臺灣博碩士論文加值系統

　　本研究主旨在利用有限元素分析法(FEA)探討在受到重力和風力作用下，聚光型太陽能發電系統結構形變之情形。針對中央大學所發展製作之原型聚光型太陽能發電系統，模擬其在不同情況下之結構形變，分別為無風之情況，以及在風速6 m/s和17.2 m/s之情況，同時也計算聚光型太陽能發電系統之結構形變，對每個聚光透鏡對準太陽光線角度所產生之角度偏差量。
　　藉由量測聚光型太陽能發電系統某些位置在實際操作情況下之應變變化，並與模擬結果作比對，可驗證本研究所建立的有限元素分析模型之有效性。比對結果顯示，模擬結果之應變改變趨勢和實驗結果一致，此一致性證實本研究所建立之有限元素分析模型之有效性，適用於分析聚光型太陽能發電系統之結構形變。根據von Mises準則，在所模擬分析之聚光型太陽能發電系統的各個組件中，預期將不會有結構破損之情形發生。
　　模擬分析結果顯示，對於給定之聚光型太陽能發電系統在任何仰角中，聚光透鏡最大之位移量將發生於各個集光器角落之聚光透鏡上，並隨著風速的增加而增加。受重力單獨作用及遭受風速6 m/s和17.2 m/s之情況下，所造成聚光透鏡對準太陽光線角度之偏差值分別為0.19o、0.19o和0.48o，這些數值皆小於對於一個高效率的聚光型太陽能發電系統所要求之可接受角度偏差值0.5o，因此，本研究中所分析之聚光型太陽能發電系統在風速17.2 m/s之情況下，仍可以正常運作，預期不會有明顯的發電效率下降。

　　The purpose of this study is to investigate the effects of gravity and wind loads on the structural deformation in a high concentrated photovoltaic (HCPV) system by means of finite element analysis (FEA). A prototypical HCPV system design being developed at the National Central University was applied in the current study to simulate the structural deformation under three different conditions, namely, no wind and wind speeds of 6 m/s and 17.2 m/s. Furthermore, the misalignment of solar radiation for Fresnel lenses caused by the structural deformation of the HCPV system was also calculated.
　　In order to verify the validity of the constructed FEA model, the simulation results were made a comparison with the measurements of strain change at certain locations in the given HCPV system during field operation. The trend of the strain variation with the elevation angle in the simulation agreed with that in the measurement. Such an agreement validates the constructed FEA model in simulation of the structural deformation for the given HCPV system. Based on the von Mises criterion, no failure was predicted for all the structural components in the given HCPV system.
　　The results show that the maximum resultant displacement of the Fresnel lens occurred at the corners of the arrays of photovoltaic concentrators for the given HCPV system at all elevation angles. The maximum misalignment values of solar radiation were 0.19o, 0.19o, and 0.48o for the conditions of gravity effect alone and wind speeds of 6 m/s and 17.2 m/s, respectively. These values were all below the acceptable values 0.5o for a highly efficient HCPV system. Therefore, the given HCPV system can normally operate under a wind speed of 17.2 m/s without significant degradation of efficiency in power generation.

