• 전기전자학회논문지
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• 제22권3호
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• pp.738-741
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• 2018

DC전원(신재생에너지, 직류기반 디지털기기) 및 DC부하가 늘어나면서 기존 계통에서의 불필요한 변환과정이 발생한다. 이러한 문제 때문에 최근 직류배전시스템의 관심이 증가하고 있다. 직류배전시스템이란 처음부터 DC로 전원을 공급하는 방식으로 불필요한 변환과정이 줄어들어 전력손실이 높아지게 된다. 뿐만 아니라 안정적으로 전력을 공급해주고, 전자파로부터 인체를 보호해주는 장점이 있다. 직류배전시스템의 중요도가 높아짐에 따라 직류계통의 조류해석도 필요하다. 본 논문에서는 컨버터의 제어방식에 대하여 간단하게 서술하고, DC 조류계산 방식에 대하여 서술하였다. 마지막으로 MATLAB과 DC 조류를 해석할 수 있는 툴인 ETAP의 시뮬레이션 결과를 비교하였다.

• 정보처리학회논문지D
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• 제10D권7호
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• pp.1207-1212
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• 2003

전자상거래의 발전과 함께 물류유통을 위한 분배망의 구성은 점차 복잡해지고 있으며, 이에 따라 분배계획이 점차 중요해지고 있다. 분배계획에 있어서 분배망의 관리는 중요하다. 분배망은 분배센터(DC)와 그 상호작용으로 나타낼 수 있다. DC 내부요인 및 DC의 상호작용으로 인한 외부요인은 분배망에 많은 영향을 미친다. 따라서 효율적인 분배망 관리계획의 수립을 위해서는 DC와 DC의 상호작용을 고려한 분배망의 분석이 필요하다. 지금까지 자원할당 같은 공급망 관리 관점의 연구가 이루어졌지만 공급망을 구성하는 분배망의 분석에 대한 연구가 이루어지지 않았다. 본 논문은 DC와 DC의 상호작용을 고려한 분배망 분석 기법을 제안한다. 제안 기법은 크게 두 가지 단계로 이루어진다. 먼저, 분배망은 DC와 DC의 상호작용을 포함한 그래프 형태로 모델링된다. 두 번째, 그래프로 모델링된 분배망은 도달성 트리를 이용하여 분석된다. 또한 예제모델을 제시하고, 이것의 분석을 통해 제안기법의 효용성을 보였다.

• 전력전자학회논문지
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• 제17권6호
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• pp.495-499
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• 2012

Recently, DC distribution systems become hot issues since DC type loads increase rapidly according to the expansion of IT equipment such as computers, servers, and digital devices; DC type loads will cover 50% for all electricity loads in 2020 which was mere 10% in 2000. DC distribution systems are also accelerated by the expansion of renewable power systems since they are easy to be interfaced with DC grids rather than AC grids. However, removing the fault current in DC grids is comparably difficult since the current in DC grids has non zero-crossing point like in AC grids. Thus, developing dedicated DC circuit breakers for DC grids is necessary to get safety for human and electrical facilities. Magnet arc extinguishing method is proper to small size DC circuit breakers. However, simple Magnet arc extinguishing method is not enough to break inductive fault currents. This paper proposed a novel DC circuit breaker against inductive fault current defined by IEEE C37.14-2004 Standard for Low-Voltage DC Power Circuit Breakers Used in Enclosures. The performance of the proposed DC circuit breaker was verified by an experimental circuit breaker test system built in this research.

• 전력전자학회논문지
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• 제22권4호
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• pp.353-359
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• 2017

To take advantage of electric propulsion, several large vessel kinds, namely, cruise vessels, icebreakers, drill ships, and warships, have been generally designed with Integrated Power System (IPS). Although most of these vessels have adopted AC distribution IPS, DC distribution IPS ships have recently emerged as a new promising technology thanks to the availability of the products related to the DC distribution system, in which the system's major advantages over AC distribution are reduced weight and fuel consumption. This paper presents the comparison results of a 10-t class fishing boat for the AC distribution and DC distribution cases. By replacing AC distribution system with DC distribution, 31-41% reduction in the weight of the electrical equipment weight and 20-25% reduction in the fuel consumption are expected.

