| At present,the sewage treatment project has become more and more important to the social development.The traditional sewage treatment technology is mainly manual and conventional instrument control.Relying on the experience of workers,the treatment quality is unstable and the productivity is low.In order to improve the efficiency of sewage treatment,this paper selects advanced automatic control technology and equipment to design the automatic control system of sewage treatment plant.Based on the actual situation of a sewage plant,this paper analyzes the actual process flow of sewage,and determines the design requirements of the control system according to the characteristics of the process flow.In view of the nonlinear and multivariable characteristics of sewage treatment,the master-slave control system is composed of industrial Ethernet PROFINET and PROFIBUS-DP bus.On the basis of determining the overall control scheme,the hardware design and software design of the control system are carried out.The hardware design adopts the form of IPC + PLC + substation,and selects the type of PLC module,field instruments and other hardware equipment.The software design includes three parts: the upper computer monitoring screen design,PLC programming and touch screen interface development.Use Win CC software to realize the upper computer interface development;use step 7 programming environment to complete the hardware configuration and program design of Siemens S7-300 PLC;use Win CC flexible 2008 software to realize the touch screen picture development.In order to realize the accurate control of acid-base neutralization reaction,the cascade PID control strategy is adopted.And the cascade PID control model is simulated by Matlab / Simulink.The experimental results verify the superiority of the control algorithm.The design realizes the automatic monitoring of the domestic sewage treatment system,which can meet the needs of the modern society for the automatic control of sewage treatment. |
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