• Title/Summary/Keyword: A photovoltaic system

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A Hierarchical CPV Solar Generation Tracking System based on Modular Bayesian Network (베이지안 네트워크 기반 계층적 CPV 태양광 추적 시스템)

  • Park, Susang;Yang, Kyon-Mo;Cho, Sung-Bae
    • Journal of KIISE:Software and Applications
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    • v.41 no.7
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    • pp.481-491
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    • 2014
  • The power production using renewable energy is more important because of a limited amount of fossil fuel and the problem of global warming. A concentrative photovoltaic system comes into the spotlight with high energy production, since the rate of power production using solar energy is proliferated. These systems, however, need to sophisticated tracking methods to give the high power production. In this paper, we propose a hierarchical tracking system using modular Bayesian networks and a naive Bayes classifier. The Bayesian networks can respond flexibly in uncertain situations and can be designed by domain knowledge even when the data are not enough. Bayesian network modules infer the weather states which are classified into nine classes. Then, naive Bayes classifier selects the most effective method considering inferred weather states and the system makes a decision using the rules. We collected real weather data for the experiments and the average accuracy of the proposed method is 93.9%. In addition, comparing the photovoltaic efficiency with the pinhole camera system results in improved performance of about 16.58%.

The Heating Performance Evaluation of Heating System with Building-Integrated Photovoltaic/Thermal Collectors (실험을 통한 건물통합형 태양광·열(BIPVT) 시스템의 난방성능 평가)

  • Jeong, Seon-Ok;Kim, Jin-Hee;Kim, Ji-Seong;Park, Se-Hyeon;Kim, Jun-Tae
    • Journal of the Korean Solar Energy Society
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    • v.32 no.6
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    • pp.113-119
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    • 2012
  • The heat from PV modules should be removed for better electrical performance, and can be converted into useful thermal energy. A photovoltaic-thermal(PVT) module is a combination of PV module with a solar thermal collector which forms one device that produce thermal energy as well as electricity. In many studies various water type PVT collectors have been proposed in effort to increase their electrical and thermal efficiency. The aim of this study is to evaluate the heating performance of heating system combined with PVT collectors that on integrated building roof. For this study, the BIPVT system of 1.5kWp was installed at the experimental house, and it was incorporated with its heating system. From the experimental results, the solar fraction of the heating system with BIPVT was 15%. It was also found that was analyzed that the heating energy for the house can be reduced by 47%, as the heat gained from BIPVT system pre-heated the water used for heating system.

Composition of efficient monitoring system using an interpolation (보간법을 이용한 효율적인 모니터링 시스템 구성)

  • Lee, Sang-Hyeok;Kang, Feel-Soon
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.12 no.2
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    • pp.290-298
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    • 2008
  • This paper presents an efficient data storage and reconstruction method in data acquisition and processing of monitoring system. The proposed method extracts minimum data using an interpolation from raw data which are acquired from a target system. They are transferred and saved in a monitoring PC via TCP/IP communication, and then reconstructed as original signals. Therefore, it is possible to design an efficient monitoring system by the improved data communication speed due to the reduced communication packet, and it reduces the storage space. The algorithm for data acquisition and reconstruction is based on Cubic Hermite interpolation. To verify the validity of the proposed scheme, we presents simulation results compared with other interpolation based approaches. Finally, it is applied to a monitoring system for grid-connected photovoltaic power generation system to prove the high-performance of the proposed method.

Half and Full-Bridge Cell based Stand-Alone Photovoltaic Multi-Level Inverter (하프ㆍ풀-브리지 셀을 이용한 독립형 태양광 멀티레벨 인버터)

  • Kang Feel-Soon;Oh Seok-Kyu;Park Sung-Jun;Kim Jang-Mok;Kim Cheul-U
    • The Transactions of the Korean Institute of Power Electronics
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    • v.9 no.5
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    • pp.438-447
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    • 2004
  • A new multilevel PWM inverter using a half-bridge and full-bridge cells is proposed for the use of stand-alone photovoltaic inverters. The configuration of the proposed multilevel PWM inverter is based on a prior 11-level shaped PWM inverter. Among three full-bridge cells employed in the prior inverter, one cell is substituted by a half-bridge cell. Owing to this simple alteration, the proposed inverter has three promising merits. First it increases the number of output voltage levels resulted in high quality output voltages. Second, it reduces two power switching devices by means of employing a half-bridge cell. Third, it reduces power imposed on a transformer connected with the half-bridge unit. That is to say, most power is transferred to loads via cascaded transformers connected with low switching inverters, which are used to synthesize the fundamental output voltage levels whereas the output of a transformer linked to a high switching inverter is used to improve the final output voltage waves; thus, it is desirable in the point of the improvement of the system efficiency. By comparing to the prior 11-level PWM inverter, it assesses the performance of the proposed inverter as a stand-alone photovoltaic inverter. The validity of the proposed inverter is verified by computer-aided simulations and experimental results.

