• 대한전기학회논문지:전력기술부문A
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• 제54권9호
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• pp.449-456
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• 2005

The preventive diagnostic technique prevents transformers from power failure through giving alarm and observing transformers in service. And it helps to establish the plan for optimum maintenance of the transformer as well as to find location or cause of fault using accumulated data. Data detection and experience of the preventive diagnostic system need to establish the preventive diagnostic algorithm regarding interrelationship between detected data and deterioration of equipment. Therefore in-depth analysis about the preventive diagnosis system is required. KEPCO has adopted the preventive diagnostic system at nine 345kV substations since 1997. Techniques for component sensors of the preventive diagnosis system were settled but diagnosis algorithm, diagnostic criteria and practical use of accumulated data are not yet established. This paper, to build up the base of preventive diagnostic algorithm for the Power transformer. investigated the preventive diagnostic criteria for the power transformer.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.202-204
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• 2008

RCM(reliability Centered Maintenance) 적용 시 나타나는 장점으로 인해 이미 여러 산업 분야에 적용되고 있다. 설비의 안정성을 중요시하는 원자력발전 부문에서 처음으로 도입 후 전력산업분야 대부분에서 RCM을 적용하거나 적용연구가 진행되고 있다. 철도산업에서도 전력산업 분야와 같이 안정적 이면서 경제적인 전력을 공급하는 것이 중요하므로 정비업무의 중요성이 크다고 할 수 있다. 특히 철도 시스템 중 한전에서 154kV나 345kV를 수전 받아 철도 시스템에 전력을 공급하는 변전소의 역할은 매우 중요하다. 따라서 철도 변전소를 구성하고 있는 설비의 특성과 운영방식에 대한 연구를 통해 적절한 RCM적용 방안을 위한 고장모드 및 임계분석 (FMECA: Failure Mode, Effects and Criticality Analysis) 연구의 필요성이 대두된다. RCM과 FMECA는 적용 산업분야에 따라 적용 절차를 다르게 적용되어진다. 따라서 철도 변전소에 대한 고장데이터와 설비들의 특성 및 현재 운용방식 등을 종합적으로 고려하여 적절한 수립방법 연구가 필요하다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전력기술부문
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• pp.377-379
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• 2001

Contamination flashover is responsible for insulator electrical failures. Particularly, in Korea, with its perennially dry spring, the first spring rain often cause serious line outages by forming a conductive liquid film on the insulator surface. Rainwater and fog are not normally conductive but unfortunately atmospheric dust deposited on the insulator surface contains soluble salts which may lead to bad condition of insulation by combining watery and salts. Transmission design engineers have used a contamination map drawn on the traditional paper map. But it is not convenient because it does not include the information of Geographic Information accurately. This paper explains the newly developed salt contamination map program using Geographic Information System, which provide accurate geographic information. The program is designed to use four parts of datum, salt contamination levels, 345kV & 154 kV transmission lines, power plants & substations and background map. The digital background map is composed of raster files, the others are done by vector map.

• 전기전자학회논문지
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• 제15권4호
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• pp.345-353
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• 2011

최근 휴대 가능한 스마트폰, 노트북과 같은 모바일 기기의 수요가 급격하게 늘어나고 있다. 또한 이러한 기기는 한 제품에 여러 기능을 추가하는 복합화와 대용량의 멀티미디어 기능과 같은 스마트 기능이 주류를 이루면서 더 많은 전력을 소모하게 된다. 이에 따라 기존의 속도와 성능을 향상시키기 위한 노력에서 한정된 배터리 용량을 효율적으로 사용하여 효율을 극대화 시키려는 노력으로 변화하고 있다. 본 논문에서는 임베디드 프로세서를 이용해 이벤트 드리븐 프로그래밍 방식을 사용한 배터리 관리 시스템을 제안하고 제안된 시스템이 SBS(Smart Battery Specification) v1.1을 만족 할 수 있음을 보였다. 제안하는 배터리 관리 시스템의 특징은 기존의 임베디드 시스템에서 실시간 운영체제를 이용한 배터리 관리 시스템에 비해 전체 코드 크기와, 필요한 메모리 크기를 줄 일 수 있다. 또한 Firmware 형태로 구성하여 쉽게 기존의 운영체제에 포함 할 수 있다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.683-686
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• 2000

