• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.3
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• pp.228-236
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• 2022

The charging methods of electric vehicles are divided into wired charging and wireless charging. Restrictions on the use of charging infrastructure for wireless charging vehicles currently exist because most charging infrastructure uses the wired charging method. Thus, wired and wireless integrated charging system has been studied. In this system, a wireless charging system especially requires a control method for high-efficiency operation in consideration of a change in a coupling coefficient. Therefore, this paper introduces two control methods for the high-efficiency operation of wireless charging that can be applied to wired and wireless integrated charging systems. In addition, loss analysis is performed through PSIM simulation to select a more advantageous method for high-efficiency operation among the two control methods. To verify the simulation-based loss analysis result, the two control methods are applied to the actual wireless charging system, and the efficiency is compared through the experiments Based on the experimental results, a control method suitable for high-efficiency operation of the wireless charging method is selected.

• Journal of Information Processing Systems
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• v.14 no.5
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• pp.1136-1149
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• 2018

With the increasing of urban electricity demand, making the most use of the power cable carrying capacity has become an important task in power grid system. Contrary to the rated ampacity obtained under extremely conservative conditions, this paper presents the various steady value of cable ampacity by using the changing surrounding parameters under operation, which is based on cable ampacity calculation equation under the IEC-60287 standard. To some degree, the cable ampacity analysis of actual surroundings improves the transmission capacity of cables. This paper reveals the factors that influence cable ampacity such as insulating layer thickness, allowable long-term conductor temperature, the ambient temperature, soil thermal resistance coefficient, and so on, then gives the class of the influence of these parameters on the ampacity, which plays a great role in accurately calculating the real-time ampacity and improving the utilization rate of cable in the complex external environment condition. Furthermore, the transient thermal rating of the cable is analyzed in this paper, and temperature variation of the conductor under different overload conditions is discussed, which provides effective information for the operation and control of the system.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.11
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• pp.532-537
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• 2006

Lightning induced faults accounts for more than 66% at the transmission lines of KEPCO. The lightning causes damages to power system equipments including transmission line, the blackout of electricity and the electro-magnetic interference. Because of this reason, we need the real time lightning information for the optimal operation of power system. And, it is required to obtain and accumulate the lightning current parameters for the insulation design. In 2005, KEPRI constructed a lightning detection network, the KLDNet (i.e. Kepco Lightning Detection & Information System) and launched a lightning information service for KEPCO customers. It is intended to provide data service on the operation of transmission lines and collect lightning-related data, which is the most important factor regulating power system design and operation. The new system will replace LPATS, the old detection system, which has been operating since 1995 and is rapidly failing in terms of both detection performance and location accuracy. The purpose of this paper is to explain the work performed and the results of that work in performing a site survey of several locations. The purpose of the site survey is to find locations acceptable for the installation of a lightning location receiver in support of a Lightning detection system(LDS). A restriction was placed on the surveyed locations, as they must belong to the Korea Electric Power Company. This requirement was made to facilitate the communication needs of the LDS network. Total of 15 sites were evaluated as possible LDS sensor sites. Some of the sites were rejected for physical reasons and therefore no electrical testing was performed. Of the 15 sites, total of 10 sites were considered acceptable and 5 sites were rejected for various reason. In this paper, we would like to explain the site survey and detection efficiency for LDS.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.1
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• pp.38-45
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• 2021

The photovoltaic module has the characteristic of changing its output characteristics depending on the amount of radiation and temperature, where the arrays that connect them in series and parallel also have the same characteristics. These characteristics require the MPPT technique to find the maximum power point. Existing P&O and IncCond cannot find the global maximum power point (GMPP) for partial shading. Moreover, in the case of Improved-GMPPT and Enhanced Search-Skip-Judge-GMPPT, GMPP due to partial shading can be found, but the variation in the open voltage during temperature fluctuations will affect the operation of the Skip and will not be able to perform accurate MPPT operation. In this study, we analyzed the correlation between voltage, current, and power under solar module and array conditions. We also proposed a technique to find the maximum power point even for temperature fluctuations using not only the amount of radiation but also the temperature coefficient. The proposed control technique was verified through simulations and experiments by constructing a 2.5 kW single-phase solar power generation system.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1335-1337
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• 2002

This paper presents experimental operation with utility interactive 50kw photovoltaic generation system. And that describe configuration of utility interactive photovoltaic system which power supply for dormitory. The status of photovoltaic generation system components and interconnection and safety equipment will be summarized. This paper discusses property operation state which system endure division of power for dormitory.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.144-146
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• 2004

This paper presents experimental operation with utility invertactive 3kW photovoltaic generation system. And that describe configuration of utility interactive photovoltaic system which power supply for Demonstration experiment. The status of photovoltaic generation system comp-onents and interconnection and safety equipment will be summarized. This paper discusses property operation state which system endure division of power for demonstration experiment.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.321-322
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• 2006

Faults on power systems are inevitable phenomena. These faults can be classified by two categories, temporary and permanent faults. Without distinction of fault types, the faults would induce several changes on power system such as transmission line trip. Especially, the most common phenomena which loads experience by the power system fault is voltage sag. Voltage sags mean that the bus voltage maintains under 0.9 p.u. of rating for several cycles, and they give serious effects to operation of load devices. To ensure proper operation of the load, the flywheel systems, one of the energy storage system, are suggested in this paper. This paper demonstrates the efficiency of flywheel energy storage system against voltage sag by PSCAD/EMTDC simulation.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.663-666
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• 1999

This paper describes a three-phase converter with high power factor using a scheme of discontinuous current mode(DCM). The proposed system can replace the conventional diode bridge with step-up chopper which is used as a converter for adjustable speed drive. In this system, the current of reactor is zero at turn-on instance because of operation in DCM, while the switch turns off at the instance of maximum current. A soft-switching scheme with lossless snubber was proposed. Therefore, a zero-voltage switching at turn off can be achived by lossless snubber and zero-current switching at turn on can be obtained by operating under DCM. A theoretical analysis and computer simulations with PSpice were done to verify the operation of the proposed system. Also a prototype of hardware system was built and tested for verifying the feasibility of proposed system.

• Proceedings of the KIEE Conference
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• 1992.07a
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• pp.85-88
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• 1992

This paper describes the need of the Database which is designed built with data lot a highly Integrated system for power system planning and operation. The study also, deals plans for and designs of thr highly integrated systems in order to optimize coordination of security and economy of power system planning and operations, as well as to improve the efficiency of data handling

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.564-566
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• 2006

This paper presents experimental operation with utility interactive 50kW photovoltaic generation system. And that describe configuration of utility interactive photovoltaic system which power supply for dormitory. The status of photovoltaic generation system components and interconnection and safety equipment will be summarized. This paper discusses property operation state which system endure division of power for dormitory.