• 전력전자학회:학술대회논문집
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• 전력전자학회 2014년도 전력전자학술대회 논문집
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• pp.409-410
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• 2014

본 논문은 독립형 태양광 보안등에 적합한 전력변환기를 제안한다. 제안된 전력변환기는 플라이백-부스트 콤비네이션 전력변환기로 하나의 스위치로 독립형 태양광 보안등의 배터리 감압컨버터와 LED 구동용 승압 컨버터의 기능을 모두 수행한다. 또한 기존 플라이백 컨버터의 RCD 스너버 회로 대신, 출력에 직접 연결하여 누설 인덕터의 에너지를 출력으로 전달하여 손실을 줄이는 방법을 적용하였다. 제안된 회로를 검증하기 위해서 PSIM 시뮬레이터를 사용하였으며, 회로의 동작 및 구조를 설명하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2016년도 추계학술대회 논문집
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• pp.21-22
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• 2016

본 논문에서는 차동전력조절방식을 추가하여 최대 전력점을 추종하는 동시에 출력단에 직렬로 연결된 부하가 전하 균등화 기능을 수행하는 회로를 제안한다. 제안하는 회로는 각각의 PV모듈을 제어를 하고, 이를 상태공간평균화기법을 이용하여 해석하였다. 본 논문에서의 전력조절기는 포워드컨버터로 구성 되어 있고, 주 컨버터인 전하균등화회로는 벅-플라이백컨버터로 구성하였다. 컨버터의 입력은 PV모듈을 직렬로 연결, 출력은 배터리를 직렬로 연결하여 제안한 기능을 구현하였다. 이에 따른 조건을 수식으로 증명하고, MATLAB과 모의 시뮬레이션 프로그램인 PSIM의 Bode plot을 비교하여 이를 검증하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 추계학술대회
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• pp.252-253
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• 2010

본 논문에서는 Molten Carbonate Fuel Cell (MCFC)의 느린 동특성을 Load Leveler와 2차 전지로 구성된 back-up 시스템으로 보완하여 독립운전을 가능하게 한 대용량 연료전지 발전시스템을 제안한다. 제안한 독립운전 시스템의 발전 용량 및 battery 용량은 실제 전력사용 통계자료를 근거로 최적으로 산정되며, 컴퓨터 시뮬레이션을 통하여 타당성을 검증한다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 추계학술대회
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• pp.68-69
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• 2010

자립 운전시 전력조절기는 일반적으로 태양광 발전에서 사용을 할 경우 부하에 의해 출력이 결정되어 최대전력 추종을 할 수 없는 구조로 되어있다. 본 연구에서는 자립 운전시의 태양광 발전시스템이 안정적인 최대전력 추종을 할 수 있도록 에너지 저장장치가 결합된 구조를 제안하였다. 이러한 구조에서는 태양광 발전의 전력 손실을 줄이고 또한 태양광 발전 전력이 부족할 경우에서도 부하 측의 안정적인 동작을 보장하기 위하여 에너지 저장장치와 DC-DC 양방향 컨버터를 이용한다. 에너지 저장장치의 한 예로 슈퍼커패시터를 충 방전함으로써 태양광 발전 에너지에 의한 안정적인 출력을 낼 수 있고, 태양광 발전 전력의 효율적인 사용을 위한 전력조절 시스템의 아키텍처를 제안하고자 한다.

• 한국수소및신에너지학회논문집
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• 제34권2호
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• pp.91-99
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• 2023

Participation in power trading using surplus power is considered a business model active in the domestic energy trade market, but it is limited only if the legal requirements according to the type, capacity, and use of the facilities to be applied for are satisfied. The hydrogen residential demonstration model presented in this paper includes solar power, energy storage system (ESS), fuel cell, and water electrolysis facilities in electrical facilities for private use with low-voltage power receiving system. The concept of operations strategy for this model focuses on securing the energy self-sufficiency ratio of the entire system, securing economic feasibility through the optimal operation module installed in the energy management system (EMS), and securing the stability of the internal power balancing issue during the stand-alone mode. An electric facility configuration method of a hydrogen residential complex demonstrated to achieve this operational goal has a structure in which individual energy sources are electrically connected to the main bus, and ESS is also directly connected to the main bus instead of a renewable connection type to perform charging/discharging operation for energy balancing management in the complex. If surplus power exists after scheduling, participation in power trading through reverse transmission parallel operation can be considered to solve the energy balancing problem and ensure profitability. Consequentially, this paper reviews the legal regulations on participation in electric power trading using surplus power from hydrogen residential models that can produce and consume power, gas, and thermal energy including hybrid distributed power sources, and suggests action plans.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술대회 논문집 전문대학교육위원
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• pp.149-153
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• 2003

