• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.2
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• pp.7-14
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• 1998

This paper presents an approach to quantitatively evaluate customers' effect due to automatic reclosing of power distribution systems. This proposed approach assess the customers' effect on equip ment halt by predicting a momentary interruption and voltage sag and analyzing the impact of customers' equipment sensitive to electric disturbances. Simulation results show that the increment of the number of reclosing improves the service reliability, but deteriorates the power quality for customers. The proposed approach utilizes the determination of automatic reclosing scheme and distribution system planning.anning.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.740-742
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• 1996

This paper analyzes the Impact of customer system at the transients due to auto-reclosing on 22.9kV distribution lines. The various factors affecting this phenomena are analyzed In detail through parametric studies. These factors Include the fault current, fault location, reclosing angle, capacitor bank size, and customer load characteristics. The impacts of these transients on customer system are described and available to identify the optimal auto-reclosing scheme.

• Proceedings of the KIEE Conference
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• summer
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• pp.397-399
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• 2004

A small-sized isolated 154kV transmission system could be brought out by a separation from whole network due to faults at transmission lines. For such system, where a fault occurs following a reclosing action, we Provided the basis for study to provide an effective load shedding scheme needed to the case of failure of reclosing action as well as the characteristic of reclosing action whether it succeeds or fails.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.106-108
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• 1996

This paper presents the Implementation and performance simulation of HSGS(High Speed Ground Switch)-Adaptive scheme for EHV transmission. EMTP/TACS(Transient Analysis of Control System) functions are combined and used for the implementation and simulation. The simulation results are compared with those for the conventional reclosing scheme and discussed.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.641-643
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• 2005

It is usual to operate the long transmission line with transposition of each phase in order to avoid voltage unbalance due to unbalanced capacitances at each phase of the line end. This paper described the Ferranti voltage rise of line end, charging current and secondary arc current according to the transposition of line or not. The positive and negative sequence current was derived by the phase current, and then the unbalanced rate was calculated. Then, we obtained the reclosing dead time of the single phase reclosing scheme for 500 kV single circuit horizontal arrangement transmission line system.

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1130-1132
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• 1999

This paper presents the feature extraction of fault current related to the multi-shot reclosing scheme in the power distribution system. Fourier transform is used to extract the feature of the fault current waveform in the case of the temporary fault and the permanent fault. After the waveform is analyzed using Fourier transform, the magnitude spectrum and the relative variation of THD are calculated. These results are that the relative variation of THD is great in the temporary fault and is little in the permanent fault.

• Proceedings of the KIEE Conference
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• 2004.11b
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• pp.36-38
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• 2004

In many countries, including Korea, in order to transmit the more electric power, the higher transmission line voltage is inevitable. So, a rapid reclosing scheme is important for UHV transmission lines to ensure requirements for high reliability of main lines. But, because of the high voltage and long span of UHV lines, the secondary arc current flows across the fault point even after the interruption of the fault current. i.e. A critical aspect of reclosing operation is the extinction of the secondary arc since it must extinguish before successful reclosure can occur. In Korea transmission lines, it is scheduled to energize 765kV single transmission line(79km) between Sin-Ansung S/S and Sin-Gapyeong S/S at June 2006. Therefore this paper analyzes characteristics of the secondary arc extinction on 765kV single transmission line using EMTP. Simulation results shows that the average value of the secondary arc is $30A_{rms}$ and the auto-extinction time of it is longer at closer point to Sin-Gapyeong S/S.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.5
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• pp.280-286
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• 2006

The paper proposes a new protection algorithm for reliable operation of grid-interfaced PV system, which can flexibly interact with conventional protective schemes of power utility grid not only to prevent damages to utility or public persons and utility apparatus caused by malfunction or failure in distribution network protection system, but also to protect a PV system itself from faults or abnormal conditions of the network. The proposed algorithm is based on reclosing characteristics of the distribution system. As a network fault occurs, the new scheme determines whether it is momentary or permanent and responds in a pre-programmed way to the fault. For permanent outage, the proposed algorithm shuts down inverter's operations but monitoring system voltage and frequency at the point of common coupling with grid. When it comes to the momentary outage, Inverter starts stand-by operation mode so that it can be automatically connected to the grid without start-up procedures as soon as the system voltage and frequency returns into the normal operation range. In order to investigate' and evaluate the PV system operation, simulation study based on PSCAD/EMTDC has been carried out to verify the performance of the proposed protection scheme.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.456-458
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• 2005

송전선로에서 발생하는 고장은 낙뢰나 수목접지로 인한 순간 고장이 대다수를 차지한다. 따라서 송전선로 보호 기능에 있어서 재폐로 기능은 계통의 안정성 향상과 공급 신뢰도의 제고를 위해서 중요한 역할을 담당한다. 본 논문에서는 154kV 송전선로 보호에 널리 사용되고 있는 디지털 방향비교 보호방식(Directional Comparison Blocking Scheme)에서 보호 구간 내부에 고장이 진전되어 발생했을 때, 재폐로 기능의 동작 특성에 대한 성능 검증 방안에 대해서 기술한다.

• Journal of Electrical Engineering and Technology
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• v.1 no.1
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• pp.8-15
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• 2006

Since the power swing depends on the operating time of the relay, the swing's magnitude can be reduced by an autoreclosure relaying system with an optimal reclosing algorithm. This paper proposes a method for stability improvement using optimal reclosure relaying. An optimal reclosure algorithm is applied to identify both temporary and permanent faults, and to predict system stability by applying WAM and high speed communication technology. It provides optimal control by predicting and determining the degree of stability, considering the real time transient stability using EEEAC. For temporary faults, the algorithm determines the system's stability and either recloses optimally for stable systems, or inserts series capacitance before optimal reclosure for unstable systems. It also applies an optimal reclosure algorithm to minimize shock and damage to the power system when reclosure fails due to permanent faults.