2-kW級太陽追蹤器結構變形與追日偏差分析

本研究主旨在利用有限元素分析法(FEA)，探討一組2-kW級太陽光電系統之太陽追蹤器受到重力及風力作用下，其結構變形和PV模組的追日偏差量。分析的條件分別為無風之自重狀態，以及在風速為7 m/s、12 m/s和37.5 m/s之情況，在每個風速作用下又各別分為風從太陽追蹤器的正面(0o)至背面(180o)，以30o為一間隔吹來之七種風向；而在風速37.5 m/s的作用下，太陽追蹤器停止運作並以仰角0o插上安全插銷作為分析條件。此外，本研究亦分析此太陽追蹤器之自然振動頻率作為設計及安裝參考，避免結構共振之發生。同時藉由量測此太陽追蹤器二個選定位置在實際操作情況下之應變變化，與模擬結果作比對，以驗證本研究所建立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，可適用於分析太陽光電系統之結構變形。根據von Mises破損準則，模擬結果顯示此太陽追蹤器在受到重力加上風速為7 m/s、12 m/s或37.5 m/s的作用下，預期各個組件將不會有永久變形之情形發生。模擬結果亦顯示此追蹤器在不同追日角度受重力及不同風力作用下，PV模組追日偏差量的變化趨勢與其總位移的變化趨勢一致。此外，產生較大追日偏差量的PV模組皆位於受風前緣面板中的一個。除了在風速37.5 m/s的作用下，在其他所有分析情況中，PV模組在風速為12 m/s並從其正面(0o)吹來的情況下會有最大的追日偏差量，其值為1.48o。由於此偏差角對於此PV模組發電效率影響很小，所以預期此太陽追蹤器在風速為12 m/s的作用下仍可以正常運作，不會有明顯的發電效率下降，同時在正常的運作之下，不會有結構破損之情形發生。自然振動頻率分析結果顯示其前六個振動模態的自然頻率值落在3.85 Hz至11.4 Hz之間，未來在架設此太陽追蹤器時應考慮所在地之風場的頻率。

關鍵字

偏差角；太陽光電；太陽追蹤器；結構變形

並列摘要

The purpose of this study is using finite element analysis (FEA) to investigate the effects of gravity and wind loadings on the structural deformation and misalignment of solar radiation in a 2-kW photovoltaic (PV) system. Several loading conditions, including gravity alone and gravity plus wind speeds of 7 m/s, 12 m/s, and 37.5 m/s with blowing direction varying from front (wind direction of 0o) to back (wind direction of 180o) sides with an interval of 30o, are applied to calculate the stress distribution and structural deformation. The misalignment of solar radiation induced by structural deformation is calculated. Moreover, to avoid the damage caused by resonance, natural frequencies of vibration for the given PV system are also determined. A comparison of the simulation and measurement results of strain change at two selected locations in the given solar tracker during field operation is made to validate the constructed FEA model. A reasonable agreement of the simulation and measurement results is found such that the constructed FEA model is validated to be effective in assessment of the structural integrity of a PV system. No structural failure is predicted for all components in the given solar tracker under all of the given loading conditions according to the von Mises failure criterion. An agreement in the trend of variation of misalignment and resultant displacement of PV modules is found. Moreover, the maximum misalignment for each wind direction occurs at the PV modules which touch the wind first. Considering the effects of gravity and wind speeds of 7 m/s and 12 m/s, the maximum misalignment of solar radiation is of 1.48o for a wind speed of 12 m/s with wind direction of 0o. It is expected that such a misalignment value will not cause a significant degradation of power generation for the given PV system. Consequently, the given PV system can operate safely under the effects of gravity and wind speeds of 7 m/s and 12 m/s with a good efficiency. The range of natural frequencies of the first six vibration modes for the given PV system is from 3.85 Hz to 11.4 Hz.

並列關鍵字

deformation ； structural ； photovoltaic ； solar tracker ； misalignment

參考文獻

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國際替代計量

2-kW級太陽追蹤器結構變形與追日偏差分析

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