Showing papers in "IEEE Computer Applications in Power in 2000"

Dynamic thermal ratings realize circuit load limits

Abstract: As economic pressure builds to fully utilize the capacity of existing power equipment, dynamic rating systems allow for informed decisions about circuit load limits. Dynamic thermal ratings offer a way to increase capacity under most weather- and load conditions while reducing the risk of failure under unfavorable conditions. EPRl's Dynamic Thermal Circuit Rating (DTCR) system makes thermal information readily available and provides a solid basis for higher equipment utilization. DTCR calculates dynamic thermal ratings (real-time ampacities) of power equipment based on actual load and weather conditions that are generally accessed through the utility's SCADA/EMS system. Given series or parallel combinations of equipment, the software determines dynamic circuit ratings by evaluating all equipment ratings on a circuit and finding the most limiting ampacity for each rating scenario. Dynamic ratings offer two key benefits over traditional static ratings: (1) higher loading of equipment is usually possible using actual measured load and weather parameters; traditional static ratings are overly conservative, since they are based on worst-case weather and load assumptions; and (2) a better understanding of equipment thermal response is achieved. This results in increased reliability.

Neural net and expert system diagnose transformer faults

Abstract: Dissolved gas-in-oil analysis (DGA) is a common practice in transformer incipient fault diagnosis. The analysis techniques include the conventional key gas method, ratio methods, and artificial intelligence methods. Application of artificial intelligence (Al) techniques have shown very promising results. The methods include fuzzy logic, expert systems (EPS), evolutionary algorithms (EA), and artificial neural networks (ANN). A transformer incipient fault diagnosis system (ANNEPS) was developed over a period of 5 years at Virginia Tech, collaborating with Doble Engineering Company. The system can detect thermal faults (distinguishing overheating of oil from that of cellulose and between four overheating stages and overheating of oil), low-energy discharge (partial discharge), high-energy discharge (arcing), and cellulose degradation.

Managing risk in the new power business

Abstract: Managing risk is central to engineering, to business, and, in fact, to most human endeavors, and computer analysis is central to managing risk. This article gives a broad exposition of risk in the competitive and privatized electric power business. Contrary to much that is being written today, the emphasis of this article is on nonfinancial risks, hazards that are neither measured nor hedged using tools of financial markets. The focus is on practical methods for modeling and managing risk, and real examples are provided.

Control centers evolve with agent technology

Abstract: Energy management system (EMS) architectures are deeply influenced by power system and information system scenarios. The computer industry has been evolving continuously, and the power industry, which remained relatively stable for decades, is now undergoing revolutionary changes that require the special attention of EMS developers. The introduction of new players, the decentralization of production and processing of information, and competition will change the way control centers operate and, consequently, their architecture. Distinct areas of computer science have suggested many different approaches to tackle the problems that arise in the new decentralized scenario. Of particular interest, agent technology, proposed in the context of distributed artificial intelligence, is a very promising approach to support the construction of a new generation of EMS in an open environment.

Standards-based approach integrates utility applications

Abstract: Today's utility business environment of deregulation and more volatile energy markets has forced utilities to operate more efficiently and become more flexible. However, utilities cannot adapt to changing business conditions without having a flexible information technology (IT) infrastructure as well as information about and complete control of operational systems. While traditionally the business and power system control functions in an electric utility were run more or less separate and apart from each other, such isolation inhibits efficient operation and inhibits high-level, profit-oriented analysis from occurring. What is needed is a framework that enables data to be quickly shared, coalesced, and transformed into usable information. This framework should be robust enough so that, as new situations arise, information can be exchanged and analyzed in ways not previously anticipated. This article discusses utility application and data integration issues and related standards activities. A summary of work going on within the Electric Power Research Institute's (EPRI) Control Center Application Program Interface (CCAPT) task force, the International Electrotechnical Commission (IEC) working groups 13 and 14, and the Utility Domain task force in the Open Management Group (OMG) is provided. EPRI's Common Information Model (CIM) and Message Bus are described with emphasis on how they can be used to create a powerful and flexible enterprise architecture.

