Predictive Control Algorithm With Adjustable Factors And Its Application In Gas Fractionation Unit

With the rapid development of computer technology,the application of automatic control systems in the field of process industry control is becoming more and more extensive.Especially in the production of the petrochemical industry,due to uncertain factors such as raw materials,product specifications,and production environment,it is difficult for conventional control methods to obtain effective control.Therefore,research and development of advanced control technologies are required to improve the production efficiency of the enterprise and the economy benefit.This article firstly gives an overview of advanced control,and introduces the development of predictive control,then introduces PID control,Smith predictive control and predictive PI control algorithms and their basic principles,and analyzes the simulation results.Secondly,for conventional PID control methods applied to complex petrochemical processes such as gas fractionation unit with large lag and nonlinearity,often fail to obtain satisfactory control results,a predictive control algorithm with adjustable factors is proposed.The data obtained from the jump response establishes the transfer function model,and the control law is obtained through the prediction model,feedback correction,and rolling optimization.An adjustable factor is added to the objective function,and the prediction error compensation is improved in the process of feedback correction.The improvement effectively reduces the impact of the output error due to model mismatch on control performance.The proposed algorithm is verified based on the dynamic model obtained from the field data of a desorption tower of Jinzhou Petrochemical Company.The simulation results show that the proposed algorithm has a good control effect.Finally,the project implementation process of the advanced control of the gas fractionation unit is elaborated in detail.It mainly includes: the establishment of advanced control platform and the completion of the communication interface configuration according to the process requirements,and the real-time transmission and exchange of data between the upper computer and the lower computer DCS.On this basis,through the Zhejiang University Central Control ECS-700 series DCS,complete the undisturbed switching of advanced control and conventional control,the advanced control system assignment protection and abnormal fluctuation processing,and other interface logic design and advanced control operation interface DCS configuration,and carried out offline debugging and online simulation operation.After the advanced control is put into using,the operation of the device is more stable,automatic and stable control is achieved,product quality and yield are improved to a certain extent,and energy consumption is reduced.Overall,advanced control has brought considerable economic benefits to the enterprise.