LIST OF TABLES...............................................................................................................VI
LIST OF FIGURES............................................................................................................VII
1. INTRODUCTION......................................................................................................... 1
1.1 Solar Energy.......................................................................................................... 1
1.2 High Concentrated Photovoltaic System............................................................... 2
1.2.1 Photovoltaic concentrator .......................................................................... 3
1.2.2 Solar tracker............................................................................................... 5
1.2.3 Inverter ...................................................................................................... 7
1.3 Literature Review for Wind Effects on Solar Tracker Structure ........................... 8
1.4 Purpose and Scope .............................................................................................. 10
2. MODELING................................................................................................................ 12
2.1 Modeling for Wind Loads ................................................................................... 12
2.1.1 Finite element model ............................................................................... 12
2.1.2 Physical properties and boundary conditions .......................................... 13
2.2 Modeling for Structural Deformation.................................................................. 14
2.2.1 Finite element model ............................................................................... 14
2.2.2 Material properties................................................................................... 15
2.2.3 Loading and boundary conditions ........................................................... 15
2.3 Investigated Cases ............................................................................................... 17
2.4 Definition of Misalignment of Solar Radiation................................................... 17
3. DEFORMATION MEASUREMENT......................................................................... 19
3.1 Experimental Setup ............................................................................................. 19
3.2 Investigated Cases and Experimental Procedure ................................................ 19
4. RESULTS AND DISCUSSION.................................................................................. 21
4.1 Effect of Weight Only ......................................................................................... 21
4.2 Effect of Wind Loads .......................................................................................... 26
5. CONCLUSIONS......................................................................................................... 32
REFERENCES.................................................................................................................... 33
TABLES .............................................................................................................................. 36
FIGURES ............................................................................................................................ 37

1. D. Y. Goswami, F. Kreith, and J. F. Kreider, Principles of Solar Engineering, 2nd Ed., Taylor & Francis, Philadelphia, PA, USA, 1999.
2. R. A. Messenger and J. Ventre, Photovoltaic Systems Engineering, 2nd Ed., CRC Press, Boca Raton, FL, USA, 2003.
3. J. S. Hsieh, Solar Energy Engineering, Prentice-Hall Inc., Englewood Cliffs, NJ, USA, 1986.
4. A. Goetzberger and V. U. Hoffmann, Photovoltaic Solar Energy Generation, Springer, Berlin, Germany, 2005.
5. T. Markvart and L. Castaňer, Solar Cells: Materials, Manufacture and Operation, Elsevier Ltd., Oxford, UK, 2005.
6. A. Luque and S. Hegedus, Handbook of Photovoltaic Science and Engineering, John Wiley & Sons Ltd., West Sussex, England, 2003.
7. R. R. King, D. C. Law, K. M. Edmondson, C. M. Fetzer, F. S. Kinsey, H. Yoon, R. A. Sherif, and N. H. Karam, “40% Efficient Metamorphic GaInP/GaInAs/Ge Multijunction Solar Cells,” Applied Physics Letters, Vol. 90, 2007, pp. 183516-1-183516-3.
8. A. Luque, G. Sala, and I. L.-Heredia, “Photovoltaic Concentration at Onset of its Commercial Deployment,” Progress in Photovoltaics: Research and Applications, Vol. 14, 2006, pp. 413-428.
9. G. Willeke, “High Concentration Photovoltaic–State-of-the-art and Novel Concepts,” pp. 2841-2844 in Proceeding of the 3rd World Conference on Photovoltaic Energy Conversion, May 11-18, Osaka, Japan, 2003.
10. A. L. Luque and V. M. Andreev, Concentrator Photovoltaics, Springer, Berlin, Germany, 2007.
11. K. Araki, “500X to 1000X–R&D and Market Strategy of Daido Steel,” in Proceeding of the 4th International Conference on Solar Concentrators for the Generation of Electricity or Hydrogen, March 12-16, San Lorenzo del Escorial, Spain, 2007.
12. K. Ryu, J.-G. Rhee, K.-M. Park, and J. Kim, “Concept and Design of Modular Fresnel Lenses for Concentration Solar PV System,” Solar Energy, Vol. 80, 2006, pp. 1580-1587.
13. A. Sarno, F. Apicella, M. Pellegrino, C. Privato, and F. Roca, “Enea’s Experience on the PV-Concentrators Technology: the PhoCUS Project,” in Proceeding of the 4th International Conference on Solar Concentrators for the Generation of Electricity or Hydrogen, March 12-16, San Lorenzo del Escorial, Spain, 2007.
14. P. Gleckman, “A High Concentration Rooftop Photovoltaic System,” in Proceeding of the SPIE-The International Society for Optical Engineering, August 26-28, San Diego, CA, USA, 2007.
