• Transactions on Electrical and Electronic Materials
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• 제18권6호
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• pp.350-358
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• 2017

Recently, owing to increased interest in low-carbon energy supplies, renewable energy sources such as photovoltaics and wind turbines in distribution networks have received considerable attention for generating clean and unlimited energy. The presence of energy storage systems (ESSs) in the promising field of active distribution networks (ADNs) would have direct impact on power system problems such as encountered in probabilistic distributed generation (DG) model studies. Hence, the optimal procedure is offered herein, in which the simultaneous placement of an ESS, photovoltaic-based DG, and wind turbine-based DG in an ADN is taken into account. The main goal of this paper is to maximize the net present value of the loss reduction benefit by considering the price of electricity for each load state. The proposed framework consists of a scenario tree method for covering the existing uncertainties in the distribution network's load demand as well as DG. The collected results verify the considerable effect of concurrent installation of probabilistic DG models and an ESS in defining the optimum site of DG and the ESS and they demonstrate that the optimum operation of an ESS in the ADN is consequently related to the highest value of the loss reduction benefit in long-term planning as well. The results obtained are encouraging.

• 전기학회논문지
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• 제65권5호
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• pp.760-768
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• 2016

Recently, as one of the policies for carbon free operation method of independent power system replacing diesel generator with renewable energy such as wind power and photovoltaic(PV) system has been presented. Therefore, this paper proposes an operation algorithm and modeling of independent power system by considering CVCF(constant voltage constant frequency) ESS(energy storage system) for constant frequency and voltage, LC(load control) ESS for demand and supply balancing and SVC(static var compensator) for reactive power compensation. From the simulation results based on the various operation scenario, it is confirmed that proposed operation algorithm and modeling may contribute stable operation and carbon free in independent power system.

• 전기학회논문지
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• 제67권9호
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• pp.1174-1180
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• 2018

In December 2017, the government announced plans to increase the current proportion of renewable energy from 7% to 20% by 2030 through a plan called the Renewable Energy 3020 Implementation Plan. Therefore, the demand for installation of photovoltaic(PV), wind turbine(WT) and battery energy storage system(BESS) is expected to increase. In particular, the system combined with energy storage system(ESS) is expected to take up a large portion since PV and WT can receive high renewable energy certificates(REC) weights when combined with ESS. In this study, we calculate the optimal capacity of the power conditioning system(PCS) and the BESS by comparing the economical efficiency and maximize the efficiency of the PV-BESS system in which the PV and the BESS are connected. By analyzing the system marginal price(SMP) and REC, it maximize profits through application of REC weight 5.0 and optimal charge-discharge scheduling according to the SMP changes.

• 한국가축번식학회지
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• 제14권1호
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• pp.84-91
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• 1990

본 실험은 돼지난포란의 체외성숙과 체외수정 효과를 높일 수 있는 방법을 찾기 위하여 시도되었으며 직경 1~2mm와 3~7mm 난포로부터 채란된 난자를 mKRB(-BSA)에 돼지발정혈청(ESS), FCS 또는 투석돼지난포액(DFF)을 첨가한 성숙배양에서 24~48시간, 37$^{\circ}C$에서 배양하였다. 성숙된 난포란은 정소상체 정자와 24시간 배양 후 전핵행성 여부를 조사하였다. 36~48시간 배양에서 50~60%의 난자가 metaphase II에 도달되었고 난포 크기(1~2mm와 3~7mm)간에 체외성숙율의 차이는 없었으나 3~7mm 난포란에서 성숙분열이 다소 빨랐다. 체외성숙배양액에 5% ESS, 15% FCS 및 DFF 첨가시 대조구보다 다소 성숙율이 높았다. 체외수정율(전핵형성)은 5% ESS와 15% FCS 첨가 성숙시킨 난포란과 체내 수정능획득 정자와의 수정에서 각각 높은 경향이 있었다. 따라서 돼지난포란의 체외성숙과 수정에 ESS, FCS 및 투석난포액이 유효한 요인이 됨을 알 수 있다.