Modeling of Practical Photovoltaic Generation System using Controllable Current Source based Inverter (제어 가능한 전류원 기반의 인버터를 이용한 실제적 태양광 발전 시스템 모델링)

  • Oh, Yun-Sik;Cho, Kyu-Jung;Kim, Min-Sung;Kim, Ji-Soo;Kang, Sung-Bum;Kim, Chul-Hwan;Lee, You-Jin;Ko, Yun-Tae
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.8
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    • pp.1340-1346
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    • 2016
  • Utilization of Distributed Generations (DGs) using Renewable Energy Sources (RESs) has been constantly increasing as they provide a lot of environmental, economic merits. In spite of these merits, some problems with respect to voltage profile, protection and its coordination system due to reverse power flow could happen. In order to analyze and solve the problems, accurate modeling of DG systems should be preceded as a fundamental research task. In this paper, we present a PhotoVoltaic (PV) generation system which consists of practical PV cells with series and parallel resistor and an inverter for interconnection with a main distribution system. The inverter is based on controllable current source which is capable of controlling power factors, active and reactive powers within a certain limit related to amount of PV generation. To verify performance of the model, a distribution system based on actual data is modeled by using ElectroMagnetic Transient Program (EMTP) software. Computer simulations according to various conditions are also performed and it is shown from simulation results that the model presented is very effective to study DG-related researches.

The Instantaneous Phase-Tracking in PLL using the DFT Algorithm (DFT 알고리즘을 이용한 PLL의 순시 추종)

  • Kim, Youn-Seo;Yang, Oh
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.45 no.6
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    • pp.141-148
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    • 2008
  • An utility voltage information, including the frequency, phase angle and amplitude is very important in many industrial systems. The grid-connected photovoltaic system in the limelight as alternative energy needs utility voltage information such as frequency, phase angle and magnitude to connect the grid-line. In this paper, it proposes the instantaneous phase-tracking in PLL that uses the frequency from the utility voltage as a sync signal and locks the phase with compensation for phase difference from DPT algorithm. It also proposes not only DFT algorithm execution by every sample not by one period, but also phase-tracking method in a wide range of frequency not a fixed one. This paper shows the feasibility and the usefulness of the proposed methods through the computer simulation and the experiment.

A Utility Interactive Photovoltaic Generation System using PWM Converter (PWM 컨버터를 이용한 계통연계형 태양광발전 시스템)

  • Kim D. G.;Chung J. H.;Chung C. B.;Kim S. N.;Lee S. H.;Kang S. W.;Oh B. H.;Lee H. G.;Kim Y. J.;Han K. H.
    • Proceedings of the KIPE Conference
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    • 2004.07a
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    • pp.133-136
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    • 2004
  • Since the residential load is an AC load and the output of solar cell is a DC power, the photovoltaic system needs the DC/AC converter to utilize solar cell. In case of driving to interact with utility line, in order to operate at unity power factor, converter must provide the sinusoidal wave current and voltage with same phase of utility line. Since output of solar cell is greatly fluctuated by insolation, it is necessary that the operation of solar cell output in the range of the vicinity of maximum power point. In this paper, DC/AC converter is three phase PWM converter with smoothing reactor. And then, feedforward control used to obtain a superior characteristic for current control and digital PLL circuit used to detect the phase of utility line.

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A Utility Interactive Photovoltaic Generation System Using PWM Converter (PWM 컨버터를 이용한 계통연계형 태양광발전 시스템)

  • Chung, J.H.;Jho, J.M.;Jeon, K.Y.;Lee, S.H.;Oh, B.H.;Kim, S.N.;Kim, Y.J.;Han, K.H.
    • Proceedings of the KIEE Conference
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    • 2003.07b
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    • pp.1253-1255
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    • 2003
  • Since the residential load is an AC load and the output of solar cell is a DC Power, the photovoltaic system needs the DC/AC converter to utilize solar cell. In case of driving to interact with utility line, in order to operate at unity power factor, converter must provide the sinusoidal wave current and voltage with same phase of utility line. Since output of solar cell is greatly fluctuated by insolation. it is necessary that the operation of solar cell output in the range of the vicinity of maximum power point. In this paper DC/AC converter is three phase PWM converter with smoothing reactor. And then, feedforward control used to obtain a superior characteristic for current control and digital PLL circuit used to detect the phase of utility line.

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A Single-phase PWM Voltage Source Inverter for Photovoltaic Generation System (태양광 발전시스템을 위한 단상 PWM 전압형 인버터)

  • Yoo, Taek-Bin;Sung, Nark-Kuy;Kang, Seung-Wook;Lee, Seung-Hwan;Lee, Hoon-Goo;Han, Kyung-Hee
    • Proceedings of the KIEE Conference
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    • 1995.07a
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    • pp.443-445
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    • 1995
  • Since the residential load is an AC load, while the output of solar cell is a DC power, the photovoltaic system needs the DC/AC converter to utilize solar cell and must provide the sinusoidal wave current and voltage with unity power factor in the case of driving to Interact with utility line. It is always necessary for the output of solar cell to operate in the vicinity of maximum power point, since it is greatly fluctuated by insolation. This paper treats that we will constitute a single phase PWM voltage source inverter and trace the modulation index which always maximize the output of solar cell in propotion to insolation variation and prove it by simulation that we can provide current wave, which is nearly sinusoidal wave with unity power factor, for load and utility line.

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Photovoltaic Power System using Discontinuous Mode Buck-Boost Chopper (불연속모드 승강압형 초퍼를 이용한 태양광발전시스템)

  • Kim, Young-Cheal;Suh, Ki-Young;Woo, Jung-In;Lee, Hyun-Woo
    • Proceedings of the KIEE Conference
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    • 1998.07f
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    • pp.2115-2117
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    • 1998
  • The output characteristics of solar cell are nonlinear, and these characteristics vary with load solar insolation. solar cell temperature. The PWM power inverter is realized by driving a inverter constructed with a high frequency buck-boost chopper in the discontinuous conduction mode(DCM). This paper present a buck-boost PWM inverter and its application for residential system.

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