Research On IMC-PID Control Method Based On Step Identification

In the existing industrial controller,PID controller is the most widely used in industrial process control applications,especially the temperature control in this topic.Due to the unavoidable phenomenon of large lag in temperature control,it is very important to reasonably configure the parameters of PID controller and improve the control precision of the large lag system.The parameter configuration of the controller is closely related to the model,and the accurate establishment of the industrial process model is the basis of the control precision.In addition,when the control algorithm is verified by experiments,it is often difficult to get the actual controlled object,or the development site is far away from the production site,which makes the efficiency,safety and accuracy greatly reduced.In this paper,the internal model PID(IMC-PID)control algorithm and the simulated industrial object system basing on step identification are studied.The research contents include three aspects:step response identification,IMC-PID control algorithm and simulation industrial object experiment system.The main research results of this paper include:(1)The identification method basing on multiple integral time-domain robustness is studied for the first order time-delay objects,integrals plus first order delay objects and high-order time-delay industry.Based on this idea,the parameter identification of the model under the non-zero initial condition is also studied.Meanwhile,aiming at noisy occasions,an improved algorithm of multiple integral identification based on particle swarm optimization is proposed,which optimizes the starting point and terminal data selection,and improves the identification accuracy greatly.The simulation experiment and the actual system data modeling verify the effectiveness of the improved method.(2)Basing on the research of internal model control,the all pole approximation method is introduced into the approximation of delay terms for internal model PID controller,and the idea of internal model control and incremental incomplete differential PID are combined.The general formula of the parameter tuning of the internal model PID controller for the first and two order time-delay systems is derived through the McLaughlin expansion.The simulation example shows that the method proposed in this chapter is suitable for large lag system,fast tracking,and small overshoot and adaptable to model mismatch,and its robustness is good.(3)A simulation platform of semi physical composite controlled object is designed,which is the integrated control experiment box.The time delay is used to simulate the object with large delay.The object model is identified by improved multiple integral method.The system has almost no overshoot,and can track the given value very well and verify the superiority of the IMC-PID in the large lag system.(4)Basing on OPC technology,this paper builds a simulation experiment platform integrating MCGS and MATLAB.In the MATLAB,the transfer function is used to realize the virtualization of the controlled object.The industrial control device software MCGS is used as the controller to get the output of the control volume,which is closer to the actual control process.