This paper presents a current-source-inverter based on a buck-boost configuration and its application for residential photovoltaic system. The proposed circuit has five switches. Among them, only one switch acts as chopping, and the other determine the polarity of output; therefore, it can reduce the switching loss. Because the input inductor current is operated on the discontinuous conduction mode, high power factor can be achieved without additional input current controller. So the overall system shows a simple structure. The operational modes are analysed in depth, and then it was verified through the experimental results using a 150 [W] prototype equipped with digital signal processor TMS320F241.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.812-819
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• 2015

This paper presents a new approach for simulating the internal faults of synchronous machines using distributed computing and Large Change Sensitivity (LCS) analysis. LCS analysis caters for a parallel solution of 3-phase model of a faulted machine within the symmetrical component-based model of interconnected network. The proposed method considers dynamic behavior of the faulty machine and connected system and tries to accurately solve the synchronous machine’s internal fault conditions in the system. The proposed method is implemented in stand-alone FORTRAN-based phasor software and the results have been compared with available recordings from real networks and precisely simulated faults by use of the ATP/EMTP as a time domain software package. An encouraging correlation between the simulation results using proposed method, ATP simulation and measurements was observed and reported. The simplified approach also enables engineers to quickly investigate their particular cases with a reasonable precision.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.169-173
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• 2008

Stirling engine is a promising heat engine with a high efficiency, muti-fuel capability, low emission, quiet operation, very low maintenance and long life. As one of the promising applications, solar power system based on the Stirling dish, providing net solar-to-electric conversion efficiencies reaching 30%, can operate as stand-alone units in remote locations or can be linked together in groups to provide utility-scale power. This paper introduced a new Scroll-type Stirling engine, being developed for solar power, superior to conventional Stirling engines. The Scroll-type Stirling engine is characterized as traits of continuous and wholly separated compression and expansion; one-way flow system; direct cooling and heating the fluid in the working spaces through the extensive inner surfaces of scroll wraps. All theses traits contribute to achieving thermodynamic cycle closer to the ideal Stirling cycle (exactly speaking, Ericsson cycle).

• Journal of Power Electronics
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• 제9권5호
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• pp.679-690
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• 2009

The paper presents a new photovoltaic inverter for stand-alone induction motor application. The proposed system is composed of two stages. First stage is for the photovoltaic dc power feeding and second stage is dedicated to the motor-inverter subsystem and control technique. A direct torque control (DTC) with a novel switching strategy for motor torque ripple minimization is introduced. The novel DTC strategy is based on selecting a suitable voltage vector group for motor torque ripple minimization. A three-level voltage source inverter (VSI) is used instead of a two level inverter because the first has more available vectors and lower ripples in the output current and flux than the second, thus it has lower torque ripples. The photovoltaic array and battery bank are sized and the configuration is indicated based on sun-hour methodology. Simulation results show a comparison between three systems; two level VSI with conventional DTC strategy, three level VSI with conventional DTC, and the proposed system that has a novel DTC switching strategy applied to three level VSI. The results show that the proposed system has lower ripples in the current, flux and torque of the motor.

• 전력전자학회논문지
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• 제21권3호
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• pp.200-206
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• 2016

In the microgrid, inverters for energy storage system are generally constructed in a parallel structure because of capacity expandability, convenience of system maintenance, and reliability improvement. Parallel inverters are required to provide stable voltage to the critical load in PCC and to accurately share the current between each inverter. Furthermore, when islanding occurs, the inverters should change its operating mode from grid-connected mode to stand-alone mode. However, during clearing time and control mode change, the conventional control method has a negative impact on the critical load, that is, severe fluctuating voltage. In this study, a parallel operation control method is proposed. This method provides seamless mode transfer for the entire transition period, including clearing time and control mode change, and has accurate current sharing between each inverter. The proposed control method is validated through simulation and experiment.