Development Of Control System For Cement Grinding Based On Multi-objective Optimization And Fractional-order

Cement plays a very important role in national development and is the basic materials of construction industry.Cement combined grinding is an important link in cement production,which determines the quality and quality of cement.Due to the advantages of series structure of roller press and ball mill,cement combined grinding can improve the quality and efficiency of cement production.However,there are still some problems such as the need to manually set the target value,low practicability and low control accuracy,so that the multi-objective autonomous control cannot be realized,which leads to the current situation of large consumption of manpower and material resources and low energy efficiency.This makes it difficult for the traditional control method to ensure the optimal control parameters such as particle size distribution,mill load and flow into the mill.Therefore,this paper presents an independent optimization control system suitable for cement grinding in our country,to achieve the improvement of the pulverization efficiency,cement quality stability,it based on the combined cement grinding technology,combined with multi-objective optimization,neural network and other methods advantages,the contents are as follows:I.In order to achieve the optimal control goal of cement combined grinding energy consumption ratio,a multi-objective optimization algorithm of NSGA-II based on BP neural network was proposed.BP neural network was used to give the dynamic relationship model between stable flow bin weight,mill bucket current,cement particle size distribution and feeding amount,main circulation fan speed and separator speed.NSGA-II multi-objective optimization method was used to give the comprehensive evaluation target values of stable flow warehouse weight,mill bucket current and cement particle size distribution.On the basis of the comprehensive evaluation of the target value,in order to facilitate the engineering implementation,the target separation technology is used to realize the target tracking value of the three control loop such as the steady flow bin.Ⅱ.According to the process characteristics of each control loop of cement combined grinding,using fractional order and sliding mode control technology,three controller design methods such as steady flow bin are proposed.1)Aiming at the pre-grinding closed-loop loop composed of roll press and weighing bin,based on the field data,the dynamic model between feed volume and steady flow bin weight was established by using the data fitting method,and the integral separation PID steady flow bin controller design procedure was given to ensure the stability of steady flow bin;2)Aiming at the closed loop circuit of final grinding consisting of ball mill and separator,the fractional order dynamic relationship model between the current and circulating fan of ball mill was established by using the fractional order theory and particle swarm optimization algorithm,and the fractional order integral sliding mode controller was designed to realize the stable load of ball mill.3)For cement quality control,on the basis of optimizing the particle size distribution content of cement in the optimization layer,a fractional PID controller based on the fractional order model is designed for stable control of the particle size distribution content of cement.Finally,the optimal control setting value of the optimized control layer is used to optimize the overall closed-loop control of the final grinding loop.III.Compiled the cement combined grinding control optimization software which integrates NSGA-II optimization objective algorithm and controller.1)OPC communication was used to realize the data interaction between the optimized control software and DCS control system of cement combined grinding,and SQL Server was used to realize the data storage.2)Based on the real-time cement grinding data collected from the database,the optimal setting value optimization module of the control loop of the cement combined grinding system is designed.3)Design the overall structure and function of the controller of cement combined grinding system.4)Engineering verification of the control effect of its control software.