基于有限时间扰动观测器的水厂加矾系统二阶滑模控制

Second-order sliding mode control based on finite-time disturbance observer for alum dosing system of water plant

水厂絮凝沉淀过程具有强非线性、不确定性和参数时变等特点,并且原水水质和水量突变等扰动容易对絮凝沉淀过程造成不利影响.本文提出了一种基于有限时间扰动观测器的加矾系统二阶滑模控制设计方法.首先,文章采用带有非光滑项的二阶滑模控制方法设计加矾系统反馈控制;然后,文章设计有限时间扰动观测器对原水水质和水量突变等扰动,以及絮凝沉淀过程强非线性、不确定性和参数时变等导致的模型不匹配进行估计,估计结果作为前馈补偿与反馈控制相结合;最后,理论分析证明了基于有限时间扰动观测器的二阶滑模控制方法的稳定性.仿真结果表明,本文所提出的复合控制方法有效提升了加矾系统的鲁棒性和抗扰动性能.

The flocculation and sedimentation process of water plant has the characteristics of strong nonlinearity,uncertainty and time-varying parameters,and disturbances of sudden changes in raw water quality and water flow are easy to adversely affect the flocculation and sedimentation process.This paper proposes a control design method of secondorder sliding mode based on the finite-time disturbance observer for alum dosing system.First,the feedback control of alum dosing system is designed by second-order sliding mode control method with non-smooth terms.Then,a finitetime disturbance observer is designed to estimate disturbances of sudden changes in raw water quality and water flow,as well as model mismatch caused by strong nonlinearity,uncertainty,and time-varying parameters in the flocculation and sedimentation process.The estimation result is combined with feedback control as feedforward compensation.Finally,the theoretical analysis proves the stability of second-order sliding mode control method based on the finite-time disturbance observer.The simulation results show that the composite control method proposed in this paper effectively improves the robustness and anti-disturbance performance of alum dosing system.