• Journal of Power Electronics
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• 제19권6호
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• pp.1566-1574
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• 2019

Maximum power point tracking (MPPT) under the partial shading condition is a challenging research topic for photovoltaic systems. Shaded photo-voltaic module result in complex peak patterns on the power versus voltage curve which can misguide classical MPPT algorithms. Thus, various kinds of global MPPT algorithms have been studied. These have typically consisted of partial shading detection, global peak search and MPPT. The conventional partial shading detection algorithm aims to detect all of the occurrences of partial shading. This results in excessive execution of global peak searches and discontinuous operation of the MPPT. This in turn, reduces the achievable power for the PV module. Based on a theoretical investigation of power verse voltage curve patterns under various partial shading conditions, it is realized that not all the occurrences of partial shadings require a global peak search. Thus, an intelligent partial shading detection algorithm that provides exact identification of global peak search necessity is essential for the efficient utilization of solar energy resources. This paper presents a new partial shading determinant algorithm utilizing adaptive threshold levels. Conventional methods tend to be too sensitive to sharp shading patterns but insensitive to smooth patterns. However, the proposed algorithm always shows superb performance, regardless of the partial shading patterns.

• 한국농림기상학회지
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• 제23권3호
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• pp.163-168
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• 2021

광은 식물 광합성에 반드시 요구되는 에너지이다. 차광의 종류를 전면차광과 부분차광으로 구분하고, 각각의 차광 조건에서 생육한 콩의 엽록소 형광을 관측하여 광합성능을 평가하였다. 전면차광에서는 SPAD값으로 대표되는 엽록소 농도와 광이용효율을 표현하는 ETR (Electron Transport Rate)이 크게 낮아졌다. 차광 박스 제거 후에 SPAD와 ETR 모두 대조구와 같은 정도가 되었으나, 열 소산 기작을 나타내는 NPQ (Non-Photochemical fluorescence Quenching)는 높아졌다. 이렇게 전면차광을 겪었던 콩의 광이용효율은 회복했지만, 높아진 NPQ가 광인산화 효율을 떨어뜨리므로 실제 노지 광합성량은 필연적으로 낮아질 것이다. 부분 차광에서도 SPAD와 ETR이 대조구와 큰 차이를 보이지 않았으나, NPQ는 높은 모습을 보였다. 따라서, 도시 농업 또는 영농형 태양광과 같은 부분차광 조건의 광합 성량은 단순히 작물의 광이용효율과 누적 광 에너지량으로 계산한 추정값보다 작을 것으로 예상된다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 전력전자학술대회
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• pp.136-137
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• 2017

Maximum power point tracking (MPPT) under partial shading condition (PSC) is a challenging process in the PV array system. The shaded PV panel makes different peak patterns on the P-V curve and misguides the MPPT algorithm. Various kinds of global MPP (GMPP) detecting algorithms are used to overcome this issue. Generally, too frequent execution of GMPP tracking algorithm reduces the achievable power of PV panel due to time spent on the scanning process. Thus, partial shading detection algorithm is essential for efficient utilization of solar energy source. While conventional method only detects fast shading patterns, the proposed algorithm always shows superb performance regardless of the speed of partial shading patterns.

• Journal of Power Electronics
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• 제17권6호
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• pp.1600-1610
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• 2017

We propose maximum power extraction from a rooftop solar photovoltaic (PV) array during partial shading conditions. Partial shading is unavoidable during power extraction from rooftop PV systems due to nearby tall buildings (construction of additional floors) and trees (growth of trees). Many reconfiguration techniques can be used to extract maximum power in partial shading conditions, but in several cases, the real maximum power output is not achieved. In this study, a new switched PV technique is proposed to enhance the power output. The proposed technique is simple to use and more cost effective than other reconfiguration techniques. Therefore, it is suitable for rooftop applications. The power output of the proposed technique is compared with that of existing techniques with similar shading patterns. Eight panels with ratings of 250 watts (2 kW) each are used for testing. MATLAB simulation and hardware verification are done for the proposed and existing techniques. The proposed technique is implemented on a $4{\times}2$ PV array, although it can be extended to a number of arrays.

