• Journal of Power Electronics
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• 제3권4호
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• pp.230-238
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• 2003

Electric vehicles (EV) demands for greater acceleration, performance and vehicle range in pure electric vehicles plus mandated requirements to further reduce emissions in hybrid electric vehicles (HEV) increase the appeal for combined on-board energy storage systems and generators. And the power electronics plays an important role in providing an interface between fuel cells (FC) and loads. This paper deals with a multiple input DC-DC power converter devoted to combine the power flowing of multi-source on energy systems. The multi-source is composed of (i) FC system as a prime power demands, (ii) super capacitor banks as energy storage devices for high and intense power demands, (iii) superconducting magnetic energy storage system (SMES), (iv) multiple input DC-DC power converter and (v) a three phase inverter-fed permanent magnet synchronous motor as a drive. In this system, It is used super capacitor banks and superconducting magnetic energy replaces from the battery system. The modeling and transient performance simulation is effective for reducing transient influence caused by sudden charge of effective load. The main purpose of power electronic converters is to convert the DC power output from the fuel cell and other to a suitable AC voltage, which can be connected to electric loads directly (PMSM). The fuel cell and other output is connected to the DC-DC converter, which regulates the DC link voltage.

• 전력전자학회논문지
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• 제17권6호
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• pp.523-531
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• 2012

This paper proposes a high efficiency power conversion system for battery-ultracapacitor hybrid energy storages. The proposed system has only one bidirectional dc-dc converter for hybrid power source with batteries and ultracapacitors. The hybrid power source has bidirectional switching circuits for selecting one energy storage device. Bidirectional power flow between the energy storage device and high voltage capacitor can be controlled by one bidirectional converter. An asymmetrical switching method is applied to the bidirectional converter for high power efficiency. Switching power losses are reduced by zero-voltage switching of power switches. System operation and design considerations are presented. The experimental results are provided to verify the performance of the proposed system.

• Journal of Information Processing Systems
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• 제13권6호
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• pp.1487-1495
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• 2017

With increasing interests in renewables, more consumers are installing an energy storage system (ESS) in their backyards, and thus, the ESS will play a critical role in the emerging smart grid. Due to mechanical properties, however its operational dynamics must be well understood before connecting the ESS to the smart grid (and eventually to an IT system). To this end, we investigate charging and discharging processes in detail. This paper, then, proposes methods for four type tests (state of charge test, conversion efficiency test, response time test, and ramp rate test) that can assess the dynamics of the ESS. The proposed methods can capture accurate delay values of mechanical processes in the ESS, and it is expected for those values to help design real-time communication systems in the smart grid involving the ESS.

• 스마트미디어저널
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• 제9권1호
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• pp.84-91
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• 2020

신재생 에너지를 활용이 높아지면서 에너지저장시스템의 활용과 효율성에 대한 관심이 높아지고 있다. 특히 태양광 에너지저장시스템을 구성하는 서브시스템에서 이상 징후 발생에 능동적으로 대처할 수 있는 운영이 요구된다. 본 논문은 태양광 발전량 데이터를 표본으로 하여 예측 발전량을 추정하여 에너지 관리하는 방안을 제안한다. 실시간으로 예측된 배터리 충전 전력과 배터리 랙 총 충전 전력을 비교하여 충전 전력을 조절하는 모형을 적용한다. 그 결과로 배터리의 발열 억제 및 충방전율을 유지시켜 에너지저장시스템의 에너지 저장을 안정적으로 높일 수 있다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.697-700
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• 2005

Aquifer Thermal Energy Storage (ATES) system can be very cost-effective and renewable energy sources, depending on site-specific parameters and load characteristics. In order to develop an ATES system which has certain hydrogeological characteristics, understanding of the thermo hydraulic processes of an aquifer is necessary for a proper design of an aquifer heat storage system under given conditions. The thermo hydraulic transfer for heat storage is simulated using FEFLOW according to two sets of pumping and waste water reinjection scenarios of heat pump operation in a two layered confined aquifer. In the first set of model, the movement of the thermal front and groundwater level are simulated by changing the locations of injection and pumping well in seasonal cycle. However, in the second set of model the simulation is performed in the state of fixing the locations of pumping and injection well. After 365 days simulation period, the temperature distribution is dominated by injected water temperature and the distance from injection well. The small temperature change is appears on the surface compared to other slices of depth because the first layer has very low porosity and the transfer of thermal energy are sensitive at the porosity of each layer. The groundwater levels and temperature changes in injection and pumping wells are monitored to validate the effectiveness of the used heat pump operation method and the thermal interference between wells is analyzed.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제12B권1호
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• pp.24-30
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• 2002

