Study On Energy-saving Control Of Metro Ventilation System Based On Crowd Density Estimation

In recent years,the scale of the city has been continuously expanded.With its advantages of convenience,speed and punctuality,the subway has gradually become an indispensable choice for people to travel.The metro station has strong airtightness,large traffic volume and high ventilation requirements,which makes the energy consumption of the ventilation system account for a large proportion of the total energy consumption of rail transit,accounting for 30% of the total energy consumption of rail transit.Therefore,choosing the appropriate control method to make the subway ventilation system as energy-efficient as possible on the basis of meeting the ventilation requirements has become an urgent problem to be solved.By investigating the current situation of the ventilation system and analyzing the environmental load,passenger flow trend and passenger demand of the metro station,an energy-saving control method for the subway ventilation system based on the population density estimation was proposed.Methods Computer vision technology was used to estimate the flow density of subway stations in real time,determine the fresh air demand of metro stations,and dynamically adjust the opening of fresh air valves to save energy in ventilation system.The main research contents are as follows:(1)Research on population density estimation algorithm.Based on the theory of pixel statistics and texture analysis,this paper analyzes the environmental characteristics and passenger flow characteristics of metro stations,uses linear regression method to classify foreground pixel features for rarefaction population images,and uses support vector machine(SVM)classifier to classify local binary mode(LBP)features and gray level co-occurrence matrix(GLCM)feature for dense population images,thus achieving metro station populationdensity classification.(2)Research on control strategy of ventilation system.Aiming at the current problem of poor air quality and constant air volume control in metro stations,a new fresh air control strategy based on population density estimation is proposed.The strategy takes the fresh air demand of the personnel and the fresh air demand of the diluted building as the factors determining the fresh air demand of the station.The PID control is used to adjust the opening of the fresh air valve in real time to realize the new air volume control.(3)Control system modeling and simulation.The Simulink tool is used to establish a mathematical model for the control system.The simulation results show that the system model can dynamically adjust the opening of the fresh air valve according to the population density,control the fresh air input of the station,calculate the fresh air load of the control system within one day,and compare it with the traditional method.It shows that the method can reduce the fresh air load of 42.35% of the ventilation system,thus verifying that the method can not only improve the environmental comfort of the subway station,but also effectively reduce the energy consumption of the subway ventilation system.