• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.333_335
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• 2009

It is expected, in the near future, that the use of distributed generation systems should be increased considerably. In this case, distance relay algorithm should be developed in the manner that it can reduce the error due to the in-feed effect. This paper presents a method to consider the fault current rushed from the remote end of a line. In the steady-state, the relays in both ends exchange the voltages of upper nodes. If a fault is perceived, the relay calculates fault location taking the fault current from the remote end by using voltage data of the remote ends obtained just before the fault. Even though this method has inevitable error, it can show more precise fault allocation. The suggested method is applied to a typical transmission system with two power sources in both ends to verify its effectiveness.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.8
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• pp.432-437
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• 2004

Since the characteristic frequency is decreased in proportion to the fault distance, the characteristic frequency component may be insufficiently eliminated by a low-pass filter on a long transmission line. In order to set a standard for the cut-off frequency of the low-pass filter, this paper proposes a method for obtaining the characteristic frequencies due to line faults. The application results of the proposed method are presented for line to ground (LG) faults and line to line (LL) faults on a 345 kV 200 km overhead transmission line. The EMTP is used to generate fault signals under different fault locations and fault inception angles. By comparison between the characteristic frequencies obtained from the proposed method and the EMTP simulation, it is shown that the proposed method accurately obtains the characteristic frequency.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.3
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• pp.146-152
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• 2001

This paper describes an accurate fault location algorithm based on sequence current distribution factors for a double-circuit transmission system. The proposed method uses the voltage and current collected at only the local end of a single-circuit. This method is virtually independent of the fault resistance and the mutual coupling effect caused by the zero-sequence current of the adjacent parallel circuit and insensitive to the variation of source impedance. The fault distance is determined by solving the forth-order KVL(Kirchhoff's Voltage Law) based distance equation. The zero-sequence current of adjacent circuit is estimated by using a zero-sequence current distribution factor and the zero-sequence current of the self-circuit. Thousands of fault simulation by EMTP have proved the accuracy and effectiveness of the proposed algorithm.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.516-518
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• 2005

This paper presents a distance protection algorithm a lied to the linked line for interconnecting wind farm with the utility. The capacity of wind farm is lower than utility system and its fault current level is very low. When a high resistance fault occurs in the linked line, it is difficult to detect accurate fault distance because of reactance effect. By using the characteristic of equivalent source impedance of induction generator which is compensated by capacitor bank and characteristic of the capacity of wind farm, this paper proposes improved distance protection algorithm applied to the linked line. A series of PSCAD/EMTDC simulation results have shown effectiveness of the proposed algorithm.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.871-874
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• 1997

A new typed distance relaying scheme is proposed. Artificial neural networks are applied to the distance relaying system composed of pattern recognition based. The proposed distance relaying scheme have the two block of pattern recognition stages to estimate the fundamental frequency and to classify the fault types. The advantage of this approach is demonstrated by the random waves and the fault transient wave signals of EMTP(electromagnetic transients program) in power systems fault conditions. The proposed method is compared with the conventional method and the simulation results show the efficiency of the neural networks.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.1
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• pp.38-44
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• 2001

For double-circuit transmission line systems, an accurate digital distance relaying algorithm immune to the reactance effect is proposed. The apparent impedance calculated by the distance relay is influenced by the combined reactance effect of the fault resistance and the load current as well as the mutual coupling effect caused by the zero-sequence current of the adjacent parallel circuit. To compensate the magnitude and phase of the estimated impedance, this algorithm uses phase angle difference between the zero(positive) sequence of the both side of the system seperated by the fault point. The impedance measuring algorithm presented used a current distribution factor to compensate mutual coupling effect instead of the collected zero-sequence current of the adjacent parallel circuit.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.334-336
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• 2003

This paper describes the influences of the large scaled wind farm interconnected with 154 kV power networks on the operational characteristics of distance relay applied in the transmission line. The wind farm composed of wind turbine generators are one of the great energy sources: they can supply the power into an interconnected network not only the normal conditions, but also the fault conditions of power network. Therefore, the distance relay applied in the transmission tine may mal-operate due to the contribution of wind farm. This paper presents the operational characteristics of distance relay for the fault occurred in the transmission line interconnected with wind farm. Simulation results show that it is difficult to recognize the fault location due to the power output of wind farm.

• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.286-288
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• 1998

A digital distance relaying algorithm immune to the effect of the fault resistance in single-phase to ground fault is proposed. The power frequency components of relaying signals are extracted by the 1 cycle DFT. To compensate the magnitude and phase of the estimated impedance, which is calculated by the general method, this algorithm uses phase difference between the zero sequence impedance of networks on both sided of the system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.11
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• pp.2095-2100
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• 2009

Since most of the Extra High Voltage (EHV) transmission lines are untransposed and multi-circuits, errors are occurred inevitably because of the unbalanced impedances of the lines and so on. Therefore, a distance relaying algorithm applicable to the untransposed multi-circuits transmission lines needs to be developed. The proposed algorithm of fault location estimation in the paper uses the fundamental phasor to reduce the effects of the harmonics. This algorithm also analyzes the second-order difference of the phasor to calculate the traveling times of waves generated by faults. The traveling time of the waves generated by faults is derived from the second-order difference of the phasor. Finally, the distance from the relaying point to the faults is estimated using the traveling times. To analyze the performance of the algorithm, a power system with the EHV untransposed double-circuit transmission lines are modeled and simulated under various fault conditions such as several fault types, fault locations, fault inception angles and fault resistances. The results of the simulations show that the proposed algorithm has the capability to estimate the fault locations quickly and accurately.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.3
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• pp.219-226
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• 1992

In this study, Kalman filtering theory is applied to the estimation of symmetrical components from fault voltage and current signal when it comes to faults with the power system. An algorithm for estimating fault location accurately and quickly by calculating the symmetrical components from the extracted fundamental voltage phasor and current phasor is presented. Also, to confirm the validity of digital distance relaying techniques using Kalman filtering, the experimental results obtained by using the digital simulation of power system is shown.