• Journal of the Korean Solar Energy Society
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• v.32 no.3
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• pp.26-32
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• 2012

A current compensation method to reduce the mismatch loss in PV systems is proposed as a way to increase the power generation efficiency. A dc-dc converter is used to supply currents to irregular modules in a PV string and is powered from the string output. The converter's voltage conversion ratio is adjusted so that all the modules in the string are operated at the maximum power point. The power rating and size of the converter can be reduced since only the current difference between the regular and irregular module may be supplied. The compensated string shows very little voltage mismatch compared to other regular strings. The validity of the proposed method is verified through a simulation and experiments in a prototype PV system.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.299-303
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• 2011

This paper proposes a novel sensorless maximum power point tracking (11PPT) algorithm for PV systems. The method is based on dividing the operating time into several intervals in which the PV terminals are short circuited in one interval and the calculated short-current of the PV is obtained and used to determine the optimum operating point where the maximum output power can be obtained. The proposed MPPT algorithm has been introduced into a current-controlled boost converter whose duty ratio is controlled to the maintain MPP condition. The same sequence is then repeated regularly capturing the PV maximum power. The main advantage of this method is eliminating the current sensor. Meanwhile, this MPPT algorithm reduces the power oscillations around the peak power point which occurs with perturbation and observation algorithms. In addition, the total cost will decrease by removing the current sensor from the PV side. Finally, simulation results confirm the accuracy of the proposed method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.2
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• pp.1036-1043
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• 2014

The installation of PV system to the power distribution system is being increased as one of solutions for environmental pollution and energy crisis. Because the output efficiency of PV system is getting decreased because of the aging phenomenon and several operation obstacles, the technology development of output prediction and state diagnosis of PV modules are required in order to improve operation performance of PV modules. The conventional methods for output prediction by considering various parameters and standard test condition values of PV modules may have difficult and complex computation procedure and also their prediction values may produce large error. To overcome these problems, this paper proposes an optimal prediction algorithm and state diagnosis algorithm of PV modules by using least square methods of linear regression analysis. In addition, this paper presents a state diagnosis evaluation system of PV modules based on the proposed optimal algorithms of PV modules. From the simulation results of proposed evaluation system, it is confirmed that the proposed algorithms is a practical tool for state diagnosis of PV modules.

• Journal of the Korean Solar Energy Society
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• v.28 no.3
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• pp.60-66
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• 2008

This study is to investigate an optimal size and position of PV system for apartment complex through the electrical load matching analysis. The 4 types of arrangements of apartment buildings are considered as follows; ㅡtype, alternative ㅡtype, ㄱtype and ㅁtype. We assume that the studied site is composed of 9 buildings. Firstly, solar access evaluation of roof and facade in apartment buildings was performed with the hourly simulations of total received insolation on each surface considering the shading effect of buildings. Electrical load profile of typical Korean apartments were investigated for the load matching analysis. To calculate an annual total PV output, we used MERIT program which is a hourly based load matching tool developed by ESRD. TRY weather data of Daejeon are applied for this analysis. Result shows that approximately 11% of total electric load of the site can be supplied by the PV system in the case of full installation of PV system at the whole south-face roof area of 9 buildings in this stuided apartment complex. Depending on a various installation option of roof and facade area, the possible ratio of PV supply in total electrical load varies from 9% to 42%. Among the 4 arrangement types, the ㅡtype revealed the best option for the maximum output of PV system.

• Journal of Integrative Natural Science
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• v.15 no.3
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• pp.99-110
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• 2022