Object-oriented design for power system applications

Abstract: A sound design method is based upon a sound theoretical foundation, yet it offers degrees of freedom for artistic innovation. In the object oriented paradigm, the world is viewed as a collection of objects interacting with each other to achieve a meaningful behavior. The design perspective provided in this article can be used for many applications, such as power system state estimation and optimal power flow (OPF), and the sparse matrix class can be developed further to include eigenvalue analysis. As such, the architecture presented in this article is scalable.

Advanced dispatcher training simulator

Abstract: This article analyzes the modeling and describes the algorithmic breakthroughs and the use of parallel processing in power system dispatcher training simulation. The first industrial version of the FAST-DTS simulator (running a 400 node, 80 generator power system), with its advanced instructor and operator stations, is described and illustrated with various training scenarios. Principles used for the configuration and the compatibility with EUROSTAC (reference software dedicated to the dynamic simulation of power systems in the field of transient and long-term stability) and further developments are also discussed.

Educational toolbox for power system analysis

Abstract: Power system simulation involves a wide range of timeframes, starting at microseconds when simulating fast electromagnetic transients and extending to several years in system planning studies. The same system may have to be modeled and solved in many different ways, depending upon the studied event of interest. It has been desirable to have a single software platform from which several power system analysis functions can be easily activated for the same power system. The network under study may go through changes due to switching events, outages of equipment, generators, or loads. Such changes should be recorded only once and recognized by all applications running under this platform. Each application should have easy access to the results produced by any other application. This allows modular development, updating, or replacement of various applications independent of each other. Power Education Toolbox (PET) is such a software package and has been under development at Texas A&M University for several years. The GUI of PET allows users to create one-line diagrams of systems, specify components and simulation parameters, and view output.

Automated solutions for distribution feeders

Abstract: As computers and other electronic equipment become the mainstay of today's businesses, customer awareness and intolerance for power system outages continues to heighten. For these customers, it is important that utilities be able to offer complete solutions to meet their needs. Depending on the customer load requirements, standby generation, uninterruptible power supply, or automatic restoration are possible solutions to improve the system reliability. In addition, utilities are becoming increasingly automated to keep up with the demands of the new business environments. As newly reregulated distribution companies emerge, it is likely that reliability indexes will be one of the key factors for regulators to examine to determine the overall performance of the distribution company. Thus, drivers for distribution automation include: remote control and restoration; targeted regions or customers for improved reliability and operation; performance based rates (PBR); and safety issues for circuit isolation. Whatever the driver for feeder automation, several key issues must be addressed: what automation scheme is required? How are communications implemented? This article addresses these issues with example solutions for overhead feeder automation.

Imaging radar maps underground objects in 3-D

Abstract: City streets cover a complex array of underground electric, gas, and communication lines. Effective maintenance, expansion, and new installation of these networks require accurate information regarding the location of the conduits, cables, and other structures that lie beneath the surface. Underground maps, if they exist, are often inaccurate, incomplete, or out of date, and attempts to find underground lines or obstacles using metal locators often prove disappointing. To help companies create accurate maps of subsurface networks, researchers have developed a new ground-penetrating imaging radar (GPIR) system that creates sharp, three-dimensional (3-D) images of underground lines and objects. Schlumberger Corporation, in conjunction with the Electric Power Research Institute (EPRI) and the Gas Research Institute, has developed a GPIR system that detects, locates, and produces 3D maps of underground features. The new underground imaging system holds the potential to reduce utility operating and maintenance costs by avoiding unneeded excavation and by reducing incidences of costly damage such as ruptured gas lines. Field demonstrations in New York City, San Diego, and other utility locations have proven the ability of the new mapping system to create accurate images of objects in crowded urban areas at depths as great as 10 ft (3 m).

