Research On Improved Model Predictive Control Based On Laguerre Function And Its Applications

In recent years,with the rapid development of economy and technology,the country and the people require to improve the safety and stability of power supply.This makes the thermal process control more complicated,and it is difficult to achieve the desired control effect using conventional control methods.Therefore,we study advanced control strategies and design highperformance control system,which can meet the requirements of thermal process control.It will help to improve the automation of the thermal process and is an important part of the field of thermal control.Because the structure of PID control algorithm is intuitive and easy to understand,it has been widely used.However,modern thermal equipment and thermal processes are becoming larger and more complex,and their control requirements are constantly increasing.The conventionnal linear PID control methods is difficult to meet the control requirements.On the basis of the integer-order PID,the fractional-order PID introduces two parameters,which makes the controller more flexible and more suitable for the control requirements of various occasions.Predictive control is a new class of computer control algorithms that appeared at the end of the last century,through twenty years of research and practice has proved that it has a good track,robustness and adaptability.If we can combine the predictive control with PID control or fractional-order PID to develop a new control algorithm,and apply it to thermal control.It will help to improve the automation of thermal process.In this paper,the circulating fluidized bed boiler bed temperature system is taken as the controlled object.The structure of circulating fluidized bed boiler system and its bed temperature mathematical model are analyzed.Aiming at the requirements of control system and,a PID predictive control algorithm based on Laguerre function model is proposed,which combines the advantages of traditional PID and model predictive control.The algorithm takes a typical predictive control as the starting point,adopts the Laguerre function model which is insensitive to time delay and structural change as the prediction model.It uses the minimum recursive method with forgetting factor to identify the model parameters online.In order to further combine the predictive control with the PID control,the coefficients of PID are added to the rolling optimization target.The simulation analysis by MATLAB platform shows that the control method has excellent control quality.Then the fractional-order PID predictive control algorithm based on Laguerre function model is proposed.The algorithm transforms the performance index of rolling optimization into the structural form of fractional PID.Two parameters increase the flexibility of the controller and the result is closer to the expected control effect.Finally,it is extended to the multivariate domain.A multivariable algorithm that PID predictive control based on Laguerre function model is proposed.The load cell system of thermal power unit is taken as the controlled object.The effectiveness of the algorithm is verified by experimental simulation.