• KEPCO Journal on Electric Power and Energy
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• v.6 no.3
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• pp.315-319
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• 2020

The modern transportation and mobility sector is expected to encounter high penetration of Electric Vehicles (EVs) because EVs contribute to reducing the harmful emissions from fossil fuel-powered vehicles. With the prospective growth of EVs, sufficient and convenient facilities for fast charging are crucial toward satisfying the EVs' quick charging demand during their trip. Therefore, the Fast Electric Vehicle Charging Stations (FECS) will be a similar role to gas stations. In this paper, we study a charging scheduling problem for the FECS with solar photovoltaic (PV) and an Energy Storage System (ESS). We formulate an optimization problem that minimizes the operational costs of FECS. There are two cost and one revenue terms that are buying cost from main grid power, ESS degradation cost, and revenue from the charging fee of the EVs. Simulation results show that the proposed scheduling algorithm reduces the daily operational cost by effectively using solar PV and ESS.

• KEPCO Journal on Electric Power and Energy
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• v.7 no.1
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• pp.107-114
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• 2021

High penetration of renewable energy generators causes unnecessary investment for power system facilities. Especially with Korean government policies such as Renewable Energy 3020 and Inter-connection support Responsibility of KEPCO for 1 MW DERs, the applications of DER interconnection in distribution system have been increasing. To save the investment, smart control functions for DERs are required and the test bed for the inverters which have not been prepared are necessary to insure DER inter-connection stability. For this, test bed for advanced functions of a smart inverter has been constructed and the tests for necessary functions have been implemented. In this paper, the test bed and environment as well as specifications are introduced and the test results for the validation of the functions are analyzed.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2007.11a
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• pp.112-119
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• 2007

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1597-1598
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• 2015

Regenerative power utilization is one of the most interesting issue in electric railway systems. Generally, technologies to utilize regenerative power from railway vehicles are railway substation with regenerative inverter, on-station energy storage systems, and on-board energy storage systems. In this paper, the electric power loss for those technologies is calculated and compared using DC electric railway system analysis algorithm.

• Journal of Family Resource Management and Policy Review
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• v.14 no.3
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• pp.53-68
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• 2010

This study tried to develop the theoretical backgrounds, explaining consumers energy consumption behavior and analyzed its effects. In other words, this study investigated the factors influencing the amount of electronic energy consumption. In this study, we used 678 questionnaires which were selected a quota sampling by living area who were above 20 years old and married. Summary of results of this study follows. First, attitude for energy saving was positively related with female, high school graduated large size of family members, elderly, and middle-class consumers. In addition, consumers' search for energy saving were appeared passively in young consumers under 30 years old, and the family with the highest household income. Consumers' purchasing energy-efficient products was presented in large size of family members, and young consumers. Second, consumers' environmental oriented behavior, action-directed behavior, healthseeking behavior were significantly related with energy saving behavior, and active information search for energy saving, but not with purchasing energy-efficient products and consuming behavior of electrical energy. Third, the quantity of electric energy consumption was affected by the size of family members, the living size of house related with high energy demand, the attitude for energy saving, and searching information for energy-saving.

• Journal of the Korean Society of Safety
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• v.25 no.5
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• pp.15-21
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• 2010

Regenerative Energy Storage System(ESS) is a system that saves regenerative energy which generated instantly in the regenerative braking of Electric Multiple Unit(EMU) and disappear, and reuse the stored energy when EMU is in powering. Such system related to a research field of renewable energy which emerged concerning climate change and high oil prices. In the case of existing domestic rolling stock, about 25% to 30% of generated regenerative energy is restored to power source and is regarded as direct factor of raising catenary voltage. Such rapid change of catenary voltage is a cause of the failure of EMU's electronic equipment and lowering its reliability and is also a cause of train's fault occurred by tripping circuit breaker. In this paper, we intend to investigate the effect on blending characteristics of electric-braking and pneumatic-braking whether the regenerative energy storage system is used or not in urban transit DC 1,500V feeding system, while trains run. And we also intend to investigate its effect on stabilization of the blending, fluctuation of catenary voltage and various electric equipments.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.6
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• pp.753-763
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• 2016

