Research On Fuzzy Control In Circulating Fluidized Bed Boiler System

In recent years,with the continuous development of industrialization,the status of coal resources in China’s industrial production has become more important.The most typical distribution feature of coal resources in China is the lack of high-quality coal reserves,but the proportion of inferior coalreserves is relatively high.Circulating fluidized bed boiler is an efficient combustion boiler that specifically utilizes low-quality coal combustion,which can solve various problems caused by low-quality coal combustion and has the advantages of energy conservation and emission reduction.However,the complex structure of the circulating fluidized bed boiler itself makes it difficult to control,and as it is a new type of boiler,the control technology for the circulating fluidized bed boiler is not yet mature.Therefore,studying advanced control strategies suitable for circulating fluidized bed boiler systems and implementing them in the system is of great significance for the development of control technology in circulating fluidized bed boiler systems.To solve the control problem of the circulating fluidized bed boiler system,this project conducts a specific analysis of the circulating fluidized bed boiler system,deeply analyzes and understands the dynamic characteristics of the bed temperature and main steam pressure controlled objects in the combustion system,and establishes a model structure of the circulating fluidized bed boiler bed temperature and main steam pressure object;Through the step response experiment,the operating data of bed temperature and main steam pressure in the circulating fluidized bed boiler system are obtained,and the parameter identification is carried out using the drawing method and the two-point method,and the approximate mathematical model of bed temperature and main steam pressure is obtained.The combustion system of a circulating fluidized bed boiler is a multi input multi output system,and the bed temperature and main steam pressure are also affected by the combined interference of coal supply and primary air flow,respectively.In this paper,the relative gain method is used to analyze the coupling between the bed temperature and the main steam pressure.It is found that there is a strong coupling between the bed temperature and the main steam pressure system.Therefore,this article selects the feedforward decoupling method and designs a feedforward decoupling controller for decoupling control simulation of the bed temperature and main steam pressure system.The simulation results show that the decoupling effect is good.The combustion system of a circulating fluidized bed boiler is a complex control system,which not only has simple coupling characteristics,but also has problems such as nonlinearity and hysteresis.This indicates that a simple decoupling controller cannot meet the requirements of complex combustion system control circuits.The fuzzy PID controller has certain advantages in solving such complex problems,reducing the requirement for establishing accurate mathematical models in complex control systems,and meeting the control requirements of combustion systems.This project adopts the method of applying fuzzy PID controller on the basis of decoupling control loop.For the coal feed control bed temperature loop and the primary air flow control main steam pressure loop,conventional PID controller and fuzzy PID controller are respectively used for MATLAB simulation comparison.The results show that this method can not only eliminate the coupling effect in the combustion system,but also effectively solve the nonlinearity and hysteresis of the combustion system,and improve the overall anti-interference ability of the system.In order to achieve advanced control and real-time monitoring of the combustion system of a circulating fluidized bed boiler,this article adopts the JX-300 XP control system of Zhejiang Central Control for hardware design and software configuration.A list of measuring points has been organized and hardware selection has been carried out on the hardware.Control circuit configuration,fuzzy PID control algorithm design,and configuration development of upper computer monitoring screens have been completed on the software.However,due to the epidemic,the site is in a parked state,so it is temporarily impossible to verify the actual feasibility of the boiler fuzzy control system.