• KEPCO Journal on Electric Power and Energy
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• 제5권4호
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• pp.275-286
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• 2019

본 논문은 DC (Direct Current) 배전망 혹은 DC 마이크로그리드 운영을 위한 실시간 DC 계통해석 응용프로그램의 개발에 대한 내용을 다룬다. 응용프로그램은 중앙 에너지 관리시스템(EMS: Energy Management System)에 탑재되어 운영자에게 실시간으로 운영 솔루션을 제공한다. DC 배전계통을 해석하기 위한 프로그램의 구성 및 시퀀스를 제안한다. 각 프로그램의 알고리즘과 AC 계통 프로세스와의 차이점을 분석한다. 한국전력공사 고창전력시험센터 내 DC 배전망 실증사이트를 소개하고, EMS 구축 내용을 기술한다. 개발된 DC 계통해석 응용프로그램을 실증 사이트 EMS에 탑재하여, 검증 시험을 수행한다. DC 배전망 전압 제어를 위한 시험 시나리오를 구성에 대해 논한다. 마지막으로 실증시험 결과 측정 데이터, 응용프로그램 결과 데이터를 PSCAD/EMTDC를 이용한 오프라인 시뮬레이션 결과값과 비교 분석하여 정합성을 검증한다.

• 전력전자학회논문지
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• 제20권3호
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• pp.209-213
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• 2015

With the increasing popularity of renewable generation systems and the advancement of power electronics, DC distribution systems have recently received considerable research attention. DC distribution has numerous advantages, including reliability, power quality, and efficiency. Owing to these advantages, DC distribution has been applied to data centers and power quality-sensitive electronic load conditions. Because grounding electrodes in DC are much more susceptible to corrosion than in AC, the IT system defined in IEC Standard 60364 may be a good candidate for an earthing method for DC distribution systems. In addition, IEC Standard 61557 specifies the requirements for insulation monitoring devices (IMD) for protection of the IT system, which continuously monitors the insulation resistances between the power lines and the earth. This paper discusses the development and evaluation of IMD to promote the reliability of distribution systems and increase safety of humans and facilities.

• 전력전자학회논문지
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• 제17권1호
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• pp.21-26
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• 2012

In recent years, DC distribution systems are becoming hot issue due to the increase in digital loads and DC generation systems according to the expansion of renewable energy technologies. However, removing the fault current in DC grids is comparably difficult since the current in DC grids has no zero-crossing point like in AC grids. Thus, developing dedicated DC circuit breakers for DC grids is necessary to get safety for people and electrical facilities. This paper proposes magnet arc extinguishing method to develop a 300[$V_{DC}$]/10[A] DC circuit breaker. The performance of the proposed DC circuit breaker was verified by an experimental circuit breaker test system built in this research.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.486-487
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• 2011

In this paper, a configurable DC distributiong system is being proposed considering national power systems conditions and a comparative analysis of the transient response of the contingencies is performed with the conventional AC systems. DC systems are evaluated as a promising next-generation distribution system that provides reliable operation through high efficiency of energy use and converter control. This paper discusses about the required elements for the national DC distribution system and has analysed the fault characteristics of the AC and DC distribution systems using PSCAD/EMTDC. According to the simulation results, the DC system has improved response, due to the DC/DC converter's charging/discharging characteristics, in terms of voltage and power system characteristics when compared to AC systems.

• 조명전기설비학회논문지
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• 제29권6호
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• pp.42-48
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• 2015

DC distribution system is difficult to compose the single-system because of the capacity restriction of power semiconductors. Therefore, DC Distribution system needs parallel operation of AC/DC converters for increase to system capacity. However, this system generates the circulating current. This paper is reducing the circulating current and safely sharing the load using the proposed DC current droop control method when each other 3-phase AC/DC converter connected. This system confirms through the simulation and experiment. Also, when each other converter of parallel operate. it is compared the response characteristics

• Journal of Electrical Engineering and Technology
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• 제9권3호
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• pp.812-819
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• 2014

The proposed technical work attempts to compare the two key technologies of power distribution, i.e. direct current (DC) and alternating current (AC) in a fiscal manner. The DC versus AC debate has been around since the earliest days of electric power. Here, at least four types of a low voltage DC (LVDC) distribution are examined as an alternative to the existing medium voltage AC (MVAC) distribution with an economic assessment technique for a project investment. Besides, the sensitivity analysis will be incorporated in the overall economic analysis model to cover uncertainties of the input data. A detailed feasibility study indicates that many of the common benefits claimed for an LVDC distribution will continue to grow more profoundly as it is foreseen to arise with the increased integration of renewable energy sources and the proliferation of energy storage associated with the enhanced utilization of uninterruptible power supply (UPS) systems.