單軸追日太陽光電系統的最佳發電控制研究

Abstract

本研究旨在探討適應於各種安裝環境的單軸追日太陽光電系統最佳發電控制技術。 最佳發電追蹤控制係定期搜尋不同停駐角度的發電量，找尋最佳停駐角，並進行定位控制，以提升太陽光電系統的發電量，降低各種環境因素影響（例如：遮陰、折射、反射、散射等…）所導致的發電效率下降。 前人的單軸三角度追日太陽光電系統長期測試結果顯示，輻射量愈高，發電量提升效果愈顯著（與固定式相比），在台北地區發電量平均提升25%。但是，若單軸三角度追日太陽光電系統安裝場地有建築物遮陰，長期實測結果顯示平均損失21%的總發電量，而晴天的單日總發電量損失可高達40%。 同樣太陽光電系統如改用本研究的單軸最佳控制技術，測試結果顯示，晴天時停駐角會在太陽輻射入射量和遮陰間取得平衡，自動搜尋到最大發電量的停駐角度位置，而陰天則會因為雲層漫射追蹤到水平位置。長期測試的平均遮陰損失約10%，有明顯改善，證明比單軸三角度追日更能夠應付安裝環境的考驗。

The main purpose of this thesis is to develop a maximum-power generation control of single-axis sun tracking PV system to overcome the environmental effect such as shading, building orientation etc. Former studies on one-axis three-position sun tracking PV (1A-3P) has shown that the overall PV energy generation can increase 25% in Taipei. But the loss due to shading can be as high as 21% in long-term overall performance, or 40% in a single-day performance. The present study develops a single-axis maximum-power generation technique (1A-MPG) which tracks the sun for best stopping angle every hour. The long-term test results show that the overall shading loss is reduced to 6.2% from 25% in 1A-3P, or reduced to 17.5% from 42.7% in 1A-3P in single-day performance. The optimal stopping angle is +30°~ +40°in the morning, and +25°~ -25°at noon, and -30°~ -40°in afternoon.