本研究目的在透過有限元素分析(FEA)，計算一組1.5-kW級聚光型太陽光電系統(HCPV)之太陽追蹤器受到重力及不同風力作用時，其應力分佈、結構變形和聚光模組的追日偏差量。考慮的負荷條件分別為無風之自重狀態，以及風速7 m/s、12 m/s及37.5 m/s之情況，每個風速又各別分為七個風向，從太陽追蹤器的正面(0o)至背面(180o)，以30o為一間隔；在風速37.5 m/s的作用下，僅考慮追蹤器停止運作之仰角0o插上安全插銷作為分析條件。另外，為避免結構共振發生，本研究亦分析此HCPV系統之自然振動頻率作為設計與安裝參考。為驗證本研究所建立有限元素分析模型之有效性，選定此太陽追蹤器二個位置量測在無風實際操作情況下之應變變化，與模擬結果作比對。FEA模擬結果之應變改變趨勢和實驗結果相符，此一致性確認此有限元素分析模型應用於分析聚光型太陽光電系統結構變形之有效性。此外，為了驗證本研究所建立風場模型之有效性，將模擬結果與前人風洞實驗的結果作比對，模擬結果之壓力係數改變趨勢和實驗結果一致，證實本研究所建立風場模型之有效性，可適用於評估各種風速條件作用於太陽追蹤器之影響。
應力分析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的作用下，各個組件將不會有永久變形之情形發生。然而，在風速37.5 m/s的作用下，追蹤器在某些風向，某個主柱零件中的最大應力值將大於其降伏強度，預期會發生塑性變形。為改善此情況，於太陽追蹤器主柱之組件加上導角的設計以及增加補強肋的厚度後，可有效降低其組件之應力集中因素的影響，並提升此組件之安全係數，避免塑性變形產生。考慮此HCPV系統在正常作動下，在風速為12 m/s並從背面(150o和180o)吹來的情況下，會導致聚光透鏡有最大的追日偏差量，其值約為0.493o或0.494o。此數值小於此聚光模組的可接受角度0.5o，所以預期此HCPV系統在風速為12 m/s的作用下仍有良好的發電效率，且不會有結構塑性變形的情形發生。自然振動頻率分析結果顯示其前三個振動模態的自然頻率值介於4.3 Hz至5.66 Hz之間，第四個到第六個振動模態的自然頻率值則落在10.78 Hz至16.4 Hz之間，未來在架設此太陽追蹤器時應考慮所在地之風場頻率，以避免共振現象之發生。

The aim of this work is using finite element analysis (FEA) to study the effects of gravity and wind loadings on the structural deformation and concentrator misalignment in a 1.5-kW high concentrator photovoltaic (HCPV) system. Several loading conditions are considered, including gravity alone and gravity plus wind speeds of 7 m/s, 12 m/s, and 37.5 m/s with various blowing directions from front side (wind direction of 0o) to back side (wind direction of 180o) with an interval of 30o. For safety reason, the concentrator array is placed at elevation angle of 0o and the safety pins are locked to protect the HCPV system under wind speed of 37.5 m/s. The concentrator misalignment induced by structural deformation is also calculated except for wind speed of 37.5 m/s. Natural frequencies of vibration for the given HCPV system are also determined to avoid resonance. Experimental measurements of strain change at two selected locations in the given solar tracker under a windless operation condition are compared with the simulations to validate the constructed FEA model. The simulations and experimental results are in a good agreement such that the constructed FEA model is validated to be effective in assessing the structural integrity of an HCPV system. Moreover, in order to validate the constructed CFD model, a benchmark exercise is performed to make a comparison of the simulations with previous experimental results. The variation trends of pressure coefficient in simulation agree well with those in experiment such that the constructed CFD model is validated. Therefore, the constructed CFD model is effective in assessing the wind loadings acting on a solar tracker.
As the calculated maximum stress is less than the yield stress of material, no structural failure is predicted for all the components in the given solar tracker under the loading conditions of gravity alone and plus a wind speed of 7 or 12 m/s. However, the maximum von Mises equivalent stress in the main column of the given solar tracker is larger than the yield stress for wind speed of 37.5 m/s such that a structural plastic deformation is predicted. An improved chamfer design with an enlarged thickness of the enhanced ribs in the main column effectively reduces the stress concentration effect and increases the safety factor to a reasonable value. For the given HCPV system subjected to gravity and wind speeds of 7 m/s and 12 m/s, the maximum concentrator misalignment is of about 0.493o and 0.494o under a wind speed of 12 m/s with wind directions of 150o and 180o, and it is within the range of an acceptance angle of 0.5o. The given HCPV system is thus expected to operate safely under the effects of gravity and wind speeds of 7 m/s and 12 m/s with a good efficiency. The calculated natural frequencies of the first three vibration modes for the given HCPV system are in the range of 4.3 Hz to 5.66 Hz. The range of natural frequencies for the fourth mode to the sixth mode is between 10.78 Hz and 16.4 Hz. To avoid damage caused by resonance, the natural frequencies of the given HCPV system have to be considered in selection of installation site.

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