太陽能發電系統遭遇遮蔽效應下之複合式最大功率點追蹤器之研製

Design and Implementation of a Hybrid Maximum Power Point Tracker in Solar Power System under Partially Shaded Conditions

唐丞譽(Cheng-Yu Tang)

指導教授 ： 歐勝源

國立臺北科技大學/電資學院/電機工程系研究所/碩士(2012年)

摘要

太陽能發電系統之陣列遭遇雲層、樹木、建築物等之陰影遮蔽時，其功率-電壓特性曲線會產生多重峰值之現象，一般稱為遮蔽效應。傳統最大功率追蹤法則在遮蔽效應下可能無法追蹤到最大功率之峰值，使太陽能陣列無法達到最大發電利用率而造成能量損失。
本論文提出遮蔽效應下之新型複合式最大功率追蹤演算法。在系統剛啟動時先利用直流-直流轉換器之責任週期由小至大以固定間隔開啟，藉以掃描遮蔽效應下多重峰值之功率-電壓特性曲線並且判斷出功率最大值，文中稱之為SD法則。接著啟動擾動觀察法進行追蹤以達到遮蔽效應下之真正最大功率點。此外，SD法所得到之功率點已很接近最大功率，此時可將擾動觀察法之擾動量設定很小以達到系統精確度與降低傳統擾動觀察法在最大功率點振盪之現象。本論文研製100W升壓型轉換器做為最大功率追蹤器之硬體架構，並且使用TMS320F2812數位訊號處理器以實現本文之複合式演算法。最後以實驗結果驗證本論文所提出之複合式最大功率追蹤演算法，無論是否發生遮蔽效應皆可精準且迅速追蹤到太陽能陣列之實際最大功率點，克服變化莫測之天候狀況而提升太陽能發電系統利用率。

關鍵字

太陽能電池 ； 遮蔽效應 ； 最大功率點追蹤 ； 升壓型轉換器 ； 擾動觀察法 ； SD法則

並列摘要

Power-voltage characteristics of photovoltaic (PV) arrays will be shaped by multiple steps and peaks due to the shadow of clouds, trees, or buildings, which is called partially shaded conditions (PSC). Conventional maximum power point tracking methods can not track the real maximum power point (MPP) actually, causing the reduction of array utilization and the losses of energy.
In this thesis, a novel hybrid maximum power point tracking (MPPT) method under PSC is proposed. The duty cycle of the dc-dc converter is controlled from small to large with fixed intervals in order to scan the P-V characteristics curve under partially shaded conditions, and then find out the maximum power value, which is called SD algorithm in this thesis. With the proposed control algorithm, as soon as the SD process is finished, the perturbation and observation (P&O) method immediately starts so as to track the real MPP under PSC. In addition, the value of perturbation can be set as small as possible in order to achieve high tracking accuracy and decrease the oscillation phenomenon causing by conventional P&Q method because the tracked point after using SD process is very close to the real MPP. The digital signal processor (DSP) TMS320F2812 from TI is used to implement the proposed control method in a Boost converter which is utilized to act as the power converter topology. Finally, experimental results confirm the proposed maximum power point tracking method that can accurately and promptly track the real MPP of PV arrays even under PSC, overcoming unpredictable weather conditions and rising up the utilization of PV arrays.

並列關鍵字

Photovoltaics ； Maximum power point tracking ； Boost converter ； Perturbation and observation method ； Partially shaded conditions(PSC) ； SD algorithm

參考文獻

[21]J. A. Jiang, T. L. Huang, Y. T. Hsiao and C. H. Chen, “Maximum power tracking for photovoltaic power systems,” Tamkang Journal of Science and Engineering, vol. 8, no 2, pp. 147-153, 2005.

[34]蘇郁珺，用於太陽能發電系統之複合式最大功率追蹤器的研製，碩士論文，台北科技大學電機所，2010。

[28]陳昀瑞，新型複合式最大功率追蹤演算法之設計與實現，碩士論文，台北科技大學電機所，2011。

[1]UNITED NATIONS, “Kyoto protocol to the united nations framework convention on climate change,” 1998.

[2]Pew Charitable Trusts, http://www.pewtrusts.org/.