• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.11
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• pp.84-93
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• 2009

In this paper, we propose to study the possibility of using a photovoltaic system combined with a high speed micro-turbine. This hybrid system can work as stand-alone system or grid connected system as it will be a part of a micro-grid. Initially, we propose Matlab/Simulink dynamic models of photovoltaic, micro turbine systems and supercapacitor. Then, we carry out a simulation comparison of the two systems, this is, with supercapacitor and without supercapacitor bank. We show that supercapacitor bank as short-term storage device was necessary to reduce the fast fluctuation of power in the case of sensitive loads. It is verified the simulation results of Matlab/Simulink based hybrid power system represent the effectiveness of the suggested hybrid power system.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.6
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• pp.433-441
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• 2020

This study proposes a constant power tracking algorithm to compensate for the intermittent characteristics of Photovoltaic connected to a DC micro grid. A PV-ESS integrated module in which distributed ESS is additionally connected is utilized for the proposed algorithm. PV performs P&O MPPT control at all times. To supplement the intermittent characteristics of PV, the proposed constant power tracking algorithm maintains constant power by operating the distributed ESS of the PV-ESS integrated module in accordance with the output state of the PV. By performing PSIM simulation and an experiment, this study verifies the performance of the integrated module of PV-ESS for DC micro grids applying the constant power tracking algorithm.

• Journal of the Korea Convergence Society
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• v.6 no.1
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• pp.29-34
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• 2015

As smart grid techniques developed, public attention is concentrating on energy efficiency. So it is necessary to study on new renewable energy in order to manage the energy within micro grid consisting smart grid. Among them, small hydro energy has the advantage of being installable anywhere depending the amount of water used by the users within micro grid. This study examines if the measured value is appropriate for small hydro power generation by measuring generation quantity and operation rate of generator based on the sewage flow used by apartments and multi-unit dwellings where those users live. Some appropriate apartments and multi-unit dwellings generate electricity with small hydro generator using sewage as potential energy. This study intends to suggest more effective management by introducing energy management system and electricity storage device of micro grid.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.109.1-109.1
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• 2011

KEPCO was operating power plants with diesel generators in 49 islands including Baekryeong-Do, and the generation capacity was about 66 MW in 2008. The cost of fuel is increasing by the international oil price inflation and continuous rise of oil price is predicted. For the stabilizing of electric power supply to the separate islands, renewable energy and fuel cell systems were considered. Hydrogen is made using renewable energy such as wind power and solar energy, and then a fuel cell system generates electricity with the stored hydrogen. Though the system efficiency is low, it is treated as the only way to secure the stable electric supply using renewable energy at this present. The analytic hierarchy process was used to select suitable candidate island for the system installation and 5 islands including Ulleung-Do were selected. Economic evaluation for the system composed of a kerosene generator, a wind power, an electrolysis, and a fuel cell system was conducted with levelized generation cost based on present value methode. As the result, the necessity of renewable energy combined generation system and micro grid composition in the candidated islands was confirmed. Henceforth, the development of an integration technology which connects micro grid to the total power grid will be needed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.6
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• pp.892-897
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• 2017

Until now, it has been for choosing most economic result to be generally used for designing remote MicroGrid (MG) system. It is able to make economic benefit by reducing operation cost, but proportion of renewable energy will be minimum. In other words, it is difficult to get an effect by renewable energy because economic feasibility is an only consideration. Therefore, various factors should be considered and design objectives should be are diversified to design proper remote MG system. In this paper, remote MG system is classified into two types according to design objectives, and they are analysed through case study based on economic evaluation. In addition, economic feasibility for each type is analysed through sensitivity analysis according to various factors that affect the design results of the system.

