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Showing papers on "Power-system protection published in 1986"


Journal ArticleDOI
TL;DR: In this paper, the problem of topological observability in power system state estimation is addressed and a new observability algorithm using a network flow technique is presented, which is explained with reference to the IEEE-5 bus system and its performance is evaluated using the IEEE30 and IEEE-118 bus systems.
Abstract: This paper addresses itself to the problem of topological observability in Power System State Estimation. After giving a brief theoretical background a new observability algorithm using a network flow technique is presented. The algorithm is explained with reference to the IEEE-5 bus system and its performance is evaluated using the IEEE-30 and IEEE-118 bus systems.

435 citations


Journal ArticleDOI
Chihiro Fukui1, Junzo Kawakami1
TL;DR: An expert system which can estimate possible fault sections using the information on operating protective relays and tripped circuit breakers and is written in Prolog.
Abstract: This paper deals with an expert system which can estimate possible fault sections using information from protective relays and circuit breakers. This system is applicable to dispatching centers and can help dispatchers to judge emergency situations as the first step in restoration procedures. When some faults occur, the system makes inferences based on both knowledge about protection systems and information on the operating protective relays and tripped circuit breakers. The system can give possible answers even in the case of multiple faults and false operations of relays and circuit breakers. This expert system is written in Prolog.

238 citations


Journal ArticleDOI
TL;DR: This paper describes two knowledge-based programs that simulates the behavior of automatic protection schemes in power networks and an expert system for the diagnosis of faults coded in OPS5--a widely available language for writing rule- based programs.
Abstract: This paper describes two knowledge-based programs. The first simulates the behavior of automatic protection schemes in power networks. The second is an expert system for the diagnosis of faults. Both are coded in OPS5--a widely available language for writing rule-based programs. The user and the programs communicate over a Blackboard which is a database for messages. The Blackboard has been organized so that the addition of new programs, whether knowledge-based or algorithmic, will be relatively easy.

105 citations


DOI
V. Cook1
01 Sep 1986
TL;DR: In this article, the influence of pre-fault load on the distance-to-failure measurement problem is analyzed and a new method of accounting for load effects is presented, which is applicable to any system arrangement and is suitable for a wide range of fault resistance values.
Abstract: The paper considers fundamental problems involved in the precise location of faults on high-voltage transmission lines. The influence of pre-fault load on the distance-to-fault measurement problem is analysed and a new method of accounting for load effects is presented. Two of the algorithms considered are precise, containing no simplifying assumptions and their overall accuracy is limited only by the accuracy of digital impedance relays at both ends of the protected circuit. A third algorithm presents a new approach to the fault location problem, which requires digital impedance relays at one end only of a transmission line. The procedures described are applicable to any system arrangement and are suitable for a wide range of fault resistance values.

74 citations


Journal ArticleDOI
A.T. Johns1, M. A. Martin, A. Barker, E. P. Walker, P. A. Crossley 
TL;DR: In this article, the performance of superimposed component directional relays is discussed, and it is shown that the basic directional criteria can be violated due to travelling wave phenomena or for fault occurrence approaching a voltage zero.
Abstract: Some problems concerning the performance of superimposed component directional relays are discussed, and it is shown that the basic directional criteria can be violated due to travelling wave phenomena or for fault occurrence approaching a voltage zero. A relay design is developed using digital signal processing techniques to overcome these problems. Tlhe complete relay is tested using a typical 40OkV transmission line application.

38 citations


Journal ArticleDOI
TL;DR: In this paper, the transistor is protected against short-circuit using a modified autoregulated and autoprotection drive circuit and the experimental results show that the switching power loss and voltage stress in the device can be reduced by suitable choice of the switching-aid network component values.
Abstract: The present trend in the industry is towards the use of power transistors in the development of efficient Pulsewidth Modulated (PWM) inverters, because of their operation at high frequency, simplicity of turn-off, and low commutation losses compared to the technology using thyristors But the protection of power transistors, minimization of switching power loss, and design of base drive circuit are very important for a reliable operation of the system The requirements, analysis, and a simplified procedure for calculation of the switching-aid network components are presented The transistor is protected against short circuit using a modified autoregulated and autoprotection drive circuit The experimental results show that the switching power loss and voltage stress in the device can be reduced by suitable choice of the switching-aid network component values

15 citations


Journal ArticleDOI
TL;DR: In this paper, the authors deal with the stability aspect of a six-phase system in greater detail, defining a new transformation and calculation of critical clearing angles under fault and coming to the conclusion that the six phase system is more stable compared to the original and upgraded three-phase double circuit lines.
Abstract: Recently, there is a growing interest on the concept of six phase transmission as an alternative to the voltage upgradation of a line, to increase the power transfer capability, within the existing right of way. Allegheny Power System has been investigating the conversion of some of their 138 kV three phase double circuit lines to 138 kV six phase lines as an alternative to 230 kV three phase double circuit lines. So far, the stability aspect of a six phase system has been only estimated approximately from the possible power transfer capability under fault. This paper deals with the stability aspect of a six phase system in greater detail, defining a new transformation and calculation of critical clearing angles under fault and comes to the conclusion that the six phase system is more stable compared to the original and upgraded three phase double circuit lines.

