This paper presents the design of a decentralized proportional–integral (PI) controller for a wastewater treatment plant (WWTP). The aeration rate and the return recycle sludge rate are manipulated inputs to the WWTP process, while substrate and biomass concentration are considered as the output variables. The study is divided into two segments: A decentralized controller is designed based on the best pairing in the first segment, and in the second segment, a decoupler is developed to reduce the interactions. Decouplers are generally used to create independent loops in the multivariable control loops. Each decoupled subsystem is converted to first order plus time delay (FOPTD) model using a system identification toolbox to design independent diagonal controllers. The numerical simulations have been performed to evaluate the effectiveness of the presented methods. Furthermore, a robustness study has also been carried out by taking into account multiplicative input and output uncertainties, and it is found that the controller designed based on minimizing the integral of absolute error (IAE) criteria shows more robust.

中文翻译：

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活性污泥过程的鲁棒分散比例-积分控制器设计

本文介绍了废水处理厂（WWTP）的分散比例积分（PI）控制器的设计。曝气速率和回流污泥速率是污水处理厂工艺的受控输入，而底物和生物质浓度则视为输出变量。该研究分为两个部分：基于第一部分中的最佳配对设计了分散式控制器，而在第二部分中，开发了去耦器以减少相互作用。解耦器通常用于在多变量控制回路中创建独立回路。使用系统识别工具箱设计独立的对角线控制器，将每个解耦的子系统转换为一阶加时间延迟（FOPTD）模型。进行了数值模拟以评估所提出方法的有效性。此外，还通过考虑乘法输入和输出的不确定性进行了鲁棒性研究，发现基于最小化绝对误差积分（IAE）标准设计的控制器显示出更高的鲁棒性。