High temperature sodium/sulfur battery(Na/S battery) has good electrochemical properties, but, the battery has some problems such as explosion and corrosion at al. because of using the liquid electrodes at high temperature and production of high corrosion. Room temperature sodium/sulfur batteries (NAS batteries) is developed to resolve of the battery problem. To recently, room temperature sodium/sulfur batteries has higher discharge capacity than its of lithium ion battery, however, cycle life of the battery is shorter. Because, the sulfur electrode and electrolyte have some problem such as polysulfide resolution in electrolyte and reaction of anode material and polysulfide. Cycle life of the battery is improved by decrease of polysulfide resolution in electrolyte and block of reaction between anode material and polysulfide. If room temperature sodium/sulfur batteries (NAS batteries) with low cost and high capacity improves cycle life, the batteries will be commercialized batteries for electric storage, electric vehicle, and mobile electric items.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.631-636
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• 2018

This paper proposed an optimal operation strategy for a hybrid energy storage system (HESS) with a lithium-ion battery and lead-acid battery for mild hybrid electric vehicles (mild HEVs). The proposed mild HEV system is targeted to mount the electric motor and the battery to a conventional internal combustion engine vehicle. Because the proposed mild HEV includes the motor and energy storage device of small capacity, the system focuses on low system cost and small size. To overcome these limitations, it is necessary to use a lead acid battery which is used for a vehicle. Thus, it is possible to use more energy using HESS with a lithium battery and a lead storage battery. The HESS, which combines the lithium-ion battery and the secondary battery in parallel, can achieve better performance by using the two types of energy storage systems with different characteristics. However, the system requires an operation strategy because accurate and selective control of the batteries for each situation is necessary. In this paper, an optimal operation strategy is proposed considering characteristics of each energy storage system, state-of-charge (SOC), bidirectional converters, the desired output power, and driving conditions in the mild HEV system. The performance of the proposed system is evaluated through several case studies with respect to energy capacity, SOC, battery characteristic, and system efficiency.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.9
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• pp.85-96
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• 2010

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 $CO_2$ emissions shall be addressed as important issues 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. The efficient use of regenerated energy is considered to save energy. Namely, Using regenerative energy is that to store the energy generated during braking and discharge it again when a vehicle accelerates. Reusing energy stores and discharges energy, consequently enables a complete exchange of energy between vehicles, even if they are not braking and accelerating at precisely the same time, as is most frequently the case in everyday service. This paper analyzes effects of energy saving and $CO_2$-cut by using regenerative energy of electric vehicles.

• Journal of Convergence for Information Technology
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• v.11 no.6
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• pp.40-48
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• 2021

The paper dealt with the fact that the green deal took place when the demand for electrical energy surged. However, the procurement of electric vehicles and much of the electric energy of the future still depends on fossil fuels. Accordingly, the importance of the IT industry is highlighted, and the demand for hydrogen-electric vehicles and related industries increases. The method of this study investigated the relevance of EV charging as a future next-generation power source rather than the electric energy demand of the IT industry. This study derives the correlation between industrial electricity and household energy PPP according to economic growth through empirical regression analysis. As the result, it was found that the amount of change, including electric and next-generation electric vehicles, was significant for on thirds of the countries in the change in purchasing power compared to GDP. This affects overall purchasing power as twelve out of thirty two countries with EV demand (Italy, Canada, Switzerland, Poland, Slovenia, Germany, Slovakia, Finland, Sweden, Czech Republic, Estonia, Denmark) are more sensitive to electric energy. This is related to the charging of EVs or hydrogen as the next-generation power of the future rather than the electric energy demand of the IT industry. By preventing waste of unused electricity of IT-electric energy sources and charging-preserving hydrogen electricity, it seems indispensable to prepare for the national IT power conservation buffer facility for supply and demand in future growth.