The chargers for DC power supply of the contro1lers, which have been installed in the relay rooms in 345/154kV substations of KEPCO, lag in both aspects of technique and performance. Moreover, as they are SCR-based, they dont meet the performance requirements of todays digital and automated controllers. Now two controllers are running in pair and one of those is for reservation. There are lots of troubles because the patrol engineering team has to replace them manually whenever they are out of order. So it is expected to bring convenience if the charger replacement is automated. Also, the existing chargers take much space, weight and cost - which have increased the need of development to make them smaller, less expensive, and have high quality. We will develop a charger system which has one fifth of the weight of the existing system by double-integrating the volume. The new system will be ready for a future full unmanned system with integrated pores for remote control, state-of-the-art digital features, and more than 90% efficiency/power factor against 80% efficiency/power factor of the existing system.

• Journal of Electrical Engineering and Technology
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• 제7권3호
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• pp.297-303
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• 2012

This paper presents the simulation results for the analysis of a lightning surge, switching transients and very fast transients within a thermal plant. The modeling of gas insulated substations (GIS) makes use of electrical equivalent circuits that are composed of lumped elements and distributed parameter lines. The system model also includes some generators, transformers, and low voltage circuits such as 24V DC rectifiers and control circuits. This paper shows the simulation results, via EMTP (Electro-Magnetic Transients Program), for three overvoltage types, such as transient overvoltages, switching transients, very fast transients and a lightning surge.

• 한국안전학회지
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• 제21권2호
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• pp.22-28
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• 2006

This paper presents assessment of possibility on the human risk for the electromagnetic field of unbalanced two coupled three-phase transmission line using fuzzy theory. Three phase load flow program was developed which employed a Newton-Raphson method as a tool to analyze system unbalanced. This research presents a method of handling two coupled three phase transmission system unbalance analysis and unbalanced power demand as a function of voltages. As the results of case study, in case of 345[kV] T/L, the electric field intensity was 10.9540[kV/m], magnetic field intensity was 0.2567[G] in severest case. The results showed that the membership of a proposition fuzzy '10.9540 [kV/m] is hazardous' is 0.6349. As the analytic results using the fuzzy qualifier term, the membership in case of very false is 0.1379 and fairly false is 0.6124, respectively. In assessment of fuzzy measure possibility for the electromagnetic field, this paper used probability of fuzzy arid measure of fuzziness technique.

• 전기학회논문지
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• 제62권10호
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• pp.1354-1360
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• 2013

In transmission system, reclosing scheme is very useful method to improve continuity of power supply and reliability of system. Especially, high speed reclosing which is used generally in transmission systems has a benefit improving transient stability. However, the reclosing can jeopardize the stability under the condition having high difference of voltage phase angle between both ends. Thus, this paper proposes optimal sequential reclosing scheme to improve transient stability due to reclosing operation. The optimal sequential reclosing is that each phase is closed sequentially considering transient energy. In this paper, 345kV and 154kV transmission system is modeled using EMTP (ElectroMagnetic Transient Program) to verify the performance and effectiveness of optimal sequential reclosing on transient stability. Also, Integral Square Error(ISE) method is used to assess the transient stability.

• 대한전기학회논문지:전력기술부문A
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• 제52권7호
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• pp.414-420
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• 2003

The domestic needs for larger capability of power sources are increasing to cope with the expanding power load which results from the industrial developments & the progressed life style. In summer, the peak load is mainly due to the non-industrial reasons such as air-conditioners and other cooling equipments. To cover the concentrated peak load in stable, the power transmission lines should be more constructed and efficiently operated. The ampacity design of the underground cable system is generally following international standards such as IEC287, IEC60853 and JCS168 which regards the shape of 100% daily full power loads. It is not so efficient to neglect the real shapes of load curves generally below 60~70% of full load. The dynamic (real time) rating system tends to be used with the measured thermal parameters which make it possible to calculate the maximum ampacity within required periods. In this paper, the CTM(Conductor Temperature Monitoring) which is the base of dynamic rating systems for tunnel environment is proposed by a design of lumped thermal network ($\pi$-type thermal model) and distribution temperature sensor attached configuration, including the estimation results of its performances by load cycle test on 345kV single phase XLPE cable.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.371_372
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• 2009

This paper describes surge characteristics on 345kV combined transmission system mixed overhead line and GIL(Gas Insulated Transmission Line). Then, it is compared with the results of the system mixed overhead line and XLPE power cables. Finally the lightning overvoltages are also discussed according to surge arrester installation in two kinds of combined transmission systems when the lighting strikes on the phase conductor.