| The controller performance assessment is an important and necessary measure to realize the health maintenance of the whole life cycle of the system.It aims to solve the problem that the performance of the control loop deteriorates and even security risks occur due to the time-varying system.However,there is still a lack of scientific and reasonable controller performance assessment methods and techniques for the common MPC-PID two-layer complex control system in the actual industry.Therefore,in this thesis,the styrene ratio MPC-PID subsystem in a styrene hydrocarbonization unit of an enterprise is taken as the research object.Starting from the process mechanism analysis,exploratory research is carried out around the system modeling,PID and dual-layer MPCPID architecture controller performance assessment methods,and application software development.The main work is as follows:1)Process mechanism analysis and simulation modeling of benzene ratio control systemBased on the in-depth analysis of the production process mechanism of benzene ratio,combined with the actual control strategy of the system,the architecture of benzene ratio multi-loop ratio control system with one master and four pairs was constructed under the traditional PID control and MPC-PID two-layer control schemes respectively.Then combined with the process parameters of the device and the operating conditions of the system,through reasonable assumptions,the mathematical model of each part of the system was established.Based on the MATLAB/Simulink simulation software,the system simulation platform of PID control and MPC-PID double-layer control of benzene ratio was built.Then,using the actual system data under normal working conditions,the usability of the simulation platform of benzene ratio system is verified,which lays a foundation for the subsequent research on the performance assessment method of system controller.2)Research on controller performance assessment method of PID control architecture for benzene ratio control systemIn order to reduce the influence of non-Gaussian noise and data outliers on the performance assessment results of benzene-ene ratio control system based on PID control architecture,five single-loop controllers in the system were evaluated in real time using sliding window method based on improved GME assessment criteria.Then the system follow-up performance index is designed to evaluate the coupling performance of each loop controller.Then,based on the above two performance assessment indexes,a joint performance assessment index of the system controller was developed,and the index fusion weight was determined by Spearman correlation coefficient statistical analysis method,so as to avoid the subjectivity of expert experience to determine the weight,so as to realize the overall performance assessment of the system PID controller.Finally,the effectiveness of the proposed assessment method is verified by the aforementioned simulation system platform.3)Study on the controller performance assessment method of benzene ratio MPCPID dual architecture control systemIn order to overcome the defect of translation invariance in real-time assessment by improving the GME standard,a user defined assessment benchmark was designed for benzene ratio control system based on MPC-PID two-layer control architecture.Then,by analyzing the internal characteristics of the two-layer control structure,the relationship between materials and performance between MPC and vinyl PID loop was sorted out.Based on the user-defined assessment indexes,the performance assessment indexes of MPC-PID vinyl controller and benzene loop controller were designed respectively.Then,based on the performance indexes mentioned above and system servo,a joint performance assessment index of the system controller is developed,so as to realize the overall performance assessment of the system controller under the MPC-PID dual-layer architecture.Finally,the effectiveness of the controller performance assessment method is verified by the system simulation platform.4)Design and development of controller performance assessment software for benzene ratio control systemIn view of the application requirements for the performance assessment of benzene ratio control system,the technical scheme of the assessment system is determined by demonstration and analysis,and the software for the performance assessment of benzene ratio control system controller is designed and developed by means of the APP Designer toolbox of MATLAB and My SQL database.After testing the software on user login,user management,performance assessment of PID single-layer architecture and MPC-PID double-layer architecture controller,historical data query,event record,etc.,the functions have reached the expected goals,and the operation is convenient,easy to use and easy to maintain,which has carried out beneficial exploration for later engineering applications. |
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