9 citations


Journal ArticleDOI
TL;DR: In this paper, a submarine cable fault detection system was developed for DC line protection of the Hokkaido-Honshu HVDC Link, where DC currents at both cable heads change mutually in the reverse direction.
Abstract: For DC line protection of the Hokkaido-Honshu HVDC Link, a submarine cable fault detection system was developed. In this system, a DC line fault is declared when DC currents at both cable heads change mutually in the reverse direction. Combining this detection system with a current difference detection system which operates for any fault occurring on the high voltage DC transmission line, the high voltage DC line protection system is composed. Through the simulator tests and five-year field experience, the detection system has been verified to be satisfactory.

7 citations


Journal ArticleDOI
TL;DR: In this paper, the authors investigated the various sources of time delay, and presented a digital time delay compensation scheme, together with some test results, for EHV system protection.
Abstract: Processing of the fault transients for eliminating the unwanted signals, is essential. for the EHV system protection. The various components which perform this function, and the filters in particular, introduce a significant delay in the operation of the protective devices. The paper investigates the various sources of time delay, and presents a digital. time delay compensation scheme, together with some test results.

5 citations


Proceedings ArticleDOI
01 Oct 1986
TL;DR: In this paper, a modern microprocessor supervision system for correct charging control and monitoring the remaining protection time is presented, and a successful method for control and supervise such systems is explained.
Abstract: Improvement of the reliability of the static UPS-system is gained by using parallel-redundant systems. A successful method for control and supervise such systems is explained. To improve the availability, a modern microprocessor supervision system for correct charging control and monitoring the remaining protection time is presented.

4 citations


Journal ArticleDOI
TL;DR: In this article, a 4-terminal HVDC system with a microcomputer is used for converter control, and the performance of the 2-ACR method is evaluated.
Abstract: AC/DC simulator studies for a 4-terminal HVDC system have been carried out to demonstrate the operating performance of the multiterminal HVDC control scheme, "the 2-ACR method", which does not require fast communication systems. A microcomputer is used for converter control. Satisfactory operations have been confirmed through various types of simulations. Examples of an effective and economical DC circuit breaker application, for an AC system fault at the inverter and a DC line fault, are described.

Journal ArticleDOI
TL;DR: The need for sensitive ground fault protection is clarified in this paper by using known I2t techniques to examine the circuit components, such as relays, molded-case breakers, or overload relay heater elements.
Abstract: While many preferred methods exist for protecting components against damage from ground fault currents on 480-V systems, few analyses (if any) have been made concerning the effects on components (molded-case breaker, overload relay, etc.) due to a failure or absence of a ground fault protective device to clear a ground fault. Unlike fuses, which by definition could be considered self-protecting, no such feature exists in relays, molded-case breakers, or overload relay heater elements. The need for sensitive ground fault protection is clarified as by using known I2t techniques to examine the circuit components.

Journal ArticleDOI
TL;DR: The role of photovoltaics has played and will continue to play in experformance, in the field of electric power field, as discussed in this article, where the authors provide a better insight into exeiec prvd'swt odfudto frlal role.
Abstract: OBJECTIVE objectives to be discussed and shows how they relate one to another, leading to a positive future. Our past technology and I hope, in this discussion, to provide a better insight into exeiec prvd'swt odfudto frlal the role photovoltaics has played and will continue to play in experformance, inothe uspac powe fieldanion h tresial the electric power field. Photovoltaic specialists have made performance, i the space power field and es the terrestrtal significant accomplishments, of which we should be proud remote power field. Projections and trade-off studies over the and for which we should take proper recognition. Conversely, systems We now sitwna way to achieve competitive

Journal ArticleDOI
TL;DR: The Eagle 21? process protection upgrade system as discussed by the authors is a functional replacement for existing analog process protection equipment used to monitor nuclear power stations and to initiate the actuation of the reactor trip and engineering safeguards systems.
Abstract: Commercial nuclear power plants need equipment that increases plant availability, reduces test time and is both self-diagnostic and user-friendly. Westinghouse's Process Protection Upgrade System, called Eagle 21?, is a functional replacement for existing analog process protection equipment used to monitor nuclear power stations and to initiate the actuation of the reactor trip and engineering safeguards systems. Periodic testing of this protection equipment is required by industry regulations, and the advent of microprocessor systems has made it possible for plant test personnel to do this required testing in a short time, with great precision, and with few or no errors. The architecture of the testing system is described and the major benefits are highlighted.