• 한국태양에너지학회 논문집
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• 제36권4호
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• pp.41-47
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• 2016

A bypass diode is connected in parallel to solar cells with opposite polarity. The advantage of using the bypass diode is circumvented a destructive efforts of hot-spot heating in the photovoltaic(PV) module. In addition, it is possible to reduce a energy loss under the partial shading on the PV module. This paper presents a characteristic of photovoltaic module under partial shading condition and with defective bypass diode by using the experimental data. The results of field testing for each photovoltaic modules, when photovoltaic system which is connected power grid is operating, the inner junction-box temperature of shading photovoltaic module is high $5^{\circ}C$ because of difference of flowing current through into bypass diode. And incase of not operating photovoltaic system, the inner junction-box temperature of module with defective bypass diode is greatly higher than partial shading PV module.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 추계학술대회
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• pp.40-41
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• 2011

Partial shading on a Photo Voltaic panel can generate the local maximum power points on the powervoltage curve of the panel. Presence of the local peaks can disturb the efficient operation of maximum power point tracking (MPPT).In this study, the MPPT under partial shading condition is investigated. To circumvent the trappings into the local peaks, the results of the study are enumerated and discussed.

• Journal of international Conference on Electrical Machines and Systems
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• 제2권1호
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• pp.65-68
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• 2013

A photovoltaic array exhibits several local and single global maximum power points under partial shading conditions. To track the global maximum power point precisely, a novel global maximum power point tracking scheme is proposed in this paper. In the proposed scheme, robustness of the tracking performance has been improved by enhancing searching profile. In addition, the paper addresses the tracking failure condition, and provides the experimental verification with several simulation and experimental results.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2022년도 추계학술대회
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• pp.120-120
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• 2022

Agrivoltaic System (AVS) was introduced with the concept that it could generate electricity by using the extra light remain after crops use for photosynthesis in farm, which can earn additional income. However, crop yield was declined under the AVS condition due to the decrease in light energy. In the past, many researchers have been studied about crop states under shading conditions. However, the phenomenon of partial shading such as under the AVS is not well studied. In this study, to figure out the response of crop under the different light conditions, the electron transport rate (ETR) and non-photochemical quenching (NPQ) of rice was investigated using the chlorophyll fluorescence measurement. Also, physiological changes of crops under the shading conditions were investigated. The growth experiment under partial shading under AVS and overall shading which made of 35% shade cloth was conducted to understand the eco-physiological responses of rice to light in terms of the photosynthesis. Under the shading conditions, SPAD value and chlorophyll contents were higher, but the leaf thickness was lower than control. The overall shading condition show lower ETR than others during the growing season. In contrast, NPQ was higher than other treatments. This means the available light energy cannot contribute to photosynthesis under the shading condition.

• 반도체디스플레이기술학회지
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• 제21권1호
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• pp.114-118
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• 2022

The photovoltaic system is affected by various conditions such as temperature and irradiance. Because non-uniform irradiation and partial shading conditions affect the entire string of cells connected in series, a bypass diode is used to bypass the current flow normally. In order to find the maximum power point in partial shade conditions, it is necessary to estimate various methods of maximum power point tracking. In this paper, the hybrid method of MPPT using Lambert W function and perturbation & observation algorithm is proposed under partial shading conditions. The simulation results are obtained using MATLAB/Simulink and shows the improvement of the accuracy of MPPT.

• 대한건축학회논문집:구조계
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• 제35권5호
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• pp.169-179
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• 2019

During the initial design stage of apartment complex, the photovoltaic(PV) system has been considered as an alternative of renewable energy system and planned to install at the rooftop floor level in general. The electric power generation characteristics can be influenced by the block layout, building orientation and roof top structure because of azimuth angle, tilt angle, and partial shading. This study aims to investigate power generation characteristics of photovoltaic system in apartment buildings by considering the partial shading conditions due to the block layout, building orientation and roof-top structures. For the photovoltaic module arrangement planning in rooftop floor level, shading areas were firstly analyzed due to the adjacent building structure. And the annual and seasonal power generation of PV system were analyzed through the PVsyst simulation results. The results show that shading period at the roof top surface can be increased due to the parapet and water tank. Initial design power capacity can be decreased by considering the daily insolation period and distance between PV modules through the shading simulation. As the number of PV modules decreases, the annual power generation can be decreased. However annual power generation per unit area of PV modules can be increased and performance ratio can be increased above 80%. Also the power generation of PV system can be critically affected by building orientation and the performance ratio can be drastically decreased in east-oriented buildings due to the shading problems caused by adjacent structures at roof top level such as parapet and water tank.