15. K. Nishioka, T. Takamoto, T. Agui, M. Kaneiwa, Y. Uraoka, and T. Fuyuki, “Evaluation of InGaP/InGaAs/Ge Triple-Junction Solar Cell and Optimization of Solar Cell’s Structure Focusing on Series Resistance for High-Efficiency Concentrator Photovoltaic Systems,” Solar Energy Materials and Solar Cells, Vol. 90, 2006, pp. 1308-1321.
16. C. Baur, A. W. Bett, F. Dimroth, G. Siefer, M. Meusel, W. Bensch, W. K?stler, and G. Strobl, “Triple-Junction III-V Based Concentrator Solar Cells: Perspective and Challenges,” Journal of Solar Energy Engineering, Transactions of the ASME, Vol. 129, 2007, pp. 258-265.
17. F. R. Rubio, M. G. Ortega, F. Gordillo, and M. L?pez-Mart?nez, “Application of New Control Strategy for Sun Tracking,” Energy Conversion and Management, Vol. 48, 2007, pp. 2174-2184.
18. I. L.-Heredia, P. H. Magalh?es, G. Qu?m?r?, R. Cervantes, J. M. Moreno, and O. Laurent, “CPV Tracking system: Performance Issues, Specifications and Design,” in Proceeding of the 4th International Conference on Solar Concentrators for the Generation of Electricity or Hydrogen, March 12-16, San Lorenzo del Escorial, Spain, 2007.
19. P. Roth, A. Georgiev, and H. Boudinov, “Cheap Two Axis Sun Following Device,” Energy Conversion and Management, Vol. 46, 2005, pp. 1179-1192.
20. N. H. Helwa, A. B. G. Bahgat, A. M. R. E. Shafee, and E. T. E. Shenawy, “Maximum Collectable Solar Energy by Different Solar Tracking Systems,” Energy Sources, Vol. 22, 2000, pp. 23-34.
21. H. Lerchenm?ller, A. Hakenjos, I. Heile, B. Burger, and O. Stalter, “From FLATCON Pilot Systems to the First Power Plant,” in Proceeding of the 4th International Conference on Solar Concentrators for the Generation of Electricity or Hydrogen, March 12-16, San Lorenzo del Escorial, Spain, 2007.
22. I. L.-Heredia, C. Martin, M. T. Ma?anes, J. M. Moreno, J. L. Auger, V. Bodin, J. Alonso, V. Diaz, and G. Sala, “A Subdegree Precision Sun Tracker for 1000X Microconcentrator Modules,” pp. 857-860 in Proceeding of the 3rd World Conference on Photovoltaic Energy Conversion, May 11-18, Osaka, Japan, 2003.
23. J. A. Peterka, Z. Tan, J. E. Cermak, and B. Bienkiewicz, “Mean and Peak Wind Loads on Heliostats,” Journal of Solar Energy Engineering, Transactions of the ASME, Vol. 111, 1989, pp. 158-164.
24. I. L.-Heredia, G. Qu?m?r?, P. H. Magalh?es, A. F. de Lerma, L. Hermanns, E. de Alarc?n, and A. Luque, “Modelling Structural Flexure Effects in CPV Sun Trackers,” pp. 2105-2109 in Proceeding of 21st European Photovoltaic Solar Energy conference, September 4-8, Dresden, Germany, 2006.
25. C. Cancro, G. Graditi, G. Leanza, F. Pascarella, A. Sarno, and D. Mancini, “Field Testing of the PhoCUS Solar Tracker by Means of a Novel Optoelectronic Device,” in Proceeding of the 4th International Conference on Solar Concentrators for the Generation of Electricity or Hydrogen, March 12-16, San Lorenzo del Escorial, Spain, 2007.
26. “Meshing,” Chapter 5 in COMSOL Multiphysics User’s Guide V3.4, COMSOL AB, Stockholm, Sweden, 2007.
27. “Structural Elements,” Chapter 14 in ABAQUS Analysis User’s Manual V6.5, ABAQUS, Inc., Providence, RI, USA, 2004.