Solar photovoltaic (PV) system shows a non-linear current (I) -voltage (V) characteristics, which depends on the surrounding environment factors, such as irradiance, temperature, and the wind. Solar PV system, with current (I) - voltage (V) and power (P) - Voltage (V) characteristics, specifies a unique operating point at where the possible maximum power point (MPP) is delivered. At the MPP, the PV array operates at maximum power efficiency. In order to continuously harvest maximum power at any point of time from solar PV modules, a good MPPT algorithms need to be employed. Currently, due to its simplicity and easy implementation, Perturb and Observe (P&O) algorithms are the most commonly used MPPT control method in the PV systems but it has a drawback at suddenly varying environment situations, due to constant step size. In this paper, to overcome the difficulties of the fast changing environment and suddenly changing the power of PV array due to constant step size in the P&O algorithm, least mean Square (LMS) methods is proposed together with P&O MPPT algorithm which is superior to traditional P&O MPPT. PV output power is predicted using LMS method to improve the tracking speed and deduce the possibility of misjudgment of increasing and decreasing the PV output. Simulation results shows that the proposed MPPT technique can track the MPP accurately as well as its dynamic response is very fast in response to the change of environmental parameters in comparison with the conventional P&O MPPT algorithm, and improves system performance.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.259-261
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• 2003

Generally, there is an input capacitor in front of PV(Photovoltaic) inverter in DG(Distributed Generation). This input capacitor mainly works in order to stabilize the PV output voltage. However, input capacitors, which are being used in domestic market are not well known about their appropriate value and also there is no information for selecting the suitable value of input capacitor. Therefore, the author suggests that the stand-alone PV inverter is considered to analyse appropriate value of input capacitor and then recommends the appropriate value of input capacitor through simulation.

• Journal of Power Electronics
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• v.18 no.4
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• pp.997-1006
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• 2018

This paper proposes a transformerless photovoltaic (PV) power converter system based on the DC/AC boost inverter, which can solve the leakage current and second-order ripple power issues in single-phase grid-connected PV inverters. In the proposed topology, the leakage current can be decreased remarkably since most of the common-mode currents flow through the output capacitor, by-passing parasitic capacitors, and grounding resistors. In addition, the inherent ripple power component in the single-phase grid inverter can be suppressed without adding any extra components. Therefore, bulky electrolytic capacitors can be replaced by small film capacitors. The effectiveness of the proposed topology has been verified by simulation and experimental results for a 1-kW PV PCS.

• 한국태양에너지학회:학술대회논문집
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• 2008.11a
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• pp.48-52
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• 2008

The photovoltaic modules are affected by heat. The hotter the PV module, the lower the power output, then the life time will be short. If the cell temperature rises above a certain limit the encapsulating materials can be damaged, and this will degrade the performance of the PV module. This paper presents that the PV module temperature can be estimated by using thermal analysis programs, and demonstrates the thermal characteristics of the PV module.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1290-1292
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• 2001

Photovoltaic(PV) power generation system has been extensively studied and watched with keen interest as a clean and renewable power source. On the other hand, because the output power of solar cell is not only unstable but uncontrollable, the maximum power point tracking(MPPT) control is still hot issue with the tracking failure left unsolved under the sudden fluctuation of irradiance. Hence, in this paper, we introduce the mechanism of the tracking failure under the fluctuation of irradiance, and show the simulation results using SPRW(simulation method for PV power generation system using real weather conditions).

• 한국태양에너지학회:학술대회논문집
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• 2008.04a
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• pp.49-54
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• 2008

This study is to investigate an optimal size and position of PV system for apartment complex enough the electrical load matching analysis. The 4 types of arrangements of apartment buildings are considered as follows; ㅡtype, alternative ㅡtype, ㄱtype and ㅁtype. We assume that the studied site is composed of 9 buildings. Firstly, solar access evaluation of roof and facade in apartment buildings was performing with the hourly simulations of total received insolation on each surface considering the hading effect of buildings. Electrical load profile of typical Korean apartments was investigated for the lad matching analysis. To calculate an annual total PV output, we used MERIT program which is a sourly based load matching tool developed by ESRU. TRY weather data of Daejeon are applied for this analysis. Result shows that approximately 11% of total electric load of the site can be supplied by the PV system in the case of full installation of PV system at the whole south-face roof area of 9 buildings in this stuided apartment complex. Depending of a various installation option of roof and facade area, the possible ratio of PV supply in total electrical load varies from 9% to 42%. Among the 4 arrangement types, the ㅡ type revealed the best option for the maximum output of PV system.