Modeling And Simulation Of Coordinated Control System For 350MW Supercritical Circulating Fluidized Bed Unit

The 19th National Congress of CPC proposed to promote the revolution of energy production and consumption,and build a clean,low-carbon,safe and efficient energy system.Clean and efficient thermal power also belongs to the green energy.As a clean combustion technology of coal,circulating fluidized bed boiler(CFB)has the characteristics of less investment,low operating cost,good coal adaptability,high combustion efficiency,less pollutant emission,strong load regulation ability,and wide market application.It is a technology suitable for China's resource characteristics and energy policy and will certainly be the new force of China's thermal power generation in the future.CFB-boiler combustion system is a multi-variable coupling,large delay,large inertia and non-linear control object.Compared with pulverized coal boiler,the lag time of main steam pressure and unit load on coal feeding is much longer than that of pulverized coal boiler,which results in that the control system of pulverized coal boiler needs to complete more complex control tasks than.With the development of thermal power units to large capacity and high parameters,it is of great significance to establish an accurate coordinated control system model for supercritical CFB boilers for the operation and control of circulating fluidized bed units.First,the overall model of coordinated control system for 350MW supercritical CFB unit is established through mechanism analysis.The model structure is divided into three parts:fuel side,steam-water side and turbine side.The fuel side takes pure delay link as the model of coal feeding system without pulverizer,and then accurately calculates the heat of furnace based on the burning carbon theory.The lumped parameter model of steam-water heating system is established by simplifying the steam-water side.Then the characteristics of superheater and spray cooling are analyzed.On the steam turbine side,the first order inertial link is used to approximate the steam turbine dynamic process.Fuel side and steam-water side are connected by furnace calorific value,steam-water side and steam turbine side are connected by main steam pressure,and the overall model structure is obtained.Then,the actual operation data of Huamei thermal power plant in Jiangsu are used for parameter identification and model validation.The static parameters of the model are calculated directly from the steady-state data,and the undetermined functions are fitted by the nonlinear regression function nlinifit of MATLAB.Then the model structure diagram is built on the Simulink simulation platform,and the dynamic optimization is carried out by using the particle swarm optimization algorithm.After obtaining the complete model,the accuracy of the model is verified by the field historical data,and the model step test is carried out.The results show that the model has good accuracy and can reflect the actual dynamic characteristics of the unit.Finally,the coordinated control system of 350MW supercritical CFB unit is designed based on the predictive control algorithm.In MATLAB software,the load of the unit is simulated to decrease first and then rise.Then the unit model is controlled by the control algorithm,and the perfect control effect is obtained.The simulation of the unit's rapid load change is carried out,and the results show that the algorithm can still maintain good control performance.