Showing papers on "Power-system protection published in 1984"

Computer Aided Transmission Protection System Design Part I: Alcorithms

Abstract: The role of a computer-aided-design tool in assisting protection engineers is defined. In the process, we identify three computational problems for which algorithms are not readily available: network analysis to find primary/backup relay pairs, setting directional overcurrent relays and setting distance relays. Suitable algorithms for each of these tasks are presented.

A Comparison of 100 Percent Stator Ground Fault Protection Schemes for Generator Stator Windings

Abstract: This paper describes three different schemes for detecting single-phase-to-ground faults in 100% of the generator stator winding. The operating theory, a setting example, and field measurements are provided for each of the three schemes. A chart comparing the significant application characteristics of the three schemes is presented.

Electric Distribution Protection Problems Associated with the Interconnection of small, disperesed Generation Devices

Abstract: This paper discusses the results of simulating three potential protection problems associated with the interconnection of rotating-type, small dispersed storage and generation (DSG) devices to the electric distribution system. These simulations were performed as part of a study to address the-adequacy of the electric utility industry's present protection practices and hardware for distribution systems with DSG. The simulations considered phenomena such as the effect of dispersed generati, on infeed on the coordination of fuses, resonance of an isolated section of feeder with a three-phase DSG device, and the islanding of a DSG device on an isolated feeder. The phenomena were simulated for a 12. 47 kV feeder with DSG. A digital computer program was used to calculate the transient currents and voltages produced on the feeder for the three types of phehomena. Results of the simulations indicate that these are concerns which should be considered by electric utilities in the connection of dispersed generation sources to the electric distribution system.

Improved Interfacing of Electrical Machine Models to Electromagnetic Transients Programs

Abstract: A new technique is presented for interfacing electrical machine models with electromagnetic transients programs. The machine models with their associated controls, loads or turbines can be assembled as subroutines by the user and interfaced to the electrical network or other machine models directly. The machine models employ the standard state variable equations and may use any integration technique for solution. The technique does not require a Thevenin equivalent circuit of the electrical network.

Reliability Modeling of Protective Systems

Abstract: Electric power systems are comprised of a very large number of interconnected components that are designed for the sole purpose of generating and delivering electrical energy to consumers. Usually, the consumers are free to accept or-reject the available electrical energy at will, suggesting a probabilistic rather than deterministic demand pattern. The system is operated by humans and by automatic control apparatus, both having some probability of failure to perform their function. Moreover, the system physical components are subject to failure in some random way, with each failure often requiring corrective action. Since the system is geographically extensive, it is subject to a large number of natural and man-made hazards. Examples are lightning induced faults and physically damaged components that result from natural or man-made causes. For the purpose of this discussion we classify all of the above as disturbances. Some of these disturbances, such as short circuits, cause severe upsets in system operation and must be somehow removed or isolated. This is the role of the 'protective systems,' which are installed throughout the power system, to detect and remove hazardous disturbances, which we usually call faults.

Method of using data from computer simulations to test protection equipment

Abstract: The paper describes a computer-aided protection evaluation equipment which has been developed primarily to investigate protective relay performance during the period immediately following fault inception. Modern mathematical techniques allow the transient behaviour of a power system to be determined and the equipment described permits this calculated information to be used to evaluate relay performance. The equipment comprises two main elements—a simulation executed on a computer and a means of using the simulation to test protective relays. Novel techniques are described for removing sampling effects from the analogue signals, for small signal modelling of transducers and for the evaluation of unit protection schemes by the simultaneous application of currents and voltages from two points on a power system. Both the hardware and operating software are detailed and information is given concerning the computer simulation of the power system.

Protection of industrial power systems

Abstract: Simple protection devices relays current and voltage transformers for protection fault calculations time-graded overcurrent protection unit protection transformer protection feeder protection motor protection generator protection control circuits testing.

