• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.9-20
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• 2018

When a large-scale photovoltaic (PV) system is introduced into a distribution system, the customer's voltage may exceed the allowable limit ($220V{\pm}6%$) due to voltage variations and reverse power flow in the PV system. In order to solve this problem, we propose a method for adjusting the customer voltage using the existing step voltage regulator (SVR) installed in the primary feeder. However, due to the characteristics of a mechanically operating SVR, the customer voltage during the tap changing time of the SVR is likely to deviate from the allowable limit. In this paper, an energy storage system (ESS) with optimal operation strategies, and an appropriate capacity calculation algorithm are proposed, and the parallel driving scheme between the SVR and the ESS is also proposed to solve the customer voltage problem that may occur during the tap changing time of the SVR. The simulation results show that the allowable limit of the customer voltage is verified by the proposed methods during the tap changing time of the SVR when the large-scale PV system is connected to the distribution system.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1056-1057
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• 2015

A common DC bus is a useful connection for several DC output sources such as photovoltaic (PV), fuel cells, and batteries. Operation of the common DC power system with more than two DC output sources, especially in a stand-alone mode, requires a control scheme for the stable operation of the system. In this paper, a control scheme has been developed for applying DC power sources to the distribution system. The purpose of the control scheme is to make the best use of the DC power sources. The DC power system consists of PV, two energy storage systems and a DC-AC inverter with the control scheme. A distribution system was modeled in PSCAD/EMTDC. As the results, the control scheme is applied to the DC-AC inverter and the DC-DC converter for transfer operations between the grid-connected and the stand-alone mode to keep the DC bus and the AC voltage constant. The results from the simulation demonstrate the stable operation of a grid connected DC power system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.36-42
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• 2019

Europe and North America are paying attention to residential ESS(Energy Storage System) that can manage energy efficiently. The ESS is a system that stores and manages the electric power by charging and discharging the battery. The ESS is generally used in conjunction with photovoltaic systems. The ESS supplies the load of the power generation time and stores the remaining PV power to supply the load at the non-power generation time. However, due to the high price of residential ESS, low electric rates and increasing block rates, there is no market of residential ESS in Korea. This paper reviews the price condition and the capacity for applying PV and residential ESS to household of apartments using HOMER in Korea.

• Journal of the Korean Solar Energy Society
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• v.32 no.spc3
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• pp.245-254
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• 2012

In photovoltaic system, the characteristics of photovoltaic module such as open circuit voltage and short circuit current will be changed because of cell temperature and solar radiation. Therefore, the boost converter of a PV system connects between the output of photovoltaic system and DC link capacitor of grid connected inverter as controlling duty ratio for maximum power point tracking(MPPT). This paper shows the dynamic characteristics of the boost converter by comparing single-loop and two-loop control algorithm using both analog and digital control. Both proposed compensation methods have been verified with computer simulation to demonstrate the validity of the proposed control schemes.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.10-13
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• 2000

This paper proposes the virtual implementation of solar cell(VISC) for photovoltaic system. It is required to make operation condition of solar cell arrays where is the limit of time and space, The main advantage of the simulator is its ability to simulate different types and sizes of arrays considering V-I characteristics of data sheet. The VISC with buch-boost converter can be used to study the short-term and long-term performances of PV cells. The simulator is a far more cost effective and reliable replacement for field and filight testing.

• Journal of Magnetics
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• v.19 no.3
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• pp.295-299
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• 2014

Recently, module-integrated converter (MIC) research has shown interest in small-scale photovoltaic (PV) generation. The converter is capable of efficient power generation. In this system, the high frequency transformer should be made compact, and demonstrate high efficiency characteristics. This paper presents a core structure optimization procedure to improve the efficiency of a high frequency transformer of compact size. The converter circuit is considered in the finite element analysis (FEA) model, in order to obtain an accurate FEA result. The results are verified by the testing of prototypes.

• Proceedings of the KIPE Conference
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• 2019.11a
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• pp.214-215
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• 2019

최근 신재생에너지 시스템의 보급 및 확산에 따라 자가발전시스템에 관한 연구가 활발히 이루어지고 있다. 특히 도시의 빌딩에 에너지를 효율적으로 공급 및 관리하기 위해 다양한 발전원의 하이브리드 시스템의 필요성이 대두되고 있다. 본 논문에서는 태양광(PV, Photovoltaic), 연료전지(FC, Fule Cell), 바나듐 레독스 흐름전지(VRFB, Vanadium Pedox Flow Battery)를 사용하여 도시형에 적합한 빌딩용 신재생에너지 하이브리드 발전/저장 시스템을 제안한다.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.6
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• pp.507-514
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• 2013

In this paper, the proposed charging algorithm is converted from the charging mode to compensate the transient state in the solar battery charging system. The maximum power point tracking (MPPT) control methods and the various charging algorithms for the optimal battery charging are reviewed. The proposed algorithm has excellent transient characteristics compare to the previous algorithm by adding the optimal control method to compensate the transient state when the charging mode switches from the constant current mode to the constant voltage mode based on the conventional constant-current constant-voltage (CC-CV) charging algorithm. The effectiveness of the proposed method has been verified by simulations and experimental results.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.615-617
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• 2008

본 논문에서는 태양에너지 실증연구단지에 설치된 서로 다른 2기 3kW급 태양광발전 시스템에 대한 5년간의 데이터 분석을 통하여 시스템 구성요소인 태양전지와 인버터의 효율 특성 및 시스템의 운전특성의 경년변화에 대하여 비교분석하였다. A 시스템의 경우 PV 어레이 변환효율은 2004년 이후 약 0.2% 정도로 지속적으로 떨어지는 추세를 나타내고 있으며, B 시스템의 경우 인버터의 효율은 약 0.5% 정도로 지속적으로 떨어지는 추세를 나타내고 있다. 2기의 PV 시스템의 발전효율, 이용율 및 성능비는 모두 2004년 이후 지속적인 효율저하를 나타내고 있음을 확인 하였다.

• Proceedings of the KIEE Conference
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• 2008.10c
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• pp.158-160
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• 2008

본 논문에서는 일사량과 온도 및 실부하 패턴이 고려된 3kW급 계통 연계형 태양광 발전시스템의 플랫폼을 제시하였다. 가정의 실제 전력 사용패턴 분석을 위해 하루의 일사량과 온도가 고려된 PV 시뮬레이터와 24시간 실부하의 사용패턴을 이용하여 부하모델링을 수행하였다. 또한 제안된 PV 시뮬레이터와 부하모델링을 적용하여 계절별, 시간별 태양광 발전 전력과 실부하의 전력사용량을 비교 분석 하였으며 시뮬레이션을 통해 타당성을 검증하였다.