Decentralized PI control with improved disturbance observer for power plant fluidized bed combustor

A compound control strategy is proposed to handle the nonlinear dynamics existing in the power plant fluidized bed combustor (FBC). Based on the linearized model of the FBC, two improved disturbance observers (DOB) are proposed to accommodate the characteristics of time-delay and non-minimum phase (NMP) characteristics. The capabilities of the disturbance observer to handle load disturbances are also analyzed. By implementing DOB, the nonlinear combustion process can be approximated as a nