• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 C
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• pp.1114-1117
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• 1998

Recent applications of neural networks to power system fault diagnosis have provided positive results and have shown advantages in process speed over conventional approaches. This paper describes the application of neural network to fault detection and classification in distribution lines using the fundamental component, 2-5th harmonics index, even and odd harmonics index, and zero phase current. The Electromagnetic Transients Program (EMTP) is used to obtain fault patterns for the training and testing of neural networks. The proposed fault detection and classification method in distribution lines is obtained by analysing the difference among normal, HIF, ground fault, short circuit fault condition.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 춘계학술대회 논문집 전기설비전문위원
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• pp.35-36
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• 2007

We investigated the characteristics of three phase flux-lock type SFCL. Three phase flux-lock type consists of three reactor wound on an iron core in each single phase and the secondary coil is connected to the superconducting elements in series. the superconducting elements with serial connection were quenched simultangously in the single line-to-ground fault.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 C
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• pp.1369-1372
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• 1999

We investigated the current limiting characteristics of resistive and inductive SFCLs with 100${\Omega}$ of Quench impedance for a double line-to-ground fault, in the 154 kV transmission system. The fault simulation at the phase angles $0^{\circ}$, $45^{\circ}$, and $90^{\circ}$ showed that the resistive SFCL limited the fault current less than 17 kA without any DC component after one half cycle from the instant of the fault. On the other hand, the inductive SFCL suppressed the current below 12 kA, but with 3$\sim$5 kA of DC component which decreased to zero in 6 cycles. We concluded that the inductive SFCL had higher performance in current limiting but the resistive SFCL was better from the view point of DC components.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.255-258
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• 1999

We investigated the current limiting characteristics of resistive and inductive SFCLs with 100 $\Omega$ of quench impedance for a single line-to-ground fault. which accounts for about 70% of the total power line faults, in the 154 kV transmission system. The fault simulation at the phase angles 0$^{\circ}$, 45$^{\circ}$, and 90$^{\circ}$ showed that the resistive SFCL limited the fault current less than 15 kA without any DC component after one half cycle from the instant of the fault. On the other hand, the inductive SFCL suppressed the current below 12 KA, but with 3 kA of DC component which decreased to zero in 5 cycles. We concluded that the inductive SFCL had higher performance in current limiting but the resistive SFCL was better from the view point of DC components.

• 전기학회논문지
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• 제58권7호
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• pp.1313-1320
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• 2009

This paper analyzes the steady-state operating characteristics of doubly-fed induction generator(DFIG) and fixed-speed induction generator(FSIG) in wind turbine system. It also presents a modeling and simulation of a grid-connected wind turbine generation system for dynamics analysis on MATLAB/Simulink, and compares the responses between DFIG and FSIG wind turbine systems with respect to wind speed variation, 3-phase fault and 1-phase ground fault of the network. Simulation results show the variations of generator's active/reactive output, rotor speed, terminal voltage, fault current, etc. Case studies demonstrate that DFIG illustrates better performance compared to FSIG.

• 전기학회논문지
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• 제64권1호
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• pp.182-187
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• 2015

In the three-phase power system, when any one-phase or two-phases is open-phase, the unbalanced current flows and the single-phase power supplies to three-phase loads. Specially, motor coil and transformer coil receive over-current. As a result, great damage as well as electrical fire can occur to the power system. In order to improve these problems, this paper proposes that an open-phase detection device is designed by a new algorithm using electric potential difference between the resultant voltage of neutral point and ground, and a control circuit topology of open-phase protector is composed of highly efficient semiconductor devices. It improves response speed and reliability. The control algorithm circuit also operates the cut-off of a conventional residual current protective device (RCD) which flows an enforced leakage current to ground wire at open-phase accident. Furthermore, time delay circuit is added to prevent the incapable operation of open-phase protector about instantaneous open-phase not open-phase fault. The time delay circuit improves more reliability.

• Transactions on Electrical and Electronic Materials
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• 제15권3호
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• pp.117-124
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• 2014

The calculation of short-circuit currents is important for power systems operation and restoration, and for determining the means to protect human lives and properties. In this paper, a part of a power system network, around the D$\breve{e}$tmarovice power station in Czech Republic, was simulated by the well known program EMTP-ATPDraw (Electromagnetic Transients Program-Alternative Transient Program), and short-circuit currents and voltages were calculated at different points in the electric network and presented as a time function by the PlotXY program. Calculations were done just for phase-to-ground, and for the three-phase short-circuit at the Kun$\check{c}$ice substation. The results were important for determining the characteristics of the equipment required to withstand or break the short-circuit current; for this reason, the calculations were repeated using earth-fault resistances only for the case of busbar KUN shown in Figs. 5 and 6.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
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• pp.236-238
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• 1999

This paper presents a model and analysis results of 3 phase utility interactive photovoltaic power generation system. The control system is composed of feed forward, feedback and PID system. The voltage source inverter system provides sinusoidal PWM at current for the loads of utility system. A phase to ground fault and 3 phase fault are analyzed, and the results are discussed.

• 전기학회논문지
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• 제56권7호
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• pp.1183-1190
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• 2007

This paper proposes the improved fault decision algorithm using DWT(Discrete Wavelet Transform) and ANNs for the FRTU(Feeder Remote Terminal Unit) on the feeder in the power distribution system. Generally, the FRTU has the fault decision scheme detecting the phase fault, the ground fault. Especially FRTU has the function for 2000ms. This function doesn't operate FI(Fault Indicator) for the Inrush current generated in switching time. But it has a defect making it impossible for the FI to be operated from the real fault current in inrush restraint time. In such a case, we can not find the fault zone from FI information. Accordingly, the improved fault recognition algorithm is needed to solve this problem. The DWT analysis gives the frequency and time-scale information. The neural network system as a fault recognition was trained to distinguish the inrush current from the fault status by a gradient descent method. In this paper, fault recognition algorithm is improved by using voltage monitoring system, DWT and neural network. All of the data were measured in actual 22.9kV power distribution system.

• 한국전자통신학회논문지
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• 제17권6호
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• pp.1113-1120
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• 2022

본 논문에서는 스마트 그리드 배전 시스템이 요구하는 디지털 FRTU(: Feeder Remote Terminal Unit)를 위한 통신 방법론을 연구하였다. 디지털 FRTU는 고장처리부와 통신부로 구성하는데, 고장처리부는 고장 시 고장정보를 통신부로 전송하며, 통신부는 주변 디지털 FRTU간 양방향 통신을 통해서 고장구간을 자율적으로 판별할 수 있도록 설계하였다. 성능 검증을 위해서 다양한 고장 시나리오들에 대한 고장모의가 가능하도록 3개의 디지털 FRTU를 기반으로 3개의 선로구간을 구성하는 하나의 성능 검증 시스템을 구축하였다. 구축된 성능 검증 시스템 상에서 1선 지락고장, 선간 및 3상 단락고장을 포함하는 다양한 고장 경우들을 실험적으로 모의하였으며, 각 경우에서 정확한 추론결과를 검증으로써 개발된 방법론의 유효성을 확인할 수 있었다.