污水活性污泥处理过程的溶解氧增益调度控制

Gain-Scheduling Control of Dissolved Oxygen Concentration in Activated Sludge Wastewater Treatment Processes

考察污水活性污泥处理过程溶解氧控制效果的重要性能指标是溶解氧浓度的波动情况和能耗;针对溶解氧的非线性传递模型,提出了以溶解氧设定值作为调度变量的溶解氧增益调度控制方法;在溶解氧设定值处进行泰勒级数展开得到线性模型以此来近似在该设定值处的非线性系统,再采用线性控制系统的优化设计方法 (如参考模型方法)设计控制器,得到一簇空间离散的线性时不变控制器;控制系统运行时,根据不同的调度值(溶解氧设定值),调度线性时不变控制器,从而实现溶解氧的非线性控制;最后对污水活性污泥处理过程的溶解氧控制进行了仿真,模型参数来源于实际污水厂数据,仿真结果表明,文章提出的增益调度控制方法无论在能耗方面还是在控制精度方面都要明显优越于常规的开关控制和PID控制。

Dissolved oxygen （DO） concentration has long been recognized as a important controlled variable in the activated sludge wastewater treatment processes, and the fluctuation of DO concentration around the set--point and accumulated air consumption are taken as important performance parameters. The gain--scheduling control methods for DO concentration nonlinear model, where set--point value for DO concentration is considered as a scheduled variable, is presented, In the presented methods, the linear model is obtained by the expansion of Taylor series around the set point to approximate the nonlinear system at this set point, and then the optimal control tnethod of linear sys- tem （such as reference model methods） is used to obtain a cluster of linear time invariant controllers. In the operation of the control system, the linear time invariant controller is scheduled according to the different scheduling values （the set point values of dissolved oxygen）. Final- ly, the control of dissolved oxygen in activated sludge process was simulated, where the model parameters are derived from a actual wastewater treatment process, and the simulation result show that the presented gain--scheduling control method has obvious advantages o- ver conventional control methods such as On--Off control and PID control in the energy consumption and control precision.