基于多目標粒子群優化的污水處理系統自適應評判控制
Adaptive critic control for wastewater treatment systems based on multiobjective particle swarm optimization
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摘要: 考慮到城市污水處理系統存在保證出水水質達標和降低能耗的需要, 將其運行過程視為一個多目標優化控制問題. 針對此問題, 提出一種基于多目標粒子群優化(Multi-objective particle swarm optimization, MOPSO)算法的污水處理系統自適應評判控制方案, 該方案分為上層優化和底層跟蹤控制兩部分. 首先, 污水處理過程存在非線性、多變量、大時變等特點, 結合數據驅動思想對入水及出水組分數據進行分析, 構建關于出水水質和運行能耗的多目標優化模型. 采用徑向基函數(Radial basis function, RBF)神經網絡進行建模, 并與反向傳播(Back propagation, BP)神經網絡進行了對比. 然后, 結合MOPSO算法強大的優化能力, 采用MOPSO算法對優化目標進行求解, 并設計一個決策方式從最優解集中選出偏好解, 作為溶解氧與硝態氮濃度的最優設定值. 接下來, 底層跟蹤控制部分采用基于自適應動態規劃的輔助控制器對比例–積分–微分算法的控制策略進行補充, 彌補了傳統控制算法自適應能力差的不足. 此外, 比例–積分–微分算法也為自適應動態規劃算法提供了初始的穩定控制策略,克服了學習算法前期控制效果差的缺陷,保證了污水處理過程的安全性和可靠性. 最終, 該控制器成功實現了對最優設定值的跟蹤控制. 將所提算法在污水處理基準仿真平臺上進行驗證, 結果表明所提算法能有效地提高污水處理過程的運行性能, 不僅能保證出水水質達標, 同時能有效地降低污水處理過程產生的能耗.Abstract: Given the need to ensure that effluent quality meets the standards and reduces energy consumption in urban wastewater treatment systems, the operation process is considered a multiobjective optimization control problem. An adaptive critic control scheme is developed based on multiobjective particle swarm optimization. This scheme is divided into two parts: upper optimization and bottom tracking control. First, considering the characteristics of nonlinear, multivariable, and large time variation in a wastewater treatment system, the mechanism model is difficult to establish accurately. To preserve quality and reduce consumption, an accurate operation index model of the wastewater treatment process must be designed. The data of the inlet and outlet components are analyzed using a data-driven framework. A multiobjective optimization model reflecting effluent quality and energy consumption is constructed. A radial basis function neural network is used for modeling and compared with a back-propagation neural network. Then, combined with powerful optimization capabilities, the multiobjective particle swarm optimization algorithm is used to solve the multiobjective optimization problem. Combining the practical importance of the two indicators of energy consumption and water quality, a decision method is designed to select the preferred solutions from the optimal solution set. The preferred solutions can be defined as the optimal set concentrations of dissolved oxygen and nitrate nitrogen. Next, the bottom tracking control part adopts an auxiliary controller based on adaptive dynamic planning to supplement the control strategy of a proportional–integral–derivative algorithm, compensating for the shortcomings of the poor adaptive ability of the traditional control algorithm. In addition, this proportional–integral–differential algorithm provides an initial stable control strategy for the adaptive dynamic programming algorithm, overcoming the poor control effect of the learning algorithm in the early stage and ensuring the safety and reliability of the wastewater treatment process. Ultimately, the controller successfully achieves the tracking control of the optimal setting value. To verify the optimization effect and control performance of the proposed scheme, we use benchmark simulation model no. 1 to complete the simulation. Using the indicators of water quality and energy consumption, we also compare the proposed scheme with other multiobjective optimization schemes. The results show that the proposed algorithm effectively improves the operational performance of the wastewater treatment process. It not only ensures that the effluent water quality meets the standards but also effectively reduces the energy consumption of wastewater treatment.