Research On Control Strategy Of Subway Environmental Control System

The urban traffic is getting more and more crowded with the rapid increasing of the urban population owing to its expanding scale of the city.Subway has become a better way out for people gradually because of its many advantages,such as punctuality,large capacity,safety and so on.Subway environmental control system takes an important role in the subway control system,which could help to create safe and comfortable environment.However,with the variable flow of visitors and vehicles,devices of subway environmental control system could only operate on one mode,which would waste the system sources and influence the ventilation effect of air conditioner.Therefore,designing a reasonable,stable and effective control strategy will be an important work.Firstly,dissertation analyzes the characteristics,components and functions of the system according to ventilation system of the air conditioner.Secondly,a master-slave control system based on PROFIBUS-DP has been designed according to the function of devices and control strategy in subway environmental control system,which has achieved the goal to control the system devices with master station S7-300PLC,slave station S7-200PLC and motor protector of slave station.Finally,the monitoring interface has been constructed to realize the visible control.According to the analysis of frequency control in environmental control system,frequency control has been implemented on large system air conditioner using frequency converter,which achieve to control large system with variable air rate and adjust the temperature at the same time.The large system mainly undertakes the temperature adjustment function in subway platform,owing to the disturbance of variable vehicle flow and visitor flow,the system temperature is hysteretic,complicated quality and random.Through analysis on mainstream control strategy,PID control system,PID control system with Smith Predictor,fuzzy control system and fuzzy PID control system have been established based on MATLAB Simulink for close-loop temperature-controlling system.According to the simulation results,fuzzy PID control strategy shows good dynamic and static performance in variable air flow and temperature control system,which shows high application value in environmental control system.