Journal ArticleDOI
TL;DR: In this article, the principle of fault detection and its simulator study, principal circuitry, field test results and field performance records on the neutral line protection system for an HVDC transmission system are described.
Abstract: This paper described the principle of fault detection and its simulator study, principal circuitry, field test results and field performance records on the neutral line protection system for an HVDC transmission system. In the protection system, 125 Hz ac current injected to the neutral line is utilized as a pilot current to detect the neutral line faults. The pilot current injection is made through the neutral line surge capacitor without detracting its capability. Combined with a metallic return protecting breaker, this protection system has demonstrated a satisfactory performance on the grounding fault clearance without interrupting the power transmission.

Journal ArticleDOI
TL;DR: In this paper, a discrete state-space model of the response of both the utility's and the dispersed storage and generation's protection equipment to shunt and series faults on an electric distribution feeder is developed.
Abstract: This paper formulates a methodology to aid in deciding on the appropriate quality and quantity of protection equipment required for a small electric power producing device, known in the industry as dispersed storage and generation (DSG). In this methodology, a discrete state-space model of the response of both the utility's and DSG's protection equipment to shunt and series faults on an electric distribution feeder is developed. The parameters of the model are linked to the component reliabilities of the protection schemes and the specific characteristics of the distribution system. The mathematics of semi-Markov theory are used in the methodology to calculate the expected annual damage costs for various protection schemes. The total costs are calculated for alternative protection schemes by considering equipment damaqe, repair time, lost revenue, outage costs, and time spent in different operating states during the hazardous conditions. This methodology is useful to electric utilities, small power producers, and regulatory bodies who must make decisions regarding the adequacy as well as the cost-effectiveness of protection requirements for DSG installations.

Journal ArticleDOI
TL;DR: In this article, it was found that the reduction to 2 seconds for maximum through faults on transformers and the necessity to include a value for system impedance in the specification of the larger transformers will have significant effects on previous practices for planning, protection, operations, loading and specification.
Abstract: The recent revisions (1980-1983) to the standards for power transformers in both the U.S.A. and Canada call for corresponding revisions in many related planning and protection practices. Particularly, it is found that the reduction to 2 seconds for maximum through faults on transformers and the necessity to include a value for system impedance in the specification of the larger transformers will have significant effects on previous practices for planning, protection, operations, loading and specification. This paper discusses a number of these effects, with an emphasis from a protection point of view.

Proceedings ArticleDOI
01 Oct 1986
TL;DR: In this article, a current limit module (CLM) is proposed to limit short-circuit currents to values in magnitude of nominal currents of the equipment to prevent surge currents, a.o. inrush currents etc.
Abstract: One of the most important problems, when designing the power distribution in modern exchanges, is to minimize the effects of hazardous transients on the feeding voltage. Components which are used today - anything from transistors to intelligent integrated circuits - are more sensitive than their more simple precursors. Ericsson's construction practice is to minimize transients to harmless levels that are within the static and dynamic characteristics of electronic exchanges. Transient suppression can be achieved in different ways. For large telecommunication plants, this is solved by Ericsson, with high ohmic (≫45 m?) distribution. A short circuit current is, in this system, limited to maximum 1,000 A by the high resistance distribution cable. The voltage drop in the power distribution is kept at an acceptable level by means of voltage division between the battery circuit resistance and the resistance in the distribution cable. However, high ohmic distribution is not effective as transient suppression in small systems with short cables and small batteries, such as PABX-systems. In this paper an Current Limit Module for transient protection is described. It has been developed by Ericsson Power Systems, (a division of RIFA) for the Swedish PTT. The function of this module is to limit short circuit currents to values in magnitude of nominal currents of the equipment. The CLM prevents all types of surge currents, a.o. inrush currents etc. The CLM which is a very compact hybridized module can easily be built into any distribution system.

Journal ArticleDOI
01 Jan 1986
TL;DR: In this paper, the required performance of two types of pole-slipping relay which utilise the principle of impedance measurement was discussed and the difficulties with this method of measurement, as revealed by model machine and system tests, in distinguishing between pole sliding and certain types of fault conditions.
Abstract: The paper is a follow-up to the paper written by Stalewski, Goody and Downes for the Second IEE International Conference on Developments in Power System Protection in 1980. The paper discusses the required performance of two types of pole-slipping relay which utilise the principle of impedance measurement and explains the difficulties with this method of measurement, as revealed by model machine and system tests, in distinguishing between pole-slipping and certain types of fault conditions. It describes the logic criteria developed for each relay to overcome these problems. The paper also describes the principles involved for the relay installation at Dinorwig, in determining how far each relay should reach in order to detect remote pole-slips.