Research On Automatic Coagulant Dosage In Water Treatment Based On LonWorks And Predictive Control

In the process of drinking water purification which is mainly supplied by surface water, coagulation is an indispensable course, turbidity removal and clarification are the main purpose of water treatment. Under certain conditions, the amount of coagulant dosage directly determines the coagulation effect. Consequently, the actualization of optimal control on the amount of coagulant dosage is urgent requirement for the assurance of water quality and the economization of operation costs of the waterworks.At present, the measuring instruments used in domestic process of coagulant dosage are of poor quality generally and the accuracy and the reliability cannot meet the control requirement. The great delay time of the process of coagulant dosage and difficulty of establishing accurate model bring a lot of difficulties for custom PID control. The predictive control which adopts control strategies of multi step-forecast, rolling optimization and feedback compensation, has good control effect and great robustness, and is acceptable for the industrial process which is hard to establish accurate mathematical model and very complicated.Firstly, this paper utilizes least square method to establish the mathematical model of coagulation system, then introduces the DMC algorithm of predictive control, derives the IMC structural diagram of DMC , and analyzes DMC system performance. System performance is simulated by MATLAB/SIMULINK. This paper solves the problem of output oscillation and proves the validity and feasibility of the application of the algorithm by properly setting control parameters and designing feedback filter. Performance of DMC algorithm and PID algorithm are compared and the superiority of DMC algorithm is proved.This paper is dedicated to design the coagulant dosage node, because the spread of this paper is to establish automatic system of waterworks, LonWoks technology is selected to design the node. Products developed by LonWorks have the characteristics of openness and interoperability , and the products which are acceptable for remote monitoring are digital and net-based .Based on the complexity of the control program and variety of sample data , this paper proposes host-based node, singlechip AT89C52 is selected to actualize...