• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.231-232
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• 2007

In this paper, a fault diagnosis and control integrated system (FDCIS) was developed to control the thermoelectric (TE) power in the SP-100 space reactor. The objectives of the proposed model predictive control were to minimize both the difference between the predicted TE power and the desired power, and the variation of control drum angle that adjusts the control reactivity. Also, the objectives were subject to maximum and minimum control drum angle and maximum drum angle variation speed. A genetic algorithm was used to optimize the model predictive controller. The model predictive controller was integrated with a fault detection and diagnostics algorithm so that the controller can work properly even under input and output measurement faults. With the presence of faults, the control law was reconfigured using online estimates of the measurements. Simulation results of the proposed controller showed that the TE generator power level controlled by the proposed controller could track the target power level effectively even under measurement faults, satisfying all control constraints.

• 전력전자학회논문지
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• 제15권6호
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• pp.487-497
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• 2010

본 논문에서는 직렬형 하이브리드 자동차의 운전특성을 분석하기 위한 PSIM 시뮬레이터의 개발에 대하여 기술한다. 직렬형 하이브리드 자동차는 엔진이 전동기와 전기적으로 결합되어 있으며 전동기의 출력에 의해서만 구동된다. 엔진/발전기, 전동기, 기어와 같은 파워트레인 각 구성요소들의 정격은 에너지 개념을 이용한 시스템과 Electrical Peaking Hybrid (ELPH)를 이용하여 모델링할 수 있는데, 설계된 하이브리드 자동차를 개발된 PSIM 시뮬레이터를 이용하여 특정 운전주기 하에서 평가하고 분석하였다. 기계적 제동이 사용되는 경우와 회생제동이 사용되는 경우 각각에 대하여 전동기의 평균 입력을 비교하였으며 시뮬레이션 결과를 바탕으로 직렬형 하이브리드 자동차의 연비를 분석하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2018년도 전력전자학술대회
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• pp.180-182
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• 2018

직류배전 시스템은 신재생에너지 및 ESS(Energy Storage System)와의 결합으로 높은 에너지 이용효율을 가질 수 있다. 이러한 직류배전 시스템은 기존 교류계통을 통해 구성되며, 다양한 디지털 부하가 연계되므로 교류계통 및 메인 PCS(Power Conversion System)에 문제가 발생했을 때를 대비하여 비상 전력 공급 시스템이 필수적으로 고려되어야 한다. 최근 직류배전에서 비상 전력 공급 시스템으로 큰 관심을 받고 있는 ESS는 초기 설치비용, 용량, 수명 등의 문제로 인해 단일로 비상 전력 공급 시스템을 구성하기에 어려움이 있다. 때문에 기존에 이미 많이 설치되어 있는 비상발전기의 적용이 검토되어야 한다. 본 논문에서는 비상발전기와 ESS를 활용하여 양극성 저압직류배전에서 정전과 같은 사고 상황 발생 시 직류배전망의 전압을 빠르게 안정시킬 수 있는 시스템과 그 운영기법을 제안하였고, PSIM 시뮬레이션을 통하여 타당성을 검증하였다.

• Nuclear Engineering and Technology
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• 제49권1호
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• pp.92-102
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• 2017

The analysis of steam generators as an interface between primary and secondary circuits in light water nuclear power plants is crucial in terms of safety and design issues. VVER-1000 nuclear power plants use horizontal steam generators which demand a detailed thermal hydraulics investigation in order to predict their behavior during normal and transient operational conditions. Two phase flow field simulation on adjacent tube bundles is important in obtaining logical numerical results. However, the complexity of the tube bundles, due to geometry and arrangement, makes it complicated. Employment of porous media is suggested to simplify numerical modeling. This study presents the use of porous media to simulate the tube bundles within a general-purpose computational fluid dynamics code. Solved governing equations are generalized phase continuity, momentum, and energy equations. Boundary conditions, as one of the main challenges in this numerical analysis, are optimized. The model has been verified and tuned by simple two-dimensional geometry. It is shown that the obtained vapor volume fraction near the cold and hot collectors predict the experimental results more accurately than in previous studies.

• 한국지능시스템학회논문지
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• 제21권6호
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• pp.767-774
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• 2011

최근 풍력발전 시스템은 가장 빨리 발전하고 있는 신재생 에너지원중 하나로 각광을 받고 있으며, 세계 선진 국가들뿐만 아니라 국내에서도 개발과 보급에 많은 투자를 하고 있다. 풍력발전 시스템은 블레이드, 발전기 및 인버터 등으로 구성된 복잡한 시스템으로 최근 들어 풍력발전 시스템의 각 구성요소의 고장에 대한 연구가 활발히 진행되고 있다. 풍력발전과 관련된 고장진단은 주로 진동센서로부터의 신호처리에 의해 기계적인 고장을 검출 및 진단하는 것이 주를 이루고 있다. 이에 본 연구에서는 풍력발전시스템에 사용되고 있는 인버터의 고장진단에 적용될 수 있는 기법을 제안하고자 한다. 또한 시뮬레이션 및 실제 시스템에의 적용을 통해 제안된 제안된 기법의 유용성을 확인하고자 한다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 1997년도 추계학술발표회논문집
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• pp.88-92
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• 1997

