Research On PH Control Of Sewage By Fuzzy Gain Scheduling Internal Model PID

Faced with the domestic present situation of water shortage and serious water pollution,effective measures should be taken to deal with wastewater which has become a urgent problem.Sewage treatment involves multiple complex control processes.Among them,PH neutralization reaction is a very crucial process.PH has a significant influence on other effluent indicators,and its stable control will directly affect whether the whole process of sewage treatment is up to standard.For this reason,in this thesis,a fuzzy gain scheduling internal model PID control strategy applied in the PH neutralization process is proposed.The whole technical process of sewage treatment is researched and the key process structures and functions are analyzed in detail.The mechanism of PH acid-base neutralization reaction process is analyzed which plays an important role in the process of sewage treatment.According to the ionic equilibrium and the law of mass conservation,the approximate mathematical model of PH neutralization reaction is established.The basic characteristics of neutralization process is represented and the factors that affect the stability of PH value control are analyzed.Considering the neutralization reaction in the sewage treatment site,PH control has the characteristics of strong nonlinearity,big lag,uncertainty and poor robustness.Single closed loop PID control is often used for the control of PH,but it has certain deficiency.In this thesis,the internal model control strategy applied in sewage PH neutralization process is presented.The internal model PID controller is built up to ensure the stability of PH.In order to verify the feasibility of the designed controller,the simulation experiment is proceeded by using software and the comparison with the other conventional control methods from several aspects of performance is accomplished.The internal model PID control can obviously improve the target tracking characteristics of the controlled object and improve the ability of anti-interference.Meanwhile,the dynamic characteristic of the system can be satisfied better.Even if the model mismatches,it can also achieve good control effect.And it can reduce the number of parameter adjustment,the design structure is also simple.The disadvantage is that the randomness of the setting parameters still exists and the adaptive ability of the controller is not good enough when the parameters need to be changed under abnormal conditions.In view of the deficiency existing in the internal model PID parameter adjustment process,To further optimize the controller,in this thesis,a fuzzy gain scheduling internal model PID control strategy is put forward which can adjust the parameters online.The two-dimension fuzzy controller is designed and the error and error variety-rate of control system are treated as the input.The online adjustment of the internal model PID parameter is accomplished by fuzzy output.The optimized controller is applied to the PH adjustment,the simulation experiment is carried out by utilizing software.The results show that the proposed control method can improve the performance of the control system,adjust the real-time parameters online and enhance the adaptability.