutual-series impedances and shunt admittances. One can reasonably expect to find libraries of conductor data, or at least they are available in published references, but all the other data are specific to a given utility and must be developed and entered by the user. This article describes one solution that has been developed to address this problem of data expression with emphasis on some graphical aids that provide visual verification of the reasonableness of the data as entered.

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TL;DR: The author describes the World Wide Web, hypermedia documentation, and Web resources for the power engineer, and how this information was obtained is illustrated to serve as an example for the reader.
Abstract: It seems that whenever you pick up a newspaper or turn on the evening news there is something new about the Internet and the World-Wide Web (WWW or Web). When you attend a technical conference, speakers encourage you to look at their home pages for more information. Sales representatives provide you with a URL for more detailed technical specifications on their products. For some, the idea of surfing the net, FTPing files, and chatting on a newsgroup is second nature. To others it's a foreign language. However, this is a foreign language in which all power engineers should be proficient, because it is the language of the future. The author reviews some history, defines some terms, and discusses how to use the Internet. The author then describes the World Wide Web, hypermedia documentation, and Web resources for the power engineer. All of the information for this article was obtained using the Internet and the Web. How this information was obtained is illustrated to serve as an example for the reader.

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TL;DR: In this paper, the authors describe how ISO 9000 software processes were implemented at the Cadence India Engineering Center and define the benefits gained by the company from the perspectives of its management, employees and customers.
Abstract: All over the world, electrotechnical companies are facing increasing competition in the marketplace. The key to success is higher quality products and services, and many companies are adopting the ISO 9000 series of international quality standards. In the electronics and power industries, suppliers such as Philips, IBM, Siemens, ABB and HP have already implemented the standards in most of their development sites. Recently, the Electric Power Research Institute (EPRI) notified its software development contractors that ISO 9000 certification will provide them with a substantial competitive edge in winning new contracts. This article describes how ISO 9000 software processes were implemented at the Cadence India Engineering Center and defines the benefits gained by the company from the perspectives of its management, employees and customers. Benefits of well-defined processes in term of quality and cycle-time are very apparent and process maturity is a key to achieving positive cultural change.

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A. Apostolov1, S. Monnier, R. Taylor
TL;DR: In this paper, the authors describe how cost savings in installation, maintenance, and operations are possible because of the integration of microprocessor-based protective relays into such substations and power systems.
Abstract: The electric utility industry is going through a period of significant changes in technology and business environment. Microprocessor-based protection, control and metering devices have become the standard in substations and power plants. Here, the authors describe how cost savings in installation, maintenance, and operations are possible because of the integration of microprocessor-based protective relays into such substations and power systems.