Power conversion system must be increased swiching frequency in order to achieve a small size, a light weight and a low noise, However, the swiches of converter are subjected to high switching power losses and switching stresses. As a result of those, the power system brings on a low efficiency. In this paper, the authors propose a DC-DC boost converter of high power by partial resonant switch method (PRSM). The switching devices in a proposed circuit are operated with soft swiching and the control technique of those is simplified for switch to drive in constant duty cycle. The partial resonant circuit makes use of a inductor suing step up and a condenser of loss-less snubber. Also the circuit has a merit which is taken to increase of efficiency, as if makes to a regeneration at input source of accumulated energy in snubber condenser without loss of snubber in conventional cirvuit. The result is the the switching loss is very low and the efficiency of system is high. The proposed converter is deemed the most suitable for high power applications where the power switching devices are used.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.153-156
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• 2001

Maximum Power Point Tracking(MPPT) Is used in wind power generation systems to maximize wind power turbin output power, irrespective of wind speed conditions and of the load electrical characteristics. In this paper we do the equivalent modeling the mechanical energy of wind power turbine according to wind speed into the synchronous generator. We analyse the equivalent modeling output part of rectifier into DC/DC converter input part theoretically. We design a control algorithm for variable voltage according to wind speed intensity and density so that load voltage of chopper is controlled steadily using the maximum power point tracking(MPPT) control method. We analyse a battery charging characteristics and a charging circuit for power storage enabling the supply of stable power to the load. We design a system and do the modeling of it analytically so that it supplies a stable power to the load by constructing a DC-AC inverter point. Also we design a charging circuit usable in actual wind power generation system of 30kW and confirm its validity.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 춘계학술대회 논문집 에너지변화시스템부문
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• pp.38-40
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• 2009

In order to achieve a gearless construction of the wind energy conversion system(WECS), a low-speed generator should be used. Of the various candidate machine types, radial-field, multi-pole, permanent magnet, synchronous machines may be used for low-speed applications. So, this paper deals with the design of direct-coupled, multi-pole radial field machines with permanent magnet(PM) excitation for wind power applications for cogging torque reduction through the determination of optimum pole arc/pitch ratio. On the basis of an equivalent magnetic circuit method(EMCM) and a space harmonic method(SHM), an initial design is performed considering restricted conditions. And then, a detailed design is made using a non-linear finite element analyses(FEA). Finally, test results concerning generating characteristics are given to confirm the validation of the design.

• 한국시스템다이내믹스연구
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• 제6권1호
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• pp.99-123
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• 2005

Although the generation market is competitive, the power market is easily exercised the market power by one generator due to its special futures such as a limited supplier, large investment cost, transmission constraints and loss. Specially, as Korea Electric industry restructuring is similar US competitive wholesale electricity market structure which discovered the several evidences of market power abuse, when restructuring is completed the possibility that market power will be exercised is big. Market power interferes with market competitions and efficiency of system. The goal of this study is to investigate the market price effects of the potential market power and the proposed market power mitigation strategy in Korean market using the forecasting wholesale electricity market model. This modeling is developed based on the system dynamics approach. it can analyze the dynamic behaviors of wholesale prices in Korean market. And then it is expanded to include the effect of market condition changed by 'strategic behavior' and 'real time pricing.' This model can generate the overall insights regarding the dynamic impact of output withholding by old gas fire power plant bon as a marginal plant in Korean market at the macro level. Also it will give the energy planner the opportunity to create different scenarios for the future for deregulated wholesales market in Korea.

• Journal of Electrical Engineering and Technology
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• 제9권5호
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• pp.1643-1653
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• 2014

This paper presents the design and implementation of a wind-solar hybrid power system for LED street lighting and an isolated power system. The proposed system consists of photovoltaic modules, a wind generator, a storage system (battery), LED lighting, and the controller, which can manage the power and system operation. This controller has the functions of maximum power point tracking (MPPT) for the wind and solar power, effective charging/discharging for the storage system, LED dimming control for saving energy, and remote data logging for monitoring the performance and maintenance. The proposed system was analyzed in regard to the operation status of the hybrid input power and the battery voltage using a PSIM simulation. In addition, the characteristics of the proposed system's output were analyzed through experimental verification. A prototype was also developed which uses 300[W] of wind power, 200[W] of solar power, 60[W] LED lighting, and a 24[V]/80[Ah] battery. The control system principles and design scheme of the hardware and software are presented.