Research On Three-tank Liquid Level Control Algorithm Based On Multi-model IMC-PID

Liquid level is a common process parameter in petrochemical,metallurgical,food filling and sewage treatment industries.With the continuous development of society,the industrial production process is becoming more and more complex.If the traditional PID control algorithm is still used to control it,the control effect will often be unsatisfactory.Therefore,developing more advanced control strategies to achieve stable,fast and accurate control of industrial processes is of great significance for ensuring the process indicators of industrial production and achieving higher economic benefits.As a liquid level process system with nonlinearity,large inertia and time delay,three-tank system is very suitable for simulating many industrial processes with complex characteristics.In this thesis,three-tank system is taken as the research object,and the multi-model IMC-PID control algorithm is adopted to realize the stable,fast and accurate control of its liquid level.The main research contents of this thesis are as follows:(1)System modeling.According to the non-linear characteristic of three-tank system,the multi-model method is used to analyze and model three-tank system.The model structure is deduced by mechanism method.,and the parameters of the model are estimated by least squares algorithm and particle swarm optimization algorithm respectively.Finally,a more accurate mathematical model is determined by model checking.(2)Control algorithm research.According to the principle of PID control algorithm and internal model control algorithm,the traditional PID controller and IMC-PID controller are designed.The control effect of the two controllers is simulated and compared in MATLAB software,and the results show that the control effect of IMC-PID controller is better.(3)Control system design.According to the composition and characteristics of process control system,and combining the mathematical model of three-tank system and the control algorithm studied,a multi-model IMC-PID control system is designed,in which the model controller is switched according to the given liquid level height.The simulation results of this control system and the traditional PID control system are compared in MATLAB software,and the results show that the multi-model IMC-PID control system's control performance is better.(4)On-site debugging and control results analysis.Combining with the field THJ-3 three-tank system experimental equipment,the multi-model IMC-PID control system designed in this thesis is debugged.After debugging,the actual control effect of this control system and the traditional PID control system is compared,and the results show that the multi-model IMC-PID control system is superior to the traditional PID control system in many system performance indexes such as maximum dynamic deviation,overshoot,adjustment time,anti-interference and stability,and has practical application value.