• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.47-55
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• 2015

This paper proposes the installation of a new modular multilevel converter based high-voltage direct current (MMC-HVDC) system to connect between mainland and Jeju island power systems in Korea in 2020. The purpose is to combine with two old line-commutated converters (LCC)-based HVDC system to achieve a stability of the Jeju island power system. The operation of the overall system will be analyzed in three cases: (i) wind speed is variable, (ii) either one of the LCC-HVDC systems is shutdown because of a fault or overhaul, (iii) a short circuit fault occurs at the mainland side. The effectiveness of the proposed control method is confirmed by the simulation results based on a PSCAD/EMTDC simulation program.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.10a
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• pp.205-208
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• 2003

Maximum short circuit current of modern power system is becoming so large that the current should transmission capability. Although there are various kinds of method to solve this, approached from super conductivity Fault Current Limiter application viewpoint among them. High Temperature Superconductor-Fault Current Limiter (HTS-FCL) development is progressing according to HTS technology development, and system application is tried. For actual system application of such super conductivity FCL, an efficient method to find FCL locations suitable for reduction of short circuit currents of more than one fault location is developed.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.321-323
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• 2003

Maximum short circuit current of modern power system is becoming so large that the current should transmission capability. Although there are various kinds of method to solve this, approached from super conductivity Fault Current Limiter application viewpoint among them. High Temperature Superconductor-Fault Current Limiter(HTS-FCL) development is progressing according to HTS technology development, and system application is tried. For actual system application of such super conductivity FCL, an efficient method to find FCL locations suitable for reduction of short circuit currents of more than one fault location is developed.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2003.11a
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• pp.111-116
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• 2003

Recently, power-electronics equipments or machine that microprocessor is included and computers have been installed continuously in industrial process or region of electronics customer. So concern for power quality, especially sags has been increased. Because those equipments are very sensitive to sags. The sag is phenomenon that magnitude of load voltage temporarily decreases because of power system fault. If a certain equipment in industrial process have any trouble result from sag, it can cause utility to be charged for enormous economics loss. Therefore it need to analyze the characteristic of sag and then mitigation method for sags in distribution system in oder to increase reliability. This paper gives an overview of sags characteristic due to short circuit fault in distribution system and after a general discussion of the various forms mitigation, gives a sags mitigation method with concentrating on mitigation-device interface method, especially FCL that is Fault Current Limiter.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.983-989
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• 2015

Power transformer is one of the major and key apparatus in electric power system. Monitoring and diagnosis of transformer fault is necessary for improving the life period of transformer. The failures caused by short circuits are one of the causes of transformer outages. The short circuit currents induce excessive forces in the transformer windings which result in winding deformation affecting the mechanical and electrical characteristics of the winding. In the present work, a transformer producing only the radial flux under short circuit is considered. The corresponding axial displacement profile of the windings is computed using Finite Element Method based transient structural analysis and thus obtained displacements are compared with the experimental result. The change in inter disc capacitance and mutual inductance of the deformed windings due to different short circuit currents are computed using Finite Element Method based field analyses and the corresponding Sweep Frequency Responses are computed using the modified electrical equivalent circuit. From the change in the first resonant frequency, the winding movement can be quantified which will be useful for estimating the mechanical withstand capability of the winding for different short circuit currents in the design stage itself.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.2
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• pp.100-105
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• 2022

This paper applies the arc detection algorithm to prevent the false detection in photo voltaic series arc detection circuit, which is required not only to detect the series arc quickly, but also not falsely detect the arc for the non-arc noise. For this purpose, this study proposes a rapid and preventive false detection method of single peak noise and short noise signals. First, to prevent false detection by single peak noise, Discrete wavelet transform (DWT)-based characteristic parameters are applied to determine the shape and the amplitude of the noise. In addition, arc fault detection within a few milliseconds is performed with the DWT iterative algorithm to quickly prevent false detection for short noise signals, considering the continuity of serial arc noise. Thus, the method operates not only to detect series arc, but also to avoid false arc detection for peak and short noises. The proposed algorithm is applied to real-time serial arc detection circuit based on the TMS320F28335 DSP. The serial arc detection and peak noise filtering performances are verified in the built simulated arc test facility. Furthermore, the filtering performance of short noise generated through DC switch operation is confirmed.

• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.476-478
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• 2001

Coordination under short-circuit conditions is a systematic application of protective devices in the electrical power system, which, in response to a fault, will remove only a minimum amount of equipment from service. The objective is not only to minimize the equipment damage and process outage costs, but also to protect personnel from the effects of these failures. The coordination study of an electric power system consists of an organizes time-current study of all devices in series from the utilization device to the source. This study is a comparison of the time it takes the individual devices to operate when certain levels of normal or abnormal current pass through the protective devices. The objective of a coordination study is to determine the characteristics, ratings, and settings of overcurrent protective devices that will ensure that the minimum unfaulted load is interrupted when the protective devices isolate a fault or overload anywhere in the system. At the same time, the devices and settings selected should provide satisfactory protection against overloads on the equipment and interrupt short-circuit as rapidly as possible.

• Journal of Electrical Engineering and Technology
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• v.9 no.1
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• pp.254-258
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• 2014

This paper presents the performance analysis results of a short line fault interruption of a gas circuit breaker, particularly a self-blast type breaker. Hot gas flow analysis was carried out using a CFD calculation combined with the arc model and nozzle ablation model. To evaluate the interruption performance, the index function was defined using the pressure in the heating chamber and the density above the arc region. The simulation and test results showed that the gas flow field and suitable choice of an interruption performance index can be used to predict the interruption characteristics and provide guidelines for designing self-blast breakers with a higher interruption capability.

• KIEE International Transactions on Electrophysics and Applications
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• v.3C no.3
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• pp.73-76
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• 2003

In modern EHV (Extra High Voltage) class GCBs (Gas Circuit Breakers), the interruption capability for SLF (Short Line Fault) is one of the most important aspects of performance required for GCBs. Up to now, the SLF interruption capability of EHV class GCBs was partially assisted by the adoption of capacitors able to decrease the dV/dt of the TRV (Transient Recovery Voltage), particularly the TRV on the line side. This paper describes the technique to increase the SLF interruption capability of EHV class GCBs as well as the procedure to develop capacitorless l70kV 50kA GCB.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.874-875
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• 2007

This paper introduces major potential faults of IPMSM and their simulation realization methods. The faults of IPMSM, generally, contain single-phase open circuit, single-phase or 3-phase short circuit, and uncontrolled generation. When different fault occurs, the circuit of total system including motor and inverter also will be changed. Therefore, it is necessary to analyze and establish independent model for each kind of fault. In this paper, first, the drive circuit is analyzed as different fault type. Then, the corresponding simulation results solved in Simulink@MATLAB are given. The absence of experiment results leads that the veracity of simulation results can not be verified, but the tendency will be explained by theory analysis.