New Type Power Line Carrier Relaying System with Directional Comparison for EHV Transmission Lines

Abstract: This thesis suggests and studies a new type power line carrier protective relaying system with directional comparison for EHV transmission lines It consists of the following three important improvements: (a) Adoption of the phase compensator type directional relay suggested and studied by the authors which can operate correctly in two phase operating conditions of the protected line;(b) with constant circulation of carrier frequency blocking current;(c) to take advantage of sudden decrease of received carrier signal level in case of internal three phase faults Theoretical analysis, experimental data and field operating experience are given

Evaluation of Grid-Connected Inverter Power Systems: The Utility Interface

Abstract: Dispersed electrical generation connected into the U.S. utility grid is a promising way to increase energy production. However, to assure technical compatibility of the grid and potentially large numbers of these small generation sources, an engineering evaluation effort is required. Work is presented that is currently under way to test inverter power systems in a grid-connected environment. The technical details of the tests related to utility interface and of the special equipment required to conduct them are described. Results from testing grid-connected inverters for photovoltaic applications will be examined.

Study of Time Dissemination Methods Used on an Electric Power System with Particular Reference to Hydro-Quebec

Abstract: An analysis of the most important time dissemination methods in current use is presented and the difficulties encountered or foreseen in applying such methods in electrical substations is described. The latter part of the paper is devoted to methods developed and applied at Hydro-Qu??bec. There are many requirements for a common time scale in electric power systems. For example, interest has arisen in the chronology of protection operations, where the accuracy must be in the order of milliseconds. A more recent application is for measurement of the voltage phase-angle (or power angle) between remote points on a power system, a technique which calls for an accuracy in the order of 10 ??s. A distinction is established here between time dissemination and frequency dissemination, which are often confused.

Distribution System Protection with Decentralized Generation Introduced into the System

Abstract: Cogeneration from renewable energy sources has been universally proposed as a partial alternative to the solution of our nation's energy problems. New technical, safety, and operational problems are introduced when this generation is placed into a distribution grid. Addressed is the problem of distribution system protection with the introduction of cogeneration sources and the changes and modifications which may be required in the application of present-day protection devices. A sample system is considered, and system protection and coordination with and without cogeneration has been calculated through a digital fault and system protection coordination program. The results indicate through the study of several systems that additional coordination and protection considerations will be required when sizable cogeneration sources are introduced to maintain a high degree of reliability and service continuity.

Generator Ground Protection Guide

Abstract: The "Generator Ground Protection Guide" ANSI/IEEE Standard C37.101 has been prepared recently by the Power System Relaying Committee to aid in the application of relays and relaying schemes for the protection of synchronous generators for single-phase-to-ground faults in the stator winding. The various protective schemes along with recommended and alternate methods of protection for the most commonly used generator connections and grounding practices are covered. The purpose. of this paper is to review some of the highlights of the Guide, to familiarize the industry with the scope and usefulness of this new document, and to invite considered discussion for the purpose of improving this guide in the future.

A Novel Method of Detecting Asymmetrical Transformer Core Saturation Due to Gic

Abstract: A device based on the sensing of a unique symptom of sustained asymmetrical core saturation of a power transformer, due to geomagnetically induced currents (GIC), and thus indirectly indicating the presence of GIC in an EHV transmission line system, has been developed. The device can be used to achieve any of the following objectives: (1) As an alarm to permit the power system operator to take remedial measures if necessary to prevent further system disturbances during a severe geomagnetic storm. (2) As a control signal for inserting a preventive device designed to eliminate GIC-flow in the system. (3) As a blocking signal for preventing misoperation of existing protection schemes. (4) As an informative alarm signal for a false trip (if any) due to GIC, allowing the system operator to decide on the possibility of fast restoration.

Development of a PCM Current Differential Relaying System Using Fiber-Optic Data Transmission

Abstract: As demand for electric power has increased, EHV cable systems have been introduced into city areas; in this situation, problems of system protection that may arise when pilot-wire protection is used include electromagnetic induction, limitation of line length, etc. Last year, we solved those problems by developing a PCM current differential relaying system using fiber-optic data transmission. This system has been installed and operation has started on the 275 KV cable line (MINAMI OSAKA s/s -- SENBOKU s/s).

