• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.9
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• pp.44-49
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• 2011

Due to increase of fault current, various superconducting fault current limiter (SFCL) are researched. We studied a power distribution system with SFCL. Along the way, we knew characteristics of fault current according to a distance from substation to fault point. Fault current is reduced by distance`s increase from substation. Also, SFCL.s effects are decreased by distance too. Therefore, we analyzed the fault current by a distance from substation to fault point when a SFCL was applied into a power distribution system. We simulated using a PSCAD/EMTDC.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.3
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• pp.183-192
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• 2003

This paper presents the real-time implemented distance relay algorithm which the fault distance is estimated with only local terminal information. When a single-phase-to-earth fault on a two-parallel transmission line occurs, the reach accuracy of distance relay is considerably affected by the unknown variables which are fault resistance, fault current at the fault point and zero- sequence current of sound line The zero-sequence current of sound line is estimated by using the zero sequence voltage which is measured by relaying location Also. the fault resistance is removed at the Process of numerical formula expansion. Lastly, the fault current through a fault point is expressed as a function of the zero-sequence current of fault line, zero-sequence current of sound line, and line, and fault distance. Therefore, the fault phase voltage can be expressed as the quadratic equation of the fault distance. The solution of this Quadratic equation is obtained by using a coefficient of the modified quadratic equation instead of using the square root solution method. After tile accurate fault distance is estimated. the mote accurate impedance is measured by using such an information.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.1
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• pp.25-30
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• 2005

An accurate digital distance relaying algorithm which is immune to mutual coupling effect and reactance effect of the fault resistance and the load current for the line faults in 765kV untransposed transmission lines is proposed. The algorithm can estimate adaptively the impedance to a fault point independent of the fault resistance. To compensate the magnitude and phase of the apparent impedance, this algorithm uses the angle of an impedance deviation vector. The impedance correction algorithm for phase-to-ground fault and phase-to-phase short fault use a voltage equation at fault point to compensate the fault current at fault point. A series of tests using EMTP output data in a 765kV untransposed transmission lines have proved the accuracy and effectiveness of the proposed algorithm.

• Proceedings of the KIEE Conference
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• summer
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• pp.452-454
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• 2004

An accurate digital distance relaying algorithm which is immune to reactance effect of the fault resistance and the load current for phase-to-ground fault in 765kV untransposed transmission lines is proposed. The algorithm can estimate adaptively the impedance to a fault point independent of the fault resistance. To compensate the magnitude and phase of the apparent impedance, this algorithm uses the angle of an impedance deviation vector. The impedance correction algorithm for Phase-to-ground fault uses a voltage equation at fault point to compensate the fault current at fault point. A series of tests using EMTP output data in a 765kV untransposed transmission lines have proved the accuracy and effectiveness of the proposed algorithm.

• Proceedings of the KIEE Conference
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• summer
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• pp.455-457
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• 2004

An accurate digital distance relaying algorithm which is immune to reactance effect of the fault resistance and the load current for phase-to-phase short fault in 765kV untransposed transmission lines is proposed. The algorithm can estimate adaptively the impedance to a fault point independent of the fault resistance. To compensate the magnitude and phase of the apparent impedance, this algorithm uses the angle of an impedance deviation vector. The impedance correction algorithm for phase-to-phase short fault uses a voltage equation at fault point to compensate the fault current at fault point. A series of tests using EMTP output data in a 765kv untransposed transmission lines have proved the accuracy and effectiveness of the proposed algorithm.

• The Journal of the Korea institute of electronic communication sciences
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• v.3 no.4
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• pp.276-281
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• 2008

Because the distribution systems experience frequently the fault by several causes, the identification task of fault location plays very important role in the view point of power supply reliability. The distribution systems are designed as radial structure with three-phase and single-phase branch line to supply the electric power to the widely dispersed loads, and it have a several load taps within each line segment. it makes the accurate fault distance determination difficult. Accordingly in this papers, the existing fault point determination methods are surveyed and analyzed, and then a fault distance determination method for distribution feeder is adopted which can be executed effectively in DAS center. Finally, the adopted method is verified using EMTP simulation.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.502-503
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• 2006

If the fault occurs on the underground Power cable system, the fault current on the sheath has the influence on all sections because it's returned through earth at the directly grounded point and operation point of SVL(Sheath Voltage Limiter) at joint box. Therefore, the earth resistance and the operation of SVL have an effect on the zero-sequence current. Then the impedance between relaying point and fault point is Increased. That causes the overreach of distance relay. For these reasons, the distance relay algorithm for protecting of the underground power cable systems was developed. It effectively advance the errors using ACI(Advanced Computing Intelligence) technique. In this algorithm, the optimization was performed by fuzzy inference system and genetic algorithm.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.2
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• pp.172-178
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• 2008

If the fault occurs on the underground power cable systems, the fault current on the sheath has an influence on all sections of cable because it's returned through earth at the directly grounded point and operation point of SVL(Sheath Voltage Limiter) on each insulated joint box. Therefore, the earth resistance and the operation of SVL have an effect on the zero-sequence current, and then the impedance between relaying point and fault point is increased. That causes the overreach of distance relay. For these reasons, the distance relay algorithm for protecting an underground power cable systems hasn't been developed till now. In this paper, new distance relay algorithm is developed for protecting a underground power cable system using fuzzy inference system which is the one of ACI(Advanced Computational Intelligence) techniques. This algorithm is verified by EMTP simulation of real power cable system, and proves to effectively advance the errors

• Proceedings of the KIEE Conference
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• 2001.05a
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• pp.259-261
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• 2001

An accurate digital distance relaying algorithm which is immune to the combined reactance effect of the fault resistance and the load current is proposed. The algorithm can estimate adaptively the impedance to a fault point independent of the fault resistance. To compensate the apparent impedance, this algorithm uses iteratively the angle of an impedance deviation vector improved step by step. The impedance correction algorithm for ground faults uses a current distribution factor to compensate mutual coupling effect.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.3
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• pp.168-174
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• 2004

This paper describes a new fault location algorithm based on the voltage equation at the relaying point using 6-phase current for untransposed 765㎸ parallel transmission lines. The proposed method uses the voltage and current collected at only the local end. By means of 3-phase circuit analysis theory to compensate the mutual coupling effects between parallel lines, the fault location is derived. The fault distance is determined by solving the 2nd distance equation based on KVL(Kirchhoff's Voltage Law). Extensive simulation results using EMTP(Electromagnatic Transients Program) have verified that the error of the fault location achieved is up to 4.56(%) in untransposed parallel transmission lines.