Active disturbance rejection control for Circulating Fluidized Bed Boiler

The Circulating Fluidized Bed Boiler (CFBB) is a multivariable coupled, long time-delay, large inertia system. In this paper, a decentralized control system using active disturbance rejection control (ADRC) strategy is proposed for a nonlinear CFBB model. The designed control system has a fully decentralized structure and it is free of complex decouplers, which is difficult to achieve in actual plants. With ADRC method, the interaction of two control loops, the higher orders, uncertainties and unmodeled dynamics are treated as general disturbance, which is estimated by Extended State Observer (ESO) and then actively compensated. Some simulation results illustrate that the designed control system has good performance when the power set point is varied in a wide range and a disturbance of the set point of main steam pressure is added into the CFBB system. Besides, the same parameters are adequate on varied operating points, indicating the strong robustness of the controller. The proposed decentralized control system has advantage in easy tuning procedure, simple structure and its disturbance-rejection capability.