Microprocessor-Based Recloser Control: New Technology Distribution System Protection Capability

Abstract: Computer control and automated operation of electric utility systems have so far consisted of relatively large, complex control systems for substations and central dispatch centers. Full utilization of these control capabilities at the distribution level and complete automation of the distribution system will also require more sophisticated controls on the individual devices of the distribution system for both the substation and the distribution line itself. Microprocessors available at present allow the design of the controls needed to accomplish this.

A New Algorithm Of Digital Protection For Shunt Reactors

Abstract: This paper proposes a new digital protection scheme for shunt reactors. The method proposed here is based on the relationship between flux and current of shunt reactors and simulation results indicate that this type of relay is less affected by inrush phenomena than conventional impedance relays. The selection of cutoff frequency of Low Pass Filter (LPF), sampling interval and integral time is also discussed and their desirable values are estimated from the sensitivity analysis of these parameters.

High-Resistance Grounding and Selective Ground Fault Protection for a Major Industrial Facility

Abstract: The high-resistance grounded system offers the distinct advantage of service continuity under single ground fault conditions which is critical to many industries such as petroleum, chemical, mining, textile, cement, pulp and paper, food, glass, utility, etc. A new major phosphate mine, with a total of 120 MVA electrical demand capacity, utilizes the high-resistance grounding method for the 480-V and 4160-V distribution systems. A complete ground fault protection scheme that includes both first fault alarm and second fault selective tripping protection was developed for the proper protection of the system. The design of this ground fault protection system has many unique features due to the complexity of the project. Design considerations including the system leakage current, the limitation of transient overvoltage, the grounding methods, the fault detection and annunciation, and selective isolation of faults based on circuit priorities, are analyzed.

Control and Auxiliary Power Systems for Industrial and Commercial Switchgear Installations

Abstract: Protective relays for power systems are ineffective if no energy is available to actuate the circuit interrupter when a fault occurs. Therefore, control power systems deserve careful design attention. The design of both ac and dc control power systems is reviewed, and some design criteria for these systems are listed.

Innovative Features in the Electric Power Program at the OHIO State University

Abstract: This paper describes the electric power engineering program at The Ohio State University (OSU), and its characteristic features in the electric power systems, high voltage engineering, and electric machines area. The innovative features in laboratory courses are related to the existence and utilization of protective relays and test sets, a high voltage laboratory, scale model facilities (air models and electrolytic tanks), electronic motor controls, and dissectible machines. Several experiments are reviewed in detail, especially the operation of a mini power system. The computer applications area and the development of a power system research simulator are also reviewed.

Semiconductor fault-current limiters. Part 1: Problems connected with and possible schemes for implementing short-circuit current limitation in power systems

Abstract: Power systems are interconnected to improve system reliability, stability and economy of operation. Because of the large capacity of interconnected systems, the currents fed into faults assume enormous levels. Hence, the need for fault-current limiters (FCLs) particularly for protecting equipments with low ratings, from the consequences of excessive fault currents. A new approach in fault-current limiting in power systems makes use of high-power semiconductor devices, which offer enhanced reliability and improved performance over the conventional types of FCLs. This approach in fault-current limiting in power systems is discussed and a comparison with the existing FCLs is made.

Technical Council Generator Ground Fault Protection Using Overcurrent, Overvoltage, and Undervoltage Relays

Abstract: 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.

Computation of Frequency of Severe Power System Faults

Abstract: An analytical procedure is introduced to compute the frequency of single and multi-phase faults normally cleared or with delayed clearing at or near a major switching station. Data requirements are discussed and numerical examples are presented illustrating the method.