• 전력전자학회논문지
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• 제19권2호
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• pp.194-200
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• 2014

In DC micro-grid system energy storage systems (ESS) are responsible for storing energy and balancing power. Also, control target of the bidirectional DC-DC converter(BDC) for ESS should be changed depending on the operating mode. During the grid connected mode, the BDC controls the battery current or voltage. When a grid fault occurs, the BDC should change the control target to regulate the DC-bus. The BDC with conventional control method may experience large transient state during the mode change. This paper proposes a control method of BDC for ESS. The proposed control method is able to provide autonomous and seamless mode transfer by a variable current limiter. To validate the proposed concept, simulation results using PSIM and experimental results from a 2kW prototype are provided.

• 전력전자학회논문지
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• 제19권2호
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• pp.106-115
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• 2014

This paper proposes ESS DC-DC Converter using Redox Flow Battery (RFB) for stand-alone microgrid. Price, safety, expandability and dynamics are crucial in ESS. Reports show that Zinc-bromine (ZnBr) RFB is the best choice in ESS. Simple electrical ZnBr RFB model is obtained from charging test. DC-DC converter Inductor current-DClink Voltage model is proposed for the DC microgrid. For the controller design in z-domain, the K-factor method is by considering nature of the digital controller. The control performance has been verified with simulation and hardware experiments. Lastly 10kW DC microgrid using RFB test result is shown.

• 한국태양에너지학회 논문집
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• 제32권1호
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• pp.25-31
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• 2012

This paper presents the characteristics of power generation output at Haeng-won wind farm and how to determine the optimized ESS capacity for power stabilizing. Depend on the fluctuation rate of wind power output variation, wind farm capacity and site, power stabilization will be impacted. Therefore, we need to determine proper ESS capacity. Using the actual data of Haeng-won wind farm from 2009. 3 to 2010.2., capacity of ESS was determined by moving average value. To verify the proposed algorithm, simulations are carried out with PSCAD/EMTDC program. As a result, optimal ESS capacity of Haeng-won wind farm in Jeju is estimated about 1.63 MWh.

• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.51-59
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• 2018

Despite the advantages of energy arbitrage using energy storage systems (ESSs), the high cost of ESSs has not attracted storage owners for the arbitrage. However, as the costs of ESS have decreased and the price volatility of the electricity market has increased, many studies have been conducted on energy arbitrage using ESSs. In this study, the existing two-period model is modified in consideration of the ESS cost and risk-free contracts. Optimal investment strategies that maximize the sum of external effects caused by price changes and arbitrage profits are formulated by market participants. The optimal amounts of ESS investment for three types of investors in three different market structures are determined with game theory, and strategies in the form of the mixed-complementarity problem are solved by using the PATH solver of GAMS. Results show that when all market participants can participate in investment simultaneously, only customers invest in ESSs, which means that customers can obtain market power by operating their ESSs. Attracting other types of ESS investors, such as merchant storage owners and producers, to mitigate market power can be achieved by increasing risk-free contracts.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 전력전자학술대회
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• pp.339-340
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• 2017

본 논문은 에너지 저장시스템(ESS)과 무정전 전원장치(UPS)를 하나로 통합한 새로운 하이브리드 ESS-UPS 시스템을 제안한다. 제안하는 시스템은 ESS와 UPS를 하나로 통합함으로써 전력변환 시스템(PCS)의 가격을 줄이고 배터리의 이용률을 높일 수 있다. 또한 기존의 on-line UPS와는 달리 두 종류의 중요부하를 구성할 수 있어 PCS의 용량대비 비상발전 용량을 증대시키는 것이 가능하다. 본 논문에서는 제안하는 하이브리드 ESS-UPS 시스템의 운영 전략 및 급속 모드전환 알고리즘을 제안하며, 5kW급 축소 시작품을 통한 실험 결과로 타당성을 입증하였다.

• Current Photovoltaic Research
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• 제11권4호
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• pp.124-133
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• 2023

In order to deploy the large-scale energy storage (ES) service in the various industry, it is very important to develop a business model with high technological and economic feasibility through detailed valuation of cost and expected benefits. In relation to this, this paper established an optimal scheduling plan for electric vehicle charging stations connected with photovoltaic (PV) and ES technologies in Korea using the distributed energy resource valuation tool and analyzed the feasibility of the project. In addition, the impact of incentives such as REC (Renewable Energy Certificate) to be given to electric vehicle charging stations in accordance with the relevant laws to be revised in the future was analyzed. As a results, the methodology presented in this paper are expected to be used in various ways to analyze the feasibility of various business models linked to renewable energy and ES technologies as well as the electric vehicle market.