Simulation And Experimental Research On Active Disturbance Rejection Control Of Three-Tank Liquid Level

The three-tank liquid level control system is a physical simulation object of industrial process control system,which has the characteristics of nonlinearity,hysteresis,uncertainty and so on.It can be effectively used to simulate most process control systems in modern industry.Active disturbance rejection control technology is an improvement on PID control algorithm,which is not limited to the limitations of "the absolute invariance principle" and"the internal model principle".It has the advantages of not relying on the mathematical model of the controlled object,and being simple and easy to implement.This paper focuses on the simulation and experimental research of the three-tank liquid level control based on active disturbance rejection control.Firstly,the mathematical model of the three-tank system is established according to the mechanism modeling method.And the three-tank system in the laboratory is taken as the object,the parameters of the mathematical model of the system are measured by the experimental method,and the step response simulation experiment is carried out to verify the correctness of the model.Then,based on the active disturbance rejection control,the simulation and experimental research of the basic active disturbance rejection control of the water tank level are carried out.Aiming at the problems of the secondary disturbance,the over dependence of the control performance on the parameter setting,and the majority of the parameters derived from the experience adjustment,the corresponding improved algorithm is proposed,then the simulation and experimental research are carried out.(1)In order to solve the problem of secondary disturbance in the double-tank system,an active disturbance rejection cascade control algorithm is proposed.By using this improved algorithm,the problem that the liquid level in the middle water tank cannot overcome the disturbance in the secondary circuit when it is disturbed violently and frequently is solved,and the dynamic characteristics of the system and the control quality of the system are improved.(2)In view of the problem that the parameters of the active disturbance rejection control algorithm are too many to be adjusted and the dynamic performance of the system is considered,an active disturbance rejection cascade control algorithm based on the characteristics of phase trajectory is proposed.With this algorithm,the expected motion direction of the phase variable is calculated according to the actual position of the phase variable in the phase plane and the preset phase trajectory,so that the phase variable of the control system can be forced to move along the preset phase trajectory.The adjustment of the performance of the control system,the parameters of active disturbance rejection control are reduced,and the dynamic process trajectory planning of the system response is realized.The influence of phase trajectory inclination on control performance is also analyzed in detail.(3)In view of the problem that the parameters of active disturbance rejection control with phase trajectory characteristics are mainly depend on manual adjustment,an active disturbance rejection cascade control algorithm with phase trajectory characteristics based on social spider group optimization is proposed to realize the adaptive adjustment of parameters of active disturbance rejection control.The effectiveness of the algorithm is verified through simulation and experiment.Finally,the above-mentioned active disturbance rejection control algorithm and its improved algorithm are applied to the experimental device of three-tank water for liquid level control experimental research.The results show that the improved active disturbance rejection control algorithm have many advantages of not relying on the mathematical model,such as the controlled object,less dependence of the controller parameters on the artificial experience,simple structure,easy implementation,good tracking performance,strong anti-interference ability and is easy to be practical engineering applications.