History of the Commercial Buildings Power Systems Committee

Abstract: FROM the 1950's and 1960's the Industrial and Commercial Buildings Power Systems Committee of the IEEE served as the home of the Commercial Buildings Subcommittee. Charles Maust was the Chairman in 1964 of this subcommittee at the time of the publication of the first modern version of the Gray Book. The subcommittee continued unchanged in structure until 1977 when the Commercial Buildings Subcommittee became the Commercial Power Systems Committee. Richard Koestner, was elected as the first Chairman of the Committee. The makeup of the Commercial Buildings Subcommittee (and later the committee) has always consisted of a relatively loyal cadre of engineers conversant with commercial building techniques. The very nature of commercial building design is such that almost all of the committee members are involved in related committees such as Systems Protection, Codes and Standards, and Industrial Power Systems. In addition to the cadre type of membership a number of individuals primarily active on other committees have a corresponding interest in commercial buildings and as such attend and participate in commercial buildings activities. The Commerical Buildings Committee is closely related to the Space Conditioning and the Production and Application of Light Committees. In fact, the Space Conditioning Committee, which is involved with heating and cooling of buildings and more lately the sophisticated control of building systems, has overlapping membership with the Commercial Buildings Committee. There has been a strong effort to coordinate the activities of the two committees, since building automation is becoming one of the most important aspects of commercial building design. From the early days of the Commercial Buildings Subcommittee the major emphasis was, and still is the Gray Book, IEEE Standard 241. A new publication which provides information on electrical systems for health care facilities is nearing completion. Over the years, in the move from subcommittee to committee status and with the creation of many more areas of activity, the need for expanded liaison intermeshing with the Production and Application of Light Committee, the Codes and Standards Committee, the Protection Committee, and others has been important. The Commercial Buildings Committee and the Space Conditioning Committee have often had common sessions at conferences. As time goes on, there will be an increasing emphasis in the area of building technical sophistication which will be reflected in the types of papers published and in newer editions of the Gray Book. The earliest edition of the Gray Book dealt primarily with building wiring and as editions have evolved, controls have been increasingly emphasized and the impact of electronic systems is now in vogue. It is interesting to note that the earlier chairmen of the subcommittees and committees were oriented in the power area of building design, but in later years individuals, such as Al Marden who has served as Chairman, have been heavily involved in the area of building control. Energy conservation has had a significant impact on the activities of the Commercial Buildings Committee and with common membership there has been participation with the Energy Subcommittee of the Industrial Power Systems Committee. The topics covered in the Commercial Buildings paper have included lighting, energy conservation, building automation rehabilitation, system protection, and high-rise designs; and of them are all prepared in a manner which reflects the unique commercial buildings aspects of design.

Generator Ground Protection Guide A working-group* report for the Power System Relaying Committee

Abstract: The Generator Ground Protection Guide ANSI/IEEE Standard C37.101 has been prepared recently by the Power System Relaying Committee to aid in the application of relays and relaying schemes for the protection of synchronous generators for single-phase-to-ground faults in the stator winding. The various protective schemes along with recommended and alternate methods of protection for the most commonly used generator connections and grounding practices are covered. The purpose of this paper is to review some of the highlights of the guide, to familiarize the industry with the scope and usefulness of this new document, and to invite considered discussion for the purpose of improving this guide in the future.

History of the Industrial Plants Power Systems Committee

Abstract: THE Industrial Plants Power Systems (IPPS) Committee is a committee of the Industrial Power Systems Department (IPSD) of the Industry Applications Society (IAS) of the Institute of Electrical and Electronics Engineers, Inc. (IEEE).

Application of Lightning and Surge Protection to Well Line Feeders

Abstract: The application of shielding and protection devices to an industrial power system for protection against damage and outages due to lightning strokes is described. The system is dedicated to the function of driving deep well pumps for a paper mill water supply. A description of the system is provided, together with a description of severe problems encountered due to lightning strokes. The basic approach to correction of problems is described, as well as the theoretical basis for selection of that approach. A mathematical analysis is presented to show that this approach rests on a sound physical foundation, and operating experience is presented, showing that during nine successive lightning seasons no problems related to lightning have occurred.