• 디지털융복합연구
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• 제17권7호
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• pp.131-138
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• 2019

전 세계 전력 생산 에너지의 비율은 석탄이 40%, 천연가스 20%, 수력 16%, 원자력 15%, 석유 6%로 모두가 환경오염을 유발하는 에너지다. 또한 화석연료는 지구상에 자원의 편중이 심하기 때문에 가격과 공급면에서 심각한 문제를 야기한다. 이러한 문제로 화석 연료를 대체하게 될 차세대 친환경 에너지로써 태양광 에너지가 각광 받고 있다. 이에 본 연구에서는 국내 공단에 Test-Bed를 선정하여 수용가의 대응용 태양광 ESS 시스템 적용함에 있어 Peak-cut 운영을 위한 Charge Operation Plan과 Discharge Operation Plan 운영방안을 최대수요전력 감소 시뮬레이션을 통해 검증하고자 한다. 이를 위해 전력사용량이 가장 많은 11월부터 2월의 전력사용량을 선정하여 Charge/Discharge Logic을 적용했다. 본 논문에서 제시한 충전/방전 로직에 따른 시뮬레이션 결과, ESS Peak-cut 서비스 이후의 최대수요전력이 감소하였으며 Peak-target 전력의 50%로 감소함에 따라 계약전력 또한 감소함을 알 수 있다. 이를 통해 계약전력 감소는 해당 수용가의 기본 전력 값을 감소시켜, 경제적 우월성을 기대할 수 있을 뿐만 아니라 전기품질 향상 및 전력공급시스템의 안정화에도 기여할 수 있을 것으로 판단된다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.513-516
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• 2001

In this study, the properties of MCMB anode Mixed with KCF were evaluated. KCF material was used as not only conducting agent but also active material. The Electric conductivity of MCMB and KCF were 23.7S/cm and 45.8S/cm. Characteristics of anode with different KCF contents were the best effect at 2wt%. The 1st Ah efficiency of cells were increased with increment of KCF contents. The internal resistance and the rate capability were 1.59Ω and 135mAh/g at 2C. The discharge capacity was gradually faded with the charge-discharge cycling to about 50th cycles.

• 한국안전학회지
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• 제25권4호
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• pp.19-24
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• 2010

A large amount of electrostatic charges is often generated on polymer powders in fluidized bed and thereby may lead to electrostatic problems. In this study, to evaluate electrostatic hazards of powder in fluidized bed, the electric field(E[v/m]) and the charge amount(q[c/g]) during fluidizing were monitored. We also investigated the Minimum Ignition Energy(MIE [J]) of sample powder used in fluidized bed with the Hartman vertical-tube apparatus. The batch-type fluidized bed system and 2kg as Polypropylene(PP) resin powders were used in the experiments. The following results were obtained: (1) Even when a safe margin of several times was considered, the values of E obtained with PP powder in this paper did not exceed 3 to 5kV/cm, at which an incendiary electrostatic discharge could occur. (2) the ave. q was -0.26${\mu}$C/g during fluidizing. This value was high enough to cause electrostatic agglomeration and adhesion. (3) the entrained PP powder in upper column due to fluidizing could be ignited by electrostatic discharges of 71mJ.

• Journal of Electrical Engineering and Technology
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• 제6권3호
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• pp.397-401
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• 2011

The response of lightning impulse voltage was explored in dielectric liquids employing hydrodynamic modeling with three charge carriers using the finite element method. To understand the physical behavior of discharge phenomena in dielectric liquids, the response of step voltage has been extensively studied recently using numerical techniques. That of lightning impulse voltage, however, has rarely been investigated in technical literature. Therefore, in this paper, we tested impulse response with a tip-sphere electrode which is explained in IEC standard #60897 in detail. Electric field-dependent molecular ionization is a common term for the breakdown process, so two ionization factors were tested and compared for selecting a suitable coefficient with the lightning impulse voltage. To stabilize our numerical setup, the artificial diffusion technique was adopted, and finer mesh segmentation was generated along with the axial axis. We found that the velocity from the numerical result agrees with that from the experimental result on lightning impulse breakdown testing in the literature.

• 한국산학기술학회논문지
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• 제10권8호
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• pp.1795-1801
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• 2009

