• Journal of Power Electronics
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• 제2권2호
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• pp.124-129
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• 2002

Invertigation electromagnetic emissione of inverter power sources resistance welding existing special aspects of EMI measurements in the field of resistance welding machines resulting from the power rating and operation mode of these machines have to be taken into account. The characteristics of the internal switching processes determined by the behavior of the applied power semiconductors, sunbber circuits and constructional aspect exert a great influence on the conducted emission welding inverters.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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• pp.603-605
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• 2006

To reduce inference of any power delivery failures in underground power cable, power system operators are trying to find effective way of finding fault location as soon as possible. But it is very difficult to find fault location exactly for underground power cable. We are developing fault location system for underground power cable which can detect its fault location exactly. This new system monitors current and voltage of underground power cable by using low voltage and current sensors and if there are any accidents, it records its transient signal. Fault location is calculated by analyzing recorded signal. To develop fault location system for power cable, we needed fault simulation system and we installed it physically and tested. In this rapers, we describe on describe of fault location system for underground power cable.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 추계학술대회 논문집 전력기술부문
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• pp.100-102
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• 2007

본 논문에서는 혼합정수 선형계획 법을 이용하여 장기 전력계통 계획수립시 최적의 설비를 투자할 수 있는 기법을 제안하였다. 발전설비와 송변전설비는 하나의 망으로 연결되어 상호 보완적 영향을 주기 때문에 계통계획시 두 설비를 동시에 평가하는 것이 무엇보다 중요하다. 또한 계획기간 전체에 대해 투자비를 고려하여 비용을 최소화해야 한다. 이를 위해 선형계획법을 계통계획에 도입하여 최소비용의 투자비를 가지고 공급 신뢰도 기준를 만족할 수 있는 최적 장기 전력계통 계획 수립기법을 개발하였다. 개발된 기법을 Garver 6모선 계통 및 제3차 전력수급기본계획에 대해 모의하여 결과의 타당성을 검증하였다.

• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.495-501
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• 2017

The introduction of smart grid, which is an innovative application of digital processing and communications to the power grid, might lead to more and more cyber threats originated from IT systems. In other words, The Energy Management System (EMS) and other communication networks interact with the power system on a real time basis, so it is important to understand the interaction between two layers to protect the power system from potential cyber threats. This paper aims to identify and clarify the cyber security risks and their interaction with the power system in Smart Grid. In this study, the optimal power flow (OPF) and Power Flow Tracing are used to assess the interaction between the EMS and the power system. Through OPF and Power Flow Tracing based analysis, the physical and economic impacts from potential cyber threats are assessed, and thereby the quantitative risks are measured in a monetary unit.

• ETRI Journal
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• 제32권6호
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• pp.940-949
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• 2010

Rack-level DC power supply is the optimal technology for providing DC power to a volume server without any power infrastructure changes in an existing AC data center. In this paper, we propose a smartly controllable and monitorable DC rack power system. The proposed system improves power efficiency by changing the power distribution architecture of a conventional method in the rack. We developed an optimal power control method in multipower modules to provide high efficiency at low loads. In addition, the proposed system provides real-time web monitoring of the rack power and environment around a rack. In our experiments, the proposed system improved the power efficiency by over 10% compared to an AC power system providing N+1 redundant power and power monitoring.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 A
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• pp.70-73
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• 1992

With regard to the supply of electric power in better quality, the problem of lightning is becoming more and more important in the operation of an electric power system. In this article a description is given of the new lightning position and tracking system which will be installed in KEPCO. The system is based on the principle of time-of-arrival (TOA) rather than the conventional direction-finding (DF) method.

• Nuclear Engineering and Technology
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• 제54권10호
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• pp.3595-3603
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• 2022

Nuclear safety-class DCS is used for nuclear reactor protection function, which is one of the key facilities to ensure nuclear power plant safety, the maintenance for DCS to keep system in a high reliability is significant. In this paper, Nuclear safety-class DCS system developed by the Nuclear Power Institute of China is investigated, the model of reliability estimation considering nuclear power plant emergency trip control process is carried out using Markov transfer process. According to the System-Subgroup-Module hierarchical iteration calculation, the evolution curve of failure probability is established, and the preventive maintenance optimization strategy is constructed combining reliability numerical calculation and periodic overhaul interval of nuclear power plant, which could provide a quantitative basis for the maintenance decision of DCS system.

• 조명전기설비학회논문지
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• 제24권6호
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• pp.177-182
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• 2010

전력계통은 첨단기술과 함께 발전하고 있다. 최근 전력계통은 새로운 기술개발, 전기설비 및 운영 방법으로 전력계통 운영이 복잡해지고 있다. 전기설비가 발전함에 따라 전력계통의 사고비율이 감소하였지만, 그에 따라 새로운 운영방법이 필요하다. 계통 운영방법이 복잡해짐에 따라 효율적으로 전력계통 운영자들을 훈련시키고 교육시키는 전력계통 시뮬레이터가 필요하게 되었다. 본 논문에서는 LabVIEW 프로그램의 TCP/IP 통신을 이용하여 실시간 전력계통 교육용 시뮬레이터를 제작하였다. 제작한 시뮬레이터는 실제 전력계통에서 일어나는 예측하지 못한 다양한 사건으로 교육자를 지도할 수 있게 제작하였다.

• 대한전기학회논문지:전력기술부문A
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• 제55권3호
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• pp.128-132
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• 2006

Interstate electric power system, as an alternative for energy cooperation under regional economic bloc, has been hotly debated before progressing the restructure in electric power industry and rapidly expanded in many regions after 1990s. Especially, since northeast asia has strong supplementation in resource, load shape, fuel mix etc., electric power system interconnection in this region may bring considerable economic benefits. Moreover, since Korean electric power system has a great difficulty in a geographical condition to interrupt electricity transaction with other countries, it has been expanded as an independent system to supply all demand domestically. As a result, Korean electric power system makes considerable payment for maintaining system security and reliability and expands costly facilities to supply a temporary summer peak demand. Under this inefficiency, if there are electricity transactions with Russia via the North Korea route then economic electric power system operation nay be achieved using seasonal and hourly differences in electricity price and/or load pattern among these countries. In this paper, we estimate price cap of transacted electricity via interstate electric power system in northeast asia. For this study, we perform quantitative economic analysis on various system interconnection scenarios.

• International Journal of Precision Engineering and Manufacturing-Green Technology
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• 제5권5호
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• pp.623-630
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• 2018

The renewable energy systems have been in the spotlight as an alternative for environmental issues. Therefore, the governmental policies are being implemented to spread of promote power generation system using renewable energy in various countries around the world. In addition, Korea has also developed a policy called the power trading contract which can profit from electricity produced from renewable power generation system through Korea Electric Power Corporation (KEPCO) and Korea Power Exchange (KPX). As a result, the power trading contracts can trade power after self-consuming in-house by using small-scale renewable power system for residential customers as well as electricity retailers. The power trading contracts applicable as a small-scale power system have a 'Net metering (NM)' and a 'Power Purchase Agreement (PPA)', and these two types of power trading contracts trade surplus power, but payment method of each power trading is different. The microgrid proposed in this paper is based on grid connected microgrid using Photovoltaic (PV) system and Energy Storage System (ESS), that supplied power to residential demand, we evaluate the operation cost of microgrid by power demand in each power trading contracts and propose the appropriate power trading contracts according to electricity demand.