Researches On Control System For Municipal Wastewater Treatment

With the development of wastewater treatment technics, the demand of automatization level in wastewater treatment is more and more complex. At last years, the theory, technics research and application of environment protect in our country comes up to foreign, but the equipment and automatic control system has considerable gap.In this thesis, the distributed control system(DCS) for wastewater treatment was designed with research of municipal wastewater treatment technics. The control system consists of industrial person computer(IPC), PLC control system and local intelligent control instruments, etc The DCS system implements distributed control and centralized supervision in wastewater treatment.The industrial computer mainly implements the functions of long-range supervision and management it includes: dynamic show of technics flow, real time data acquirement and show, history data save and print, fault alarm, etc; The PLC control system mainly accomplishes the wastewater technics flow control, harmonizes the logical relationship among local intelligent control instruments and transmits the state of each local equipment to the industrial computer, simultaneously, the PLC control station receives the control commands from the industrial computer; The local intelligent units take charge of the correlated parameters' measure> disposal and control, and it will transmit the related parameters to the computer, etc.In this thesis, introduced municipal wastewater treatment technics, the integrated application program development of computer, the design method of PLC control station, the communication between PLC control system and computer, and the network of wastewater treatment with industrial Ethernet was also discussed.The dissolved oxygen (DO) is one of the most crucial parameter in municipal wastewater treatment system. DO is choosed as the control object and DO control system from theory research. Because of the complexity, lag, process disturbances, dynamic, nonlinear, difficult tofound exact model in the DO biochemistry process, the performance of traditional control strategies is beyond human's satisfaction. Author brings forward control strategy of artificial intelligent with predictive model and proposes to improve on the control system of wastewater treatmentAt last, it simulates the design model with simulink in MATLAB and gives the simulation results and analyses. The experiments are made to show the effectiveness and robustness of the proposed method.