본 연구는 태양광과 자가발전을 이용한 휴대가능한 손전등 기술로서 전기를 사용할 수 없는 극한 상황에서 수동으로 자가발전을 할 수 있도록 구성하였다. 주간에는 태양전지를 이용하여 배터리를 충전시키고, 태양광을 이용 할 수 없는 경우에는 손잡이를 회전하여 전기를 발전시켜 배터리를 충전하도록 구성하였다. 빛의 밝기를 개선하기 위해 광학 렌즈를 이용하여 빛을 집광시켜 빛의 밝기를 개선하며, 저소비전력 회로를 구성하여 램프 방전 시, 소비전력을 억제하여 장기간 사용이 가능하도록 하였다. 배터리 충전 및 외부 휴대용 기기를 충전하기 위한 안정적인 정전압/정전류 회로를 구성하여 안정적인 충전이 이루어지도록 하였다. 배터리 장기간 사용하지 않는 경우, 배터리의 과방전이 이루어지지 않도록 과방전 회로를 구성하고, 과충전이 이루어지지 않도록 보호회로를 장착하였다. 또한 가정용 아답터를 이용하여 상시 충전이 가능하도록 하였다. 이와 같은 결과로 자가발전 손전등을 구현하였으며, 평상 시 주간에는 태양광으로 충전이 가능하며, 또한 가정용 사용전원으로 충전이 가능하도록 구현하였다. 그리고 광학 렌즈기술을 적용하여 빛의 밝기가 극대화되어 원거리 조사기능이 가능하며, 야간에도 독서가 가능한 백색 자연광을 발산하도록 구현하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.754-760
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• 2011

In the DC traction system, a large load current of electric railcar leads to a voltage drop when a vehicle starts, and the regenerative power generated by brake system increases the catenary voltage. To minimize the voltage fluctuation during the train operation and make use of the regenerative power, several types of energy storage systems are being studied. The energy storage system that is being recently introduced consists of the supercapacitors for energy storage and the bi-direction DC/DC converter for charge/discharge control. The efficiency of the energy storage system depends on the train operation pattern. In this paper, the operation efficiency of the energy storage system was quantitatively analyzed via simulation study taking consideration of the train operation patterns. The simulation was conducted changing the headway of trains with the energy storage system that uses the bi-direction DC/DC converter and supercapacitor. The simulation results showed that the operation efficiency of the energy storage system increases as the headway increase.

• 전자공학회논문지SC
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• 제44권1호
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• pp.67-73
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• 2007

본 연구에서는 특정 자동차에 대한 Charging 시스템의 적합성 여부를 판별할 수 있는 충방전 Balance 시뮬레이터의 Prototype을 개발 하였다. 차량운전 환경요건에 따른 운전 패턴 등, 시뮬레이터의 구성을 위해 각종 전기부하와 이와 관련된 배터리 모델링을 하였고 실차실험을 행하여 그 데이터를 분석 정리하였다. 제안하는 모델과 분석된 데이터를 바탕으로 충방전 시뮬레이터를 개발하였고, 개발된 시뮬레이터는 정해진 차종으로 임의의 주행환경으로 운전할 때 차량의 전기에너지 공급 문제를 실차실험을 한 것과 같이 분석할 수 있다

• 한국유체기계학회 논문집
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• 제15권1호
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• pp.27-35
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• 2012

A numerical simulation for particle collection efficiency in a wire-plate electrostatic precipitator (ESP) has been performed. Method of characteristics and finite differencing method (MOC-FDM) were employed to obtain electric field and space charge density, and lattice boltzmann method (LBM) was used to predict the Electrohydrodynamic (EHD) flow according to the ion convection. Large eddy simulation (LES) was considered for turbulent flow and particle simulation was performed by discrete element method (DEM) which considered field charging, electric force, drag force and wall-collision. One way coupling from FDM to LBM was used with small and low density particle assumption. When the charged particle collided with the collecting plate, particle-wall collision was calculated for re-entertainment effect and the effect of gravity force was considered.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2002년도 추계학술대회
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• pp.279-284
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• 2002

All-vanadium redox flow battery(VRFB) has been studied actively as one of the most promising electrochemical energy storage systems for a wide range of applications such as electric vehicles, photovoltaic arrays, and excess power generated by electric power plants at night time. CPCS has been shown to have the characteristics as an excellent current collector for VRFB and electrochemical properties of specific resistivity 0.31 $\Omega$cm, which were composed of G-1028 80 wt%, PVC 10 wt%, DBP 5 wt% and FS 5 wt%. Energy efficiencies of VRFB with the CPCE and the existing electrode assembly were 84.14 % and 77.24 % respectively, in charge/discharge experiments at constant current of 200 mA, and the CPCE was confirmed to be suitable as the electrode of VRFB.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.966-971
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• 2009

The recent environmental protection trend requires more strict energy saving, therefore every transportation system should reduce energy consumption to the minimum value. High-efficiency operation system, energy saving and CO2 emissions shall be addressed as important issue in railway system. These issues are the most essential factors of railway, compared to major public transportation system. Recently, saving energy in the electric railway system has been studied. For such new energy saving, the Energy storage system is considered for saving energy. Energy saving is possible by efficient use of regenerated energy. Regenerated energy is recycled amongst vehicles by mean of charge and discharge corresponding to powering and braking of electric vehicle operations. This energy saving contributes to cut CO2 to reduce greenhouse gas emissions. Recycling regenerated energy demonstrate significant effect on peak cut of consumption energy in railway substation. Absorption of excess energy avoids regeneration failure due to high traction voltage. This paper presents effects by applying the energy storage system to SeoulMetro Line 2.