• Journal of Convergence for Information Technology
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• v.9 no.1
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• pp.68-73
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• 2019

This study is the central axis of the MG (Micro-Grid) configuration and it has the link through the modular hybrid power source and the DC bus, and it provides the function to detect and block the illegal connection by using the standard socket, And to achieve stabilization. Development of power conversion device, smart distribution panel, integrated control system and efficient demand management are required, and compatibility with MG whole system is urgent. This is a hybrid power generation system that is safe with a common power connection protocol and can be easily connected to anyone. This makes it easy to manage data and prepare for expansion of various manufacturers' systems.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.11
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• pp.1800-1805
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• 2016

The micro-grid designed as bipolar ${\pm}750V$ low-voltage DC power distribution system demonstrated by KEPRI, demands interconnection of a number of small decentralized power source including variable renewable generator. Therefore, variable researches for the influence of interconnection with the bipolar typed DC grid and these variable power sources are required for superior quality of power distribution. Renewable power generation simulators for the bipolar ${\pm}750V$ low-voltage DC power distribution system are necessary for such researches. In this paper, we carry out a research on the photovoltaic simulator that be actually able to interconnect with a bipolar ${\pm}750V$ low-voltage micro-grid. Simulator for this research is not only able to simulate photovoltaic generation according to weather informations and PV modules characteristics, but also contribute to stabilization of bipolar ${\pm}750V$ low-voltage of the system. Therefore, the simulator was designed to develop a system that can situationally respond to variable control algorithms such as the MPPT control, droop control, EMS power control, etc.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.313-316
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• 2006

As Decentralized Generation(DG) becomes more reliable and economically feasible, it is expected that a higher application of DG units would be interconnected to the existing grids. This new market penetration of DG technologies is linked to a large number of factors like technologies costs and performances, interconnection issues, safety, market regulations, environmental issues or grid connection constrains. Korea Electric Power Corporation (KEPCO) has researched performance characteristics of the 60k W class 1) basic start-up & shutdown operation analysis 2) interconnection test 3) MGT -absorption chiller-heater system in the local condition. Variations of heat recovery from exhaust gas has measured according to micro gas turbine output of 15, 30, 45, 60kW. From those results, the performance of the MGT-absorption chiller/heater system has been evaluated. The suggested strategy and experience for the evaluation of the distributed generation will be used for the introduction of other distributed generation technologies into the grid in the future.

• New & Renewable Energy
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• v.2 no.3
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• pp.15-22
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• 2006

As the distributed generation becomes more reliable and economically feasible, it is expected that a higher application of the distributed generation units would be interconnected to the existing grids. This new market penetration using the distributed generation technology is linked to a large number of factors like economics and performance, safety and reliability, market regulations, environmental issues, or grid connection standards. KEPCO, a government company in Korea, has performed the project to identify and evaluate the performance of Micro Gas Turbine(MGT) technologies focused on 30, 60kW-class grid-connected optimization and combined Heat & Power performance. This paper describes the results for the mechanical, electrical, and environmental tests of MGT on actual grid-connection under Korean regulations. As one of the achievements, the simulation model of Exhaust-gas Absorption Chiller was developed, so that it will be able to analyze or propose new distributed generation system using MGT. In addition, KEPCO carried out the field testing of the MGT Cogeneration system at the R&D Center Building, KEPCO. The field test was conducted in order to respond to a wide variety of needs for heat recovery and utilization. The suggested method and experience for the evaluation of the distributed generation will be used for the introduction of other distributed generation technologies into the grid in the future.

• Journal of Power Electronics
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• v.15 no.5
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• pp.1318-1328
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• 2015

The photovoltaic (PV) power conditioning system for small-scale applications has gained significant interest in the past few decades. However, the standalone mode of operation has been rarely approached. This paper presents a two-stage multi-level micro-inverter topology that considers the different operation modes. A multi-output flyback converter provides both the DC-Link voltage balancing for the multi-level inverter side and maximum power point tracking control in grid connection mode in the PV stage. A modified H-bridge multi-level inverter topology is included for the AC output stage. The multi-level inverter lowers the total harmonic distortion and overall ratings of the power semiconductor switches. The proposed micro-inverter topology can help to decrease the size and cost of the PV system. Transient analysis and controller design of this micro-inverter have been proposed for stand-alone and grid-connected modes. Finally, the system performance was verified using a 120 W hardware prototype.