The developments of the solar and the wind power energy are necessary since the future alternative, energies that have no pollution and no limitation are restricted. Currently power generation system of MW scale has been developed, but it still has a flew faults with the weather condition. In order to solve these existing problem combined generation system of photovoltaic(400W) and wind power generation system(400W) was suggested. It combines wind power and solar energy to have the supporting effect from each other. However, since even combined generation system cannot always generate stable output with ever-changing weather condition, power storage apparatus that uses elastic energy of spiral spring to combined generation system was also added far the present study. In an experiment, when output of combined generation system gets lower than 12V(charging voltage), power was continuously supplied to load through the inverter by charging energy obtained from generating rotary energy of spiral spring operates in small scale generator.

• 한국통신학회논문지
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• 제42권5호
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• pp.1093-1101
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• 2017

스마트 그리드를 구성하는 기본 단위 요소인 마이크로그리드(Microgrid)는 전력의 중앙 공급방식에서 벗어나 독립된 하나의 체계를 이룬다. 본 논문은 전력변환장치(Power Conditioning System)를 기반으로 마이크로그리드를 계통으로부터 전기적으로 독립시키고, 신재생 에너지원과 에너지 저장장치(Energy Storage System) 등의 분산자원(Distributed Energy Resource)을 활용하여 효과적으로 독립 상태를 유지하고 운영할 수 있는 방법을 제안한다. 계통의 위상검출과 동기화를 통해 계통에 연계하거나 독립 시에 부하에 미치는 영향을 최소화할 뿐만 아니라 계통의 정전 상황에서도 안정적으로 운영이 가능하다.

• 한국수소및신에너지학회논문집
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• 제26권4호
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• pp.331-338
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• 2015

Solar air heaters (SAHs) are simple in design and widely used for solar energy collection devices, and a packed bed is one of typical solar energy storage systems of thermal energy captured by SAHs. This paper presents mathematical modeling and simulation on the thermal performance of various packed bed energy storage systems. A MATLAB program is used to estimate the thermal efficiency of packed bed SAH. Among the various packed bed energy storage systems considered, the wire mesh screen packed bed SAH shows the best thermal efficiency over the entire range of design conditions. The maximum of thermal efficiency of packed bed SAH with wire mesh screen matrices has been found to be 0.794 for Re=2000 - 20000 and ${\Delta}T/I=0.002-0.02$.

• Nuclear Engineering and Technology
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• 제21권3호
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• pp.223-230
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• 1989

본 연구는 이산 모형으로 표현되는 사용후 핵연료 중간 저장 공정을 전산기 모사하였다. 이는 계통 흐름을 보여주며, 기기 성능을 평가하고 계통 구성 요소와 흐름을 확립하여 설계에 관한 계통 구성 및 운전지침에 대한 정보를 제공한다. 공정 모사를 통하여 가장 좋은 시스템을 구성하기 위하여 주요 변수에 대하여 시험 분석하였다. 전산기 모사 결과에 의하면 하루 2교대 및 2대의 냉각 시설이 최적안으로 나타났다. 이산 공정 모사는 저장 시설의 최적 설계와 운전 자료를 얻는데 효과적으로 사용될 수 있다.

• 전기학회논문지
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• 제63권11호
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• pp.1615-1621
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• 2014

A wireless tram which runs without catenary and instead uses batteries installed in the tram has been recently researched actively. This paper presents a new method maximizing absorption of regenerative energy of a wireless tram and extending life cycle of the energy storage device in the wireless tram by applying line-optimized charging and discharging scenario. Energy efficiency and life cycle of energy storage system (ESS) are highly dependent on the characteristic of operating conditions. For example, frequent charge and discharge with high power cause the problems that decrease the battery life cycles. Hybrid energy storage system (HESS) is combination of two ESSs which have complementary characteristics to each other. HESS can provide even better functionality and performance than the battery only ESS due to the synergy effect of two ESSs. This paper also provides a power distribution strategy and driving scenarios which increase the life cycle and energy efficiency of the HESS consisting of a battery and an ultra-capacitor. The developed strategy was tested and verified by a hardware-in-the-loop-simulation (HILS) system which emulates the a wireless tram.