• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.531-532
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• 2011

This paper describes the characteristics analysis of power-optical fiber composite cable on underground transmission lines. The effects on grounding, air gap and contact resistance are variously analysed using EMTP in normal operating condition. From these results, in this paper, the scheme for protecting the electrically abnormal phenomena will be established on power-optical fiber composite cable of underground transmission lines.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.8
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• pp.410-417
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• 2005

This paper analyses the transient phenomena against single line to ground fault and lightning surge on underground power cable systems. For analysis in various fault conditions, several actual underground power cable systems are modeled using ATP In ground fault, the transient characteristic of the conductor and the sheath according to the fault current and the installation types of CCPU are analysed. In lightning surge strokes, the various unbalanced conditions including the length of crossbonded lead, the breakdown of CCPU and distance unbalance are considered. This paper is expected to contribute the establishment of proper protection methods against transients on underground power cable systems.

• Journal of Power Electronics
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• v.18 no.4
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• pp.997-1006
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• 2018

This paper proposes a transformerless photovoltaic (PV) power converter system based on the DC/AC boost inverter, which can solve the leakage current and second-order ripple power issues in single-phase grid-connected PV inverters. In the proposed topology, the leakage current can be decreased remarkably since most of the common-mode currents flow through the output capacitor, by-passing parasitic capacitors, and grounding resistors. In addition, the inherent ripple power component in the single-phase grid inverter can be suppressed without adding any extra components. Therefore, bulky electrolytic capacitors can be replaced by small film capacitors. The effectiveness of the proposed topology has been verified by simulation and experimental results for a 1-kW PV PCS.

• Proceedings of the KIEE Conference
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• 2003.10a
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• pp.233-235
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• 2003

To obtain a low ground resistance in high resistivity soil or in insufficient place such as downtown, long vertical ground rods are often used. However, if the lightning current or fault current with high frequency flows into the grounding system, the ground impedance is significantly increased. This paper presents how the impulse current works on the long vertical ground rods with a different length. As a result, it can be estimated what the waveform is composed of and how the GPR is affected by the rate of current change.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.654_655
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• 2009

접지의 실시목적은 감전 및 전위상승에 따른 전기위험으로 인체를 보호하고 전기, 전자, 통신기기등이 외, 내부 surge 발생 시 기기를 보호하여 안전하게 사용하기 위한 것이다. 접지방법은 이전에는 접지극 설치에 의하여 단순히 접지저항을 측정하여 접지저항값이 기준치에 적합하면 접지가 올바르게 실시된 것으로 간주하였으나 현재는 전자 기기 및 통신기기등의 발달로 인하여 전자부품이 noise에 취약하기 때문에 복잡하고 체계적인 접지시스템 설계의 필요성이 대두되었다, 이에 따라 본 논문에서는 접지시스템의 설계방법, 설계시 고려요소, IEEE,IEC의 규격에서의 접지설계방법등에 대하여 고찰하였다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.10
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• pp.1811-1816
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• 2011

This paper describes switching surge analysis for reclosing decision in 345kV combined transmission line with GIL. Reclosing operation should be decided based on the detailed technical analysis in combined transmission line because this line includes power cable section which is week on insulation. Insulation of power cable can be breakdown at the week point in case of reclosing moment. Therefore the detailed analysis has to be carried out by considering several conditions such as charging rate, inserting resistance, arrester, length ratio of power cable section, grounding resistance, etc. Analysis is performed by EMTP/ATP.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.2190_2192
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• 2009

풍력발전기술은 무한정의 천연 무공해 에너지원을 개발하는 기술로써 환경에 미치는 영향이 없고 산업적 가치와 국토 이용 효율을 높일 수 있는 사회적 가치가 높은 기술이다. 이러한 풍력설비는 특성상 산간이나 제방과 같은 낙뢰 환경에 노출되기 쉽고 기존의 전력계통과도 연계되어 운용됨으로 지락이나 서지와 같은 위험으로부터 설비의 안전과 보호가 필요하다. 본 논문에서는 다수의 풍력발전설비에 대한 접지시스템의 설계 방안과 접지시스템구성에 대해 연구하였다. 또한 풍력 발전 설비와 인명의 보호를 위한 접지시스템 구축 제안과 접지성능을 안정적으로 얻는 공통접지구성에 대해 연구하였고, 현장의 대지저항률를 실측 분석하여 반영된 접지설계 및 시공을 통해 접지성능을 확인하였다.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.446-448
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• 2000

This paper discribes the modeling and transient analysis of cable in combined transmission line under high impedance fault(HIF). And also, transient characterstic analyzed on cable covering protection unit(CCPU) is presented. Modeling of the combined transmission line is established in PSCAD/EMTDC V3. The required data to analyze the transient phenomena is given from the actual system. The results show the HIF modeling in cable, fault current according to the value of fault resistance. And also when the value and method of grounding resistance is changed in CCPU, simulation results are presented.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.298-299
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• 2006

This paper analyzes operation sensitivity of a relay, a blind spot of differential protection relaying, and how to protect the blind spot in protective relying of $3{\Phi}$ Y-Delta transformer consisting of three $1{\Phi}$ transformers which Korean pumped storage power plants have been using. Each different protective relayings must be adopted because there are differences between $3{\Phi}$ trans-former and $3{\Phi}$ transformer consisting of three $1{\Phi}$ trans formers. Also, in the system using high resistance grounding for fault current restriction of delta side, protection for delta side faults have to be considered properly.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.140-142
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• 2005

This paper describes the current- based compact digital motor protective relay for low and high voltage induction motors, which are widely used in industrial and commercial power systems. The existing protective relays for motor protection had only overload, short circuit, reverse phase, open circuit and grounding protective elements, and measurement, start/stop control function. But in present day, for automation system, various functions are required, especially motor management and sequence control function and more. To meet these requirements, we developed an economic current-based compact digital motor protective relay which had various function to control, manage and monitor the induction motor.