• Journal of Electrical Engineering and Technology
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• v.8 no.6
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• pp.1400-1408
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• 2013

This paper proposes a new grid-tied power converter for battery energy storage, which is composed of a 2-stage DC-DC converter and a PWM inverter. The 2-stage DC-DC converter is composed of an LLC resonant converter connected in cascade with a 2-quadrant hybrid-switching chopper. The LLC resonant converter operates in constant duty ratio, while the 2-quadrant hybrid-switching chopper operates in variable duty ratio for voltage regulation. The operation of proposed system was verified through computer simulations. Based on computer simulations, a hardware prototype was built and tested to confirm the technical feasibility of proposed system. The proposed system could have relatively higher efficiency and smaller size than the existing system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.8
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• pp.67-74
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• 2013

Major utilities have been focusing on R&D and nationwide business of AMI system which plays a vital role in SmartGrid whose concept is to maximize energy efficiency and optimize electric power facility management with exchanging real time information between utilities and consumers based on ICT technologies in power grid. In this paper, we suggest a power loss monitoring method using KEPCO's AMI system which is operating in fields and with the acquisition of AMI data and analyses verify the validation of a power loss monitoring method.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.31-33
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• 1999

In this paper, a operating characteristics of the 50 kW grid-connected Photovoltaic(PV) Power system which is by means of initial PV datum analyzing is reported. The development of a 50 kW class photovoltaic power generation system including a DC/AC inverter is suggested to investigate the system performance for grid connection. The results of the demonstration test of a 50 kW class grid-connected PV system show that the system utilization rate is 15.6% and the inverter efficiency is 94% at 80% load.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1171-1173
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• 2000

This paper was analyzed the high-frequency harmonics, power conversion rate, results of the system's monitor, and measuring data of the system power output of a 3-phase photovoltaic power system for grid-connection. The photovoltaic power system consists of a 3-phase inverter array, and data acquisition system. The result of an analyzing data of the 50 kW class grid-connected photovoltaic system showed the stable behavior in utility-interactive operation.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.10a
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• pp.291-293
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• 2003

Applicability and economical feasibility of a Superconducting Fault Current Limiter (SFCL) have been investigated using the PSS/E simulation for a bus bar coupling at the real 154 ㎸ KEPCO power grid near Seoul. For the investigated substation, the maximum fault current exceeds the interruption rating of 4 circuit breakers (CB) out of 9 installed in the substation. The simulation showed that a SFCL installed in the bus tie position effectively limits the fault currents to save 4 CBs, which are to be replaced by ones of gloater interruption rating, otherwise. We suggest that the optimum resistance of the SFCL be 10 Ohm for the given grid.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.41-42
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• 2015

도시에서의 에너지는 주로 인력에 의해 관리되고 소비된다. 전력이나 물, 가스 등 살아가는데 필요한 에너지는 화석연료로 생산되거나 만들어진다. 따라서 전력 등과 같은 에너지의 소비가 많을수록 이산화탄소 배출이나 지구온난화가 심화된다. 도시의 건축물에 대한 에너지의 공급체계는 건축물과 별도로 구성되어 있어 통합적 관리를 통해 사용량을 최적화하여야 한다. 본 논문에서는 스마트그리드 스테이션을 기반으로 한 스마트그리드 시티를 구축하는 방안을 제시하고자 한다. 이를 통해 홈, 타운, 시티를 거쳐 최종적으로 스마트 에너지 국가를 완성하게 된다.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.204-205
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• 2007

본 고에서는 태양광 발전용 전력변환장치의 국산화 개발에 성공하여 적용한 120kW급 특고압 연계형 태양광 발전시스템의 구성 및 발전특성에 대하여 기술하고자 한다. 본 설비는 2005년 8월 25일부터 한국서부발전(주) 태안발전본부에서 운전 중이며 현재까지 특별한 문제점 없이 정상적으로 운전되고 있다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.1
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• pp.55-62
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• 2016

Nuclear fuels are always exposed to hot temperature and high speed coolant flow during the reactor operation. Thus the fuel rod accompanies small amplitude vibration due to the turbulent flow. The random vibration causes friction between the fuel rod and the grid structure which provides the lateral supports. The friction is critical to the fuel rod fretting wear, and it degrades fuel performance when a severe wear is developed. LuGre friction model is introduced in the paper, and the performance was evaluated comparing to the classical Coulomb model. It is shown that the developed friction force considering the Coulomb friction is not enough to stop or delay the motion while the stick-slip can be simulated using LuGre friction model. Numerical solutions of the two dimensional spacer grid cell model with the modern friction are also reviewed, and it is discussed that the new friction model simulates well the nonlinear mechanism.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.1
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• pp.115-119
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• 2016

For many past years, research in the operation of stand-alone Microgrid, which provides electric power generated from renewable energy sources and energy storage system instead of diesel generators, has been a major issue in order to prepare the exhaustion of fossil fuel and to protect environment, in island grids. Samso Island, known as the world's first stand-alone Microgrid in Denmark, is connected to the mainland grid through AC system, which has different technical conditions with Korea's isolated power system. Korea's first stand-alone Microgrid has been built in Ga-sa island, Chun-la-nam-do, based on Energy Management System (EMS) operation, and other islands are under construction to follow the next step. These stand-alone Microgrid's has large capacity of Battery Energy Storage System (BESS) and the proportion of the renewable energy sources are large, which makes it necessary to use a Microgrid-Energy Management System (MG-EMS) to operate the grid effectively and economically. However, since the main subject of MG-EMS is different from EMS, specific characteristics and functions must be different as well. In this paper, the necessary characteristics and functions are explained for a general MG-EMS compared to a large power system EMS.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.228-229
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• 2011

스마트 그리드(Smart Grid)는 기존 전력망에 IT기술을 융합하여 전력회사와 고객들 간의 실시간으로 양방향 정보 교환을 수행하는 시스템으로, 고객에게 전기 사용량 정보를 제공하는 서비스를 통해 전기의 사용량을 절약하도록 유도하는 것이 주요 목적인 차세대 전력망 시스템이다. 본 논문은 현재 개발 중인 AMI 요소 기술들의 상호 연동 테스트 방안을 소개하고 세부 구간 및 전구간 테스트 수행을 통해 얻은 각 시스템들의 로그 및 시스템별 응답 결과를 토대로 개발 기능의 적정성을 검증한다.