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Research On Internal Model Control And Disturbance Rejection Of Industrial Systems

Posted on:2020-07-17Degree:MasterType:Thesis
Country:ChinaCandidate:H YinFull Text:PDF
GTID:2428330623963598Subject:Control Engineering
Abstract/Summary:PDF Full Text Request
In the process control of modern industrial processes,the reference tracking performance and the disturbance rejection ability have become a central topic in control theory.However,we realize that once we focus more on the reference tracking performance,the disturbance rejection ability will inevitably be affected.Therefore,how to balance the relationship between the two has always been a theoretical problem in the field of control,but also an urgent problem to be solved in the industrial field.In view of the widespread phenomenon in industrial process,this paper discusses the design of controller structure which can simultaneously guarantee the two performance of the system from the perspective of theoretical research and practical application deeply.The main achievements and contributions are summarized as follows:1?Integrating and unstable processes with time delay are commonly encountered in process industries,e.g.,temperature maintenance of various industrial reactors and level regulation of biochemical liquid tanks.For this kind of system,this paper presents a PID controller based on internal model control to improve the disturbance rejection ability of the system.Firstly,the internal model controller is designed by H2optimal control method,and then the PID parameters are obtained by MaCulurin series approximation method.In order to balance the tracking performance and disturbance rejection ability of the system,a set point filter is introduced to reduce excessive overshoot in the set-point response.At the same time,a number of simulation examples are introduced to certify the effectiveness of the proposed control strategy.2?The traditional Smith predictor is not able to eliminate the constant load disturbance for the system model that has an integral part.In this paper,the structure of Smith predictor is modified so that the set point tracking response and the input disturbance response can be successfully decoupled via the proposed approach to reduce controller design difficulties by tuning two parameters.Also,steady state error caused by the load disturbance in the integral process can be eliminated,so that the system can improve the two abilities of the system at the same time.The method proposed in this paper is applied in dryer section of paper-making process.The simulation results show that the modified Smith predictor structure proposed in this paper has a good control effect.3?In order to improve the reference tracking performance and disturbance rejection ability for multi-input/multi-output?MIMO?systems,a decoupling multivariable control strategy is proposed.The strategy includes a multivariable disturbance observer?MDOB?and a decoupling controller.This MDOB is introduced to improve the system performances when the system encounters severe external disturbances.H2optimal scheme is utilized to design the MDOB filter.The controller is developed based on an inverse control method to improve the reference tracking performance of the system.The control strategy greatly simplifies the design process of disturbance observer and the decoupling controller.Simulation results certify the effectiveness of the proposed control strategy.
Keywords/Search Tags:disturbance rejection control, internal model control, H2 optimal control, disturbance observer
PDF Full Text Request
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