Research On Optimal Control Method Of Dissolved Oxygen Concentration In Sewage Treatment Process

In the process of sewage biochemical treatment,the dissolved oxygen concentration is an important component that determines the quality of the effluent water.Too high or too low will have a greater impact on the sewage treatment effect.It can intuitively and quickly reflect the operation of the entire process The situation can also directly affect the effect of sewage treatment and system energy consumption.The control difficulty is that the sewage treatment process involves cumbersome biochemical reactions,resulting in the characteristics of large time-varying,strong coupling and nonlinearity of dissolved oxygen concentration control.Many conditions,such as fluctuations in inlet flow rate and changes in pollutant concentration,have produced many unmeasured interference factors.These conditions will increase the uncertainty of the system.Conventional control methods are difficult to achieve the desired control effect.The activated sludge method of sewage treatment process is the research object.On the basis of in-depth analysis of the mechanism of the process,a simplified model of activated sludge number is established to study the optimal control method of dissolved oxygen concentration in the biochemical process of sewage treatment.It provides technical guarantee for the global optimization of energy saving and consumption reduction in the production process of sewage treatment.Based on the above goals,the main research contents completed in this paper are:First of all,this paper analyzes the process mechanism of the activated sludge process in detail,and studies the relationship among the components,reaction process,stoichiometric constants and kinetic parameters of the activated sludge model,and at the same time,the process Reasonable simplification has established a systematic mathematical model,which has laid a theoretical foundation for subsequent research.Secondly,the principle and characteristics of internal model control are introduced,and its advantages and disadvantages are analyzed.In view of the shortcomings,a two-degree-of-freedom internal model control is proposed.A two-degree-of-freedom internal model controller is designed.In view of its advantages and disadvantages,the filter parameters of its controller are unchanged,and when the controlled model does not match,the performance of the system is insufficient.A rule-layer neuron that uses neuron activity and activation intensity to dynamically increase or decrease the fuzzy neural network The method dynamically adjusts the filtering parameters,designs an improvedfuzzy neural network two-free internal model controller,and performs a comparative simulation analysis to verify the rationality of using this control method to control the concentration of dissolved oxygen in the sewage biochemical treatment process.Once again,the structure,characteristics and key parameter information of the BSM1 benchmark simulation platform are introduced,and the structure and working characteristics of the biochemical reaction tank model and the secondary settling tank model and the dynamic characteristics of water inflow are analyzed.To evaluate the standard and build a sewage treatment process simulation platform using MATLAB,the three control methods of dissolved oxygen concentration were tracked and controlled under the three weather conditions of sunny,rain and heavy rain in the BSM1 platform.The simulation results show that compared with PID 1.IMC controller,the control method proposed in this paper has higher control accuracy and better disturbance rejection performance.Finally,a dissolved oxygen concentration control system for sewage biochemical treatment process was developed.The hardware and software were designed.The control system adopts a two-layer structure: the upper layer is the monitoring layer,and the user monitoring interface is established by using MCGS configuration software.The functions of direct control of lower equipment,real-time monitoring and alarm of parameters,etc.;the lower computer adopts siemens S7-200 series PLC as the control core,which is used to detect data,and at the same time send the detected data to the control center for arithmetic processing,and transfer the control data to the frequency The frequency converter controls the speed of the blower to adjust the air volume of the aeration tank to control the dissolved oxygen concentration in the aeration tank.This system provides a hardware operating platform for the realization of the control method.