The Research Of Fuzzy Decoupling Control Based On S7-300PLC On Water Tank Level Control

With the industrial development, the liquid level control is more and more widelyapplied. Three-tank water tank level control has large time delay, bad robustness andnonlinear. The mathematical models obtained by transfer function are not accurate, theconventional control methods are difficult to acquire satisfactory results, and the upperwater tank exists strong coupling to the lower water tank in the liquid level control circuit.In order to solve these problems, this paper makes the liquid level of the upper water tankand lower water tank as research object. On the analysis of the liquid level features and thecoupled characteristics, level fuzzy decoupling control scheme is put forward. It wassimulated and tested. The results show that the fuzzy decoupling control plan is possible,and has better control effect than the conventional control and conventional decouplingcontrol.In the environment of MATLAB software, the transfer function of two object channelsand an associated channel were established by the step response method, and decouplingcoefficient was used in coupling of the upper water tank and the lower water tank, and thefuzzy decoupling control model was established. The related parameters were adjusted toget optimal curve, and it was compared with conventional PID control and theconventional decoupling control in the way of setpoint disturbance and processdisturbance.The fuzzy decoupling control experiment was achieved in AE2000A experiment devicewhich was produced by Zhejiang SUPCON, Inc. The control algorithm was applied onSiemens S7-300PLC, and it was programmed through the LAD and STL, and it wascompleted in the WINCC monitoring system by the variable connection, image editingand report forms, etc. Fuzzy decoupling control experiment was achieved.The level control curve of test results show that both in the MATLAB environment andin the S7-300PLC experimental condition, the fuzzy decoupling control effect is muchsuperier than the conventional decoupling control with shorter adjusting time, highercontrol precision and almost no overshoot, shorter reaction times, and anti-vibrationdisturbance capability. In conclusion, it has better control performance.