Monlinear Modeling And Predictive Control Of A Circulating Fluidized Bed Boiler System

Circulating fluidized bed boiler(CFB)is a new clean combustion technology that has been developing rapidly in recent 30 years.Because of its wide fuel adaptability and high efficiency of desulfurization and denitration,it is in line with the two social development themes of current energy and environment.However,circulating fluidized bed boiler is a non-linear,strong coupling,multiple-input-multiple-output,and large time delay system.The technical characteristic of its fluidized combustion makes the exchange flow of materials and energy much more complicated than traditional pulverized coal boiler,which also makes the control of circulating fluidized bed boiler more difficult.Therefore,it is a very practical work to establish a dynamic mathematical model for the control of a circulating fluidized bed.Based on the above reasons,this paper first fully understand the process of circulating fluidized bed boiler and the coupling relationship between the various variables of the coordinated control system,and then establish the dynamic model of circulating fluidized bed temperature,drum water wall,superheater and steam turbine,And combined them into the circulating fluidized bed boiler coordination control system model.Finally,based on the field data of 330MW circulating fluidized bed boiler in Jinghai power plant,Inner Mongolia,the continuous step dynamic simulation and real-time simulation of the model were carried out.The real-time simulation results are consistent with the field data of CFB boiler.In order to solve the nonlinear problem of coordinated control system,the T-S fuzzy model is introduced based on the coordinated control system model built,and the load is taken as the only antecedent variable of the fuzzy model.Combining the fuzzy inference system with the predictive control algorithm,we use the T-S fuzzy model as the predictive control prediction model,and form the nonlinear fuzzy predictive controller.Finally,the designed controller is applied to CFB boiler coordination control system.The simulation results show that the proposed nonlinear fuzzy predictive controller can control the bed temperature,the main steam pressure and the power well.When the load of the unit fluctuates over a wide range,compared with the traditional PI control algorithm,it has better control performance.