The Research On Time-Delay Multivariable Internal Model Control Algorithms

With the rapid development of industrialization, industrial processes become more complex.The conventional PID control has been difficult to adapt to the modern control requirements.For the advantages of simple design, good control performance,excellent robustness, as well as good prediction ability, the internal model control(IMC) shows the strong vitality to solve the control problems of the multivariable systems.This paper mainly studies internal model control designed for the multivariable time-delay system in order to find simple,effective and practical method.Firstly, the IMC strategy for single variable systems was introduced. Based on the first-order Pade approximation and the all-pole approximation,internal model controls are designed for one-order time-delay system and second-order time-delay system.Then,the realization of IMC-PID control is introduced.Secondly, in order to effectively solve the common phenomenon of saturation in the industrial field,this paper proposes the anti-windup control method based on a combination of Bessel filter optimal state feedback and modified internal model control.Simulation studies show that:the method has a strong anti-disturbance ability and robust performance. This method is also available for valve position limit setting in the industrial field.In addition,correlation analysis of a system and the ways to reduce and eliminate coupled problems are introduced for multi-variable system.Then,four kinds of decoupling control design methods are introduced.At last, a decoupling dual internal model controller matrix design method is proposed for multi-variable time-delay input-output system in industrial processes.By using NLJ algorithm to simplify the order of analytical model, the calculated amount for deduce the matrix of decoupler is reduced. The method uses dual-internal mode structure to compensate the control quality decline which the process model uncertainty causes. Simulation results show this method has stronger robustness and anti-coupling capability.In order to meet the practical requirements of DCS in industrial field,internal model controller should be transformed into PID controller, the system can still be near or completely decoupled, and the desired results is achieve.