Tapping protective relays for power quality information

Abstract: Protective relays are vital components of power systems. They are deployed on every piece of major equipment and are attached to every circuit breaker in the system. As microprocessor technology continues to expand, microprocessor-based protective relays will enjoy enhanced functionality. Load profiling, fault oscillographic waveform capture, and metering are some of the enhanced functionality available in microprocessor-based protective relays. This article shows how existing signal processing capabilities of protective relays can be used to intelligently monitor power quality (PQ). The definition of power quality, the available functions, and their application to utilities are examined. In particular, it is noted that those PQ events that industrial account managers are interested in (voltage sags, swells, interruptions) and additional events PQ engineers need (waveform capture, harmonics) can be gathered by protective relays. The article concludes with some field results from a microprocessor-based protection unit. While this article discusses the integration of power quality monitoring into protective relaying specifically, PQ monitoring is also integrated into other intelligent electronic devices (IEDs) that have access to the system voltages and currents such as switch controllers and meters.

Digital testing of high-voltage circuit breakers

Abstract: The functionality of high-voltage circuit breakers is tested in high-power laboratories. Due to the necessary power and the physical size of the equipment, testing is rather expensive and time consuming. The steps followed so far by the authors in order to enable the digital testing of HV circuit breakers are described in this paper. At the end of the article, examples of digital testing are also presented.

Using outage data to improve reliability

Abstract: This paper illustrates how an electric utility can use a sophisticated outage management system (OMS) to improve power system performance by: establishing accurate failure rates and outage times; identifying specific areas that contribute to poor system reliability indexes; using actual data to improve the accuracy of predictive reliability studies; and establishing system performance without the use of costly monitoring systems.

Object-oriented methods drive protective relay system

Abstract: China is a developing country, and shortages in electrical power supply exist in most provincial power systems. Stability margins are always very limited, which requires operators to run the system carefully. With each change in either the power system configuration or operating conditions, a series of actions must be taken to guarantee the safety of the power system. The actions adopted for the protective relays include arranging protective devices appropriately and setting relays at their appropriate values for all elements involved. In addition, as power systems are developing very fast in China, the number of skilled operators available is far less than required. Expert systems are urgently needed. This article describes the use of object-oriented (OO) methods to develop expert systems and, in particular, features the object-oriented expert system for the power system protective relay operation and management (OOPRES). The article covers knowledge acquisition and representation, knowledge management, and inference engine.

Real-time supervision for STATCOM installations

Abstract: This article discusses the implementation of an operational monitoring and fault diagnosis system (OMFDS) for a /spl plusmn/20 MVAr voltage-sourced STATCOM based on gate-turn-off thyristor (GTO). It well fulfills the purpose of real-time supervision, intelligent alarm handling, post-fault system analysis and gratifying man-machine interaction. The proposed system, with minor modification if needed, can also be applicable to other FACTS controllers or other power electronic devices.

Automatic test system advances transformer protection

Abstract: In the last 10 years, computers have become part of every aspect of power system protection engineering Multifunctional microprocessor-based relays with increasing complexity require the development and application of sophisticated computer software for the analysis, setting coordination, data acquisition and testing of such intelligent electronic devices (IEDs) Their functionality is modular and, at the same time, very specialized, as required by the protected substation or power system equipment Conventional methods and test devices used for the testing of electromechanical protective relays are no longer adequate for the testing of advanced microprocessor relays

Digital relay reports verify power system models

Abstract: Protective relays continuously monitor the power system to detect abnormal conditions, such as short circuits, that could be damaging to equipment or to the integrity of the system as a whole. They initiate corrective actions (often tripping circuit breakers) to remove the smallest possible portion of the electric system to isolate faulted equipment and allow the remaining part of the system to continue to generate and deliver power. The relay engineer uses "fault studies", or models of the power system operating under normal and short-circuit conditions, to determine what parameters should be measured and what relay settings should be used to discriminate reliably between acceptable and unacceptable system conditions. Like all models, the usefulness of fault study models depends on their validity and accuracy. This article encourages digital relay users to look more closely at their records of disturbances. In addition to the normal use of checking relay performance, these records can also be used to check the accuracy of the power system model.

Operator training tools for the competitive market

Abstract: The power industry is being changed following the deregulation of the electricity generation and power system markets. Competition between numerous utilities leads to the necessity to optimize the operation of power plants and networks, i.e., to decrease the operation costs and to increase the reliability of the equipment. A new generation of simulation and training software workshops is necessary to keep abreast of this evolution. CORYS T.E.S.S. and Tractebel Energy Engineering responded to these new challenges by developing the ALICES software workshop. This article shows that modeling and simulation can contribute to providing the answers to the industry's new challenges. The article begins with an economical justification for simulation and training, focuses on the new generation of simulation software tools, and ends with several case studies to show how the tools are being used in the field.

