A comparative analysis of digital relaying algorithms for the differential protection of three phase transformers
TL;DR: The authors present a survey and a comparative analysis of various algorithms introduced for the differential protection of three-phase transformers and assesses how well they address the two subproblems of differential protection per se and exciting-current detection.
Abstract: The authors present a survey and a comparative analysis of various algorithms introduced for the differential protection of three-phase transformers. After a brief review of the concept, the problems associated with the differential protection of transformers, and the existing solutions as implemented with conventional (electromagnetic) relays, the algorithms introduced for digital relaying are outlined. Some of these algorithms are derived from conventional protection methods while others represent novel methods. They are analyzed in view of how well they address the two subproblems of differential protection per se and exciting-current detection. Finally, a simple ranking procedure is introduced. Two optimality performance indices, based on time and frequency, are defined and used as a basis for a comparison of the algorithm presented. >
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Book•
01 Jul 1988TL;DR: In this paper, the authors present a comprehensive, up-to-date account of computer relaying in power systems, based in part on the author's extensive experience in the field.
Abstract: This text/reference presents a comprehensive, up-to-date account of computer relaying in power systems, based in part on the author's extensive experience in the field. Provides background material on current relaying practices, and covers the mathematical foundations for relaying algorithms. Each chapter contains helpful illustrations, examples, and problems.
880 citations
TL;DR: A comparative study of algorithms for digital differential protection of power transformers as to their speed of response, computational burden and capability to distinguish between an inrush and transformer internal fault.
Abstract: A comparative study of algorithms for digital differential protection of power transformers is reported. The mathematical basis for each algorithm is described. The algorithms are compared as to their speed of response, computational burden and capability to distinguish between an inrush and transformer internal fault. >
181 citations
TL;DR: In this paper, an artificial neural network (ANN) was applied to inrush detection and reconstruction of distorted secondary CT currents due to saturation, which improved the reliability of the protection operation.
Abstract: This paper suggests the possibility of improving digital power transformer protection. The establishment of inrush in power transformers is becoming unreliable in existing numerical protection. An artificial neural network (ANN) was applied to inrush detection. The saturation of protective current transformers (CT) cannot be totally eliminated despite proper dimensioning. ANN was used for the reconstruction of distorted secondary CT currents due to saturation. In both cases, an ANN was included in the protection algorithm as an extension of the existing methods, which improved the reliability of the protection operation. The paper presents the digital protection algorithm completed in this way and the laboratory equipment by means of which experimental results were obtained. The results confirm faster and more reliable recognition of transformer inrush, as well as satisfactory reconstruction of the distorted secondary CT currents.
129 citations
TL;DR: The fuzzy logic based multi-criteria protective relay for a three-phase power transformer is presented and shows significant gains in both sensitivity and selectivity of the self-organized relay compared with traditional approaches.
Abstract: In the paper the fuzzy logic based multi-criteria protective relay for a three-phase power transformer is presented. Twelve criteria used to stabilize the relay are introduced and integrated by means of multi-objective decision-making methods. The introduced protection scheme contains several internal functions and coefficients which are subject to off-line pre-installation self-setting. Three unique procedures are delivered for self-adjusting the relay, and thus, making it self-organized. The results of testing show significant gains in both sensitivity and selectivity of the self-organized relay compared with traditional approaches.
66 citations
TL;DR: In this paper, an ANN subroutine was used to discriminate internal faults from other situations, replacing the traditional Fourier method for harmonic restraint, and a routine for reconstruction of saturated current signals based on recurrent ANNs was also proposed.
Abstract: This paper presents alternative approaches using artificial neural networks (ANNs) for the protection of power transformers. A complete protection scheme was implemented. An ANN subroutine was used to discriminate internal faults from other situations, replacing the traditional Fourier method for harmonic restraint. In addition, a routine for reconstruction of saturated current signals based on recurrent ANNs is also proposed. The proposed methods were extensively tested and then compared to the traditional differential protection algorithm, showing promising results. The application of the ANN tools is a new and important stage in the differential relay analysis methodology for power transformer protection
58 citations
References
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TL;DR: In this article, a fundamental basis has been developed for the use of a time-shared stored-program digital computer to perform many of the electrical power-system protective-relay functions in a substation.
Abstract: A fundamental basis has been developed for the use of a time-shared stored-program digital computer to perform many of the electrical power-system protective-relay functions in a substation. Logic operations are given to detect a fault, locate it, and initiate the opening of the appropriate circuit breakers, whether the fault is in the station or on lines radiating from the station.
225 citations
TL;DR: In this article, the authors present a technique which computes and uses flux-current relationship of the transformer to obtain the restraint function, which can be implemented on a microcomputer of modest capability.
Abstract: The paper begins with a review of techniques for computer based protection of multi-winding three-phase power transformers. After reviewing the principles of harmonic-restraint and voltage-restraint current differential protection, the paper develops a technique which computes and uses flux-current relationship of the transformer to obtain. the restraint function. It is shown that this protection technique requires fewer computations as compared to the harmonic current computation, and hence can be implemented on a microcomputer of modest. capability. The principle has been tested. in the'laboratory on a model power transformer. The relay based on this flux-restraint principle performs well on all the system phenomena simulated in the laboratory. It is expected that a relay based on this principle will be tested in the field on a power transformer.
168 citations
TL;DR: The principles of a method of transformer protection by digital computer are described, which is essentially an adaptation ion of harmonic-restraint differential protection.
Abstract: The principles of a method of transformer protection by digital computer are described. The method is essentially an adaptation ion of harmonic-restraint differential protection.
80 citations
TL;DR: In this paper, simple recursive expressions for the harmonics using a sampling rate of 12 times a cycle were given for a three-phase, three-winding power transformer, which were used as the basis for a one cycle algorithm which was compatible with proposed digital line protection schemes.
Abstract: This paper presents an algorithm for digital protection of a three-phase, three-winding power transformer. Simple recursive expressions are given for the harmonics using a sampling rate of 12 times a cycle. These expressions are used as the basis for a one cycle algorithm which is compatible with proposed digital line protection schemes. The algorithm was tested on data obtained from a model transformer. Test results are given for 19 cases of energizations and faults.
59 citations
DOI•
01 Mar 1982TL;DR: Using the rectangular transform technique, a fast and accurate algorithm has been developed for transformer protection using the Fourier coefficients by addition and subtraction routines only, which is quite suitable for microprocessor-based protection of power systems.
Abstract: A simple algorithm for fast computation is an important requirement for the efficient application of microprocessors in power-system relaying Using the rectangular transform technique, a fast and accurate algorithm has been developed for transformer protection The algorithm generates the Fourier coefficients by addition and subtraction routines only The method provides good discrimination between the nonzero differential current produced by the transformer energisation and that produced by internal faults The algorithm provides fast fault detection and yields a large blocking signal, using second or higher harmonic components The digital simulation and test results on a variety of fault and inrush conditions, including the periodic inrush ones, clearly demonstrate the efficacy of this algorithm for the protection of the power transformer Furthermore, owing to the relative simplicity and absence of time consuming multiplication and division calculations, the algorithm is quite suitable for microprocessor-based protection of power systems
31 citations