Design Of Boiler Control System Based On Simatic PCS7

Boiler is the heat source and power source for industrial processes such as power generation,metallurgy,and mechanical casting.With the advancement of science and technology and the continuous improvement of computer skills,modern industry has gradually developed toward continuous,large-scale,complicated and highly automated,and the control requirements for boilers are also increasing.The controlled process mechanism of the boiler system is complex,and the characteristics of large inertia,large time delay and time-varying uncertainty are becoming more and more prominent.Moreover,under the influence of disturbance factors such as noise and load changes,the parameters of the process object and even the structure of the model will be changed,which lead to poor control effect of the PID single-loop control strategy wildly used in boiler control systems,and make it difficult to meet the requirements of real-time control and cannot solve the control problem of complex industrial processes.Therefore,a reasonable boiler control program must be designed,and the advanced process control law should be studied.Intelligent control is one of the effective control strategies.First,the basic components and working process of typical steam boiler system are introduced,and the control tasks and process parameters requirements of the boiler system are defined.On the basis of analyzing the characteristics of the boiler process object,in order to meet the control demand,ensure the safe operation of the boiler production and follow certain design principles,the comprehensive control scheme of the boiler system is designed,including the continuous control scheme and the sequence control scheme of car-opening and stopping.Secondly,aiming at the complex characteristics of boiler object,the control algorithm is studied.Based on the fuzzy control theory,the conventional PID control technology is improved,and a fuzzy PID controller is designed.The simulation model of steam pressure cascade control loop based on the radiant energy signal is established,and the simulation experiment is completed on MATLAB/Simulink.The simulation results show the superiority of the fuzzy PID control algorithm.Then,whether the PID controller or the fuzzy PID controller,their parameter settings are subjective,and the tuning process is blind,tedious,time-consuming and labor-consuming,often making the designed controller unable to be in the best working state.Therefore,on the basis of introducing the basic principle of particle swarm optimization,a particle swarm optimization method with nonlinear decreasing inertia weight is present in this paper,which combines intelligent optimization algorithm with intelligent PID control algorithm to optimize the parameters of fuzzy PID controller,so that the performance of the controller can be approximately optimal.The simulation results show that the fuzzy PID controller based on particle swarm optimization has better control effect,good robustness and strong self-adaptability.Finally,based on the boiler system unit of Siemens PCS7 process control system and SMPT-1000 process control experiment platform,the hardware and software design of the boiler control system was completed,and the integrated control scheme of the boiler system was realized with the CFC,SFC and SCL editors.The master computer uses WinCC to design the human-computer interaction interface,and completes the monitoring of the operating status of the boiler.The industrial Ethernet and fieldbus technology ensure the high speed and stability of the data interaction of the control layers of the system.The experimental results show that the system has good control effect and the automatic control of the boiler production process is realized.The structure is reasonable,the operation is stable,and the desired control requirements are achieved.