End-to-end relay tests use secondary injection

Abstract: The advances in relay test sets, personal computers (PC), and the availability of satellite clocks have taken fault-simulated, end-to-end relay testing by secondary injection to new heights. This creative approach to relay testing allows relay technicians and engineers to comprehensively check line relays and evaluate their dynamic response to faults without staging actual faults on energized transmission lines. The testing technique offers flexibility, speed, and accuracy in testing line relays.

Random adaptive optimizer restores distribution service

Abstract: Power network faults may lead to blackouts in some areas. Dispatchers should accurately diagnose faulted elements as soon as possible and restore those areas to their normal state. The restoration of the blackout area in a distribution network is a complex nonlinear combinatorial optimization problem, which is to restore as much of the blacked out area as possible and not to lead to overload in the normal area. In view of the limitation of the conventional expert system (ES) based on rules for restoring a blacked out area, a new random adaptive optimizing method based on a genetic algorithm (GA) is applied to the restoration system of the distribution network.

Reliability and tools for our times

Abstract: Of grave concern is the decline in the reliability of our bulk electric power systems brought on by restructuring. Conditions on our transmission systems have affected the installed capacity needed and how it should be operated. Some of the existing software packages that are being used to make reliability evaluations and to plan and operate systems are inadequate and should be used with careful restraint while new tools are being developed and coordinated with evolving institutional arrangements. To solve our reliability problems, additional technology is needed. Those developing needed software and computer methods should be made aware of the problems that are occurring on our transmission system and what it will take to solve them. This article provides some specific examples of these areas of concern.

Design tool generates substation interlock schemes

Abstract: The power of object-oriented programming in a Windows environment has been used to design a software application that automatically generates switching schemes that satisfy specified interlocking criteria. The application has two components, one for generating interlocking schemes from substation data and the other for generating switching instructions and implementing them. The connectivity of substations, parameters of switches and components, and interlocking constraints are used by the software as input data. While this generalised tool expedites the development of interlocking schemes, its use is not limited to specific substation configurations. Three out of the many designs prepared are presented in this paper to demonstrate its usefulness.

Get a clear view of simulated and measured data

Abstract: Present-day operating systems have graphical user interfaces (GUI) that are of great help in designing good user interfaces for application programs. Also, there have been dramatic improvements in computer power and power-to-price ratio. Acknowledgement is growing, even in technical environments, that good man-machine interfaces (MMI) have so many advantages that they are worth the effort of design and implementation. A good MMI can reduce the chance of making trivial errors that could be detected only very late during the simulation process, resulting in a great deal of wasted time. Nevertheless, in the electrical engineering community, programs that are not optimal on the MMI side are still in use. This article focuses on a study of the MMI main issues for a plotting program to visualize simulation and measurement data effectively. The resulting program, PlotXY, was developed in the rapid application development (RAD) environment of Borland C++ Builder, which is distributed for free and described in this article, along with the main ideas behind its interface.

Design tool optimizes overhead line profiles

Abstract: The authors describe a spreadsheet-based tool which enables overhead power line engineers to alter the pole locations of transmission lines on an incremental basis, view the line profile drawings and make optimal design decisions.

Reengineering a motor and drive simulation tool

Abstract: As the complexity and diversity of the application of DC and AC motor drives has increased, so too has the occurrence of problems that are often caused by the interaction between the components of the system. The actual problem and its associated concepts are termed the problem domain. Computer simulation of drives provides an economical means of analyzing drive systems in a controlled environment to ensure that the system is stable and operates as required. The means to input, process and extract the data from the simulation is termed the solution domain. This article examines the process of reengineering the CASED drive simulation package so that it can be accessible to engineers whose main forte is electrical machines and drives and who are not simulation specialists. The objective is to bring the solution domain closer to the problem domain.