本研究以擬譜法(Pseudo-spectral method)解決水力發電中常面臨之最佳化控制問題,以最低經濟成本為目標,創造最高效益的抽蓄式水庫水力發電系統。台灣由於乾溼季節明顯,雨量分配不均且因地形條件儲水不易,故必須思考如何在有限的土地創造高效益的水資源利用,加上須考量節能減碳的目標,其水庫水力發電的最佳化控制問題常常是高維度且多變量,又由於高維度的非線性問題很難獲得最佳化控制問題的解析解,多需選擇數值方法進行處理。故本研究使用效率佳的數值方法-擬譜法來解決複雜的最佳化控制問題。 擬譜法為一新興之數值分析方法,配合其解題會使用到Chebyshev及Legendre兩類正交函數集以選取節點,而本研究採用Legendre polynomials,再由Lagrang polynomials根據其節點描繪不同函數,並結合離散後的狀態變數及控制變數,以處理原問題,即可繪出其最佳化問題型式。在多目標的最佳化規劃中,以擬譜法處理能有效離散難以計算的高階函數,便於處理最佳化控制問題。
Optimal control is a mathematical optimization problem and optimal control problems seek optimal control design subjective to a system of differential equations. Because of the nonlinearity of problems, it is hard to derive the analytic solutions for optimal control problem. Hence, the research uses an efficient numerical method, pseudo-spectral method, to solve complex optimal control problem. The design of the algorithm is based on using the pseudo-spectral differentiation matrix to reduce a high-dimensional function to low-dimensional functions, and the low-dimensional functions are more possible to solve difficult optimization problems. The reservoirs generate electricity constantly is built on the basis of steady inflow, but Taiwan's reservoirs unable to provide a stable amount of water. So designing a mathematical model of optimal control is used to deploy water distribution ratio for hydropower of wet and dry seasons. Because of the hydrological and geographical conditions in water resources systems in Taiwan, unstable water flow is hard to provide steady hydropower generation. An optimal control problem of hydropower generation is formulated for water resources system. A case study of Taiwanese water resources system is conducted. This study use monthly rainfall and output hydropower data to analysis the maximum hydropower with steady outflow. The results show the optimal control of water management and hydropower generation.