Research On Robust Control Based On Dissolved Oxygen Parameters

As sewage discharge quota becomes increasingly stringent,while ensuring that the quality of effluent water meets the prescribed discharge standards,it must also consider creating as many benefits as possible.Sewage treatment plants are facing severe challenges.Among them,the accurate control of dissolved oxygen(DO)concentration is a prerequisite for obtaining better treatment effects and economic benefits.After summarizing the development and current status of sewage treatment process modeling and control technology,the robust control method of dissolved oxygen tracking in sewage treatment system is studied.The main works and innovation points are as follows:(1)The relationships among the components,reaction process,stoichiometric coefficient and kinetic parameters of activated sludge model 1(ASM1)and the structure characteristics of the benchmark simulation model(BSM1)simulation model were studied and analyzed.Including the biochemical tank reaction characteristics and secondary sedimentation characteristics.and the BSM1 benchmark simulation model is built by the MATLAB.(2)On the basis of ASM1 mechanism model and with reasonable constraints and assumptions,a simple DO-related dissolved oxygen prediction model for sewage treatment is established.Radial Basis Function Neural Network(RBFNN)is used to identify the parameters in the model.Considering that the parameters of the model have certain boundary,the output layer of RBFNN is improved.Finally,the identified parameters and the output curve of the model are obtained,verifying the effectiveness of the improved RBFNN identification system.(3)Considering the uncertainty of parameters in the sewage treatment model,the fuzzy control method is adopted to treat it,and the nonlinear dissolved oxygen model is transformed into a linear model with variable parameters,which provides a basis for the design of the subsequent controller.(4)The multi-objective H_?performance control of the model controller is transformed into the single-objective H_?performance control.The controller and the model share the fuzzy set,and LMI conditions are given to solve the existence of the controller through the LMI toolbox in MATLAB.Finally,by comparing with the conventional PID control method,it verifies the tracking and anti-interference performance of the fuzzy shared full-order dynamic output feedback controller to the dissolved oxygen setting value.