Design And Development Of The Teaching Experiment Platform For The Air Heating And Mixing Process Control System With Non-minimum Phase Characteristics

Non-minimum phase systems with inverse characteristics bring particular difficulties to conventional error-based PID controller designs.Moreover,the description of non-minimum phase concept in the teaching of automation is more emphasis on mathematical theory.Therefore,the non-minimum phase system and its control problems have been one of the most difficult and important points in automated teaching.With the support of the project of Liaoning Province Metallurgical Comprehensive Automation Engineering Laboratory,the paper takes the air heating and mixing process as the physical object,and designs and develops a teaching experiment platform of air heating and mixing process with non-minimum phase characteristics which is highly consistent with industrial environment.By reasonably constructing experimental conditions,a physically controlled object device with non-minimum phase characteristics is constructed.Based on this platform,some experiments on identification and control of non-minimum phase industrial process can be carried out in industrial environment,which helps to deepen the understanding of non-minimum phase concept among automation major students and improve the teaching effect.The specific work of this paper is as follows:(1)The development of the existing process control experiment teaching platform and the control of non-minimum phase system are reviewed in detail.And taking the process of air heating and mixing as the controlled object,this article analyzed the teaching experiment requirements of the process control experimental system platform with non-minimum phase characteristics with the aim of assisting the teaching experiment.(2)Based on the principle of conservation of mass and conservation of energy,a mathematical model is established for the air-heating mixing process.Based on the reasonable construction of experimental conditions,the hot air flow rate is taken as input and the mixed temperature is taken as output to construct the controlled object.Simulation results show that the controlled object has obvious reverse characteristics,indicating the feasibility of the developed experimental device in principle.(3)The designed air heating and mixing process control teaching experimental platform system architecture is composed of controlled objects,instrumentation and actuators,PLC control system,monitoring computer and model computer in the air heating and mixing process.In this system,the design of teaching experiment related functional modules can be carried out for routine operation,recursive identification,pole configuration controller design,pole configuration controller operation and other teaching experiments.(4)Based on Siemens S7-300 PLC control system and MATLAB,this paper developed a non-minimum phase process control teaching experiment platform software.PLC process control and monitoring software was developed using Siemens industrial control software.The model computer software with complicated calculation tasks(recursion identification and controller design)was developed by MATLAB,and the data communication between PLC system and model machine software was realized by OPC.(5)In this teaching experiment platform,this article is verified experimentally Step response experiments show that the controlled object has obvious reverse characteristics.Recursion recognition experiment can identify the controlled object model,which has unstable zero point.Polarization control experiments show that the pole configuration controller can achieve closed-loop system stability and controlled variables to eliminate steady-state tracking error.The platform has a highly simulated industrial scene environment,intuitive and easy to understand,safe,reliable,convenient and flexible advantages,and it will play a certain effect in promoting the reform of automated teaching.