Research On The Application Of Sampling And Positioning Control Strategy For Carbon Content In Boiler Fly Ash

Boiler fly ash carbon content is an important technical indicator of coal-fired boilers in thermal power plants and other plants,which is related to the economic efficiency of boiler operation.The core of the automatic boiler fly ash content detection device is the sampling and positioning controller.Since the boiler is a continuous production device and the operating environment is characterized by high temperature,vibration and high dust,the accuracy and reliability of the sampling and positioning controller are highly required.To address this subject background,an accurate physical model is established for the DC gear motor,the power source of the device,and the rotary mechanism for automatic detection of fly ash content in boilers,and a control strategy is explored to control the positioning accuracy based on this research object.In this thesis,the following work is done for the application research of the control strategy of fly ash carbon content sampling.First,according to the rotating structure of the boiler fly ash automatic detection device and the characteristics of the DC gear motor,the simulation software Matlab/Simscape is used to establish an accurate physical model.The model includes motor drive model,DC brushed motor body model,planetary gearbox model,and load model.The accurate simulation modeling of the servo motor and its load is helpful to verify the control effect of the control strategy for the actual controlled object,which is more suitable for the actual situation.Second,a sliding mode reverse step control algorithm is designed for the carbon content sampling and positioning control system of boiler fly ash.The sliding mode convergence law is improved to achieve the effect of reducing the system jitter,and the stability of the control system is proved according to the Lyapunov function.Finally,the control strategy of this thesis is compared with ordinary PID,fuzzy PID and ordinary sliding mode control algorithms under different mass loads for simulation.The simulation results show that the sliding mode backstepping control strategy is accurate in servo control of DC geared motor with load model position under different mass loads without overshoot oscillation,and the control effect is superior compared with several other control strategies.Third,the hardware and software design of the system slave motor controller.The hardware circuit design uses the STM32F373CCT6 microcontroller as the main controller,and the rest of the parts include the isolated power supply circuit,encoder shaping circuit,optocoupler isolation circuit,driver circuit,isolated RS485 communication circuit,and current acquisition circuit.The software part includes the calculation of motor running speed and displacement by rotary encoder input signal,overcurrent protection program,communication protocol and control algorithm.Finally,the main functions of the motor controller are tested by establishing communication with the upper computer software through MODBUS communication protocol as a slave.The experimental results show that the position servo of the boiler fly ash sampling and positioning control system with the sliding mode backstepping control strategy as the core can realize the positioning function more accurately and with strong robustness.