Research On PID Stabilization And Parameters Tunning Of Time Delay Systems

The stability of closed-loop system is a prerequisite for its operational value,including the adjustment of the design and control parameters of the control structure to achieve and improve control performance.PID controller is widely used in various industrial control sites due to its simple structure,clear principle and strong robustness.However,for the controlled objects with large time lag and time-varying unsteady in the industrial field,the simple PID algorithm is difficult to cope with this series of changes,not only can not achieve good control indicators,and even can not guarantee the stability.How to improve the control effect of PID basic controllers on controlled objects with significant time-delay links has both the theoretical significance and the extensive field application background.Based on the basic structure of PID controller,this research is carried out in two directions:stabilization planning and parameter tuning optimization.The main research contents and results are as follows:Firstly,the step identification method is used to identify the model of the time-delay object,and the parameter space graphical method is used to solve the PID parameter stability domain of the time-delay object.The PID parameter stability domain of the system with no time-delay and time-delay is solved respectively.The simulation is carried out in MATLAB,and the PID stability domain verification of the first-order time-delay system is carried out on the integrated test box.The results show that the parameter space graphical method is accurate and effective for solving the PID parameter stability domain of time-delay systems,and the theory and engineering are consistent.Secondly,PID parameter tuning is performed based on the identified model.Including classic PID tuning,internal model PID tuning,model mismatch and anti-step disturbance performance of internal model PID,and compare the control effect of PID and internal model PID on time-delay system.Compared with PID,internal model PID has better control effect on time-delay objects,and is more stable and robust.Finally,based on the time-varying unsteady condition of the model parameters,fuzzy control is introduced to optimize the filter parameters of the internal model PID.When the system is running,the controller corrects the filter parameters of the internal model PID in real time according to the deviation e and the deviation change rate ec.The results show that compared with the pre-optimization,the dynamic performance of the fuzzy internal model PID and the comprehensive error index ITAE are better,and the stability and robustness are improved.Theoretical research and practical results have proved that fuzzy internal model PID control can not only ensure the stability of its closed-loop system,but also has good control effect for such objects with significant time-delay links.This algorithm can provide positive guidance and reference for the control of such industrial sites,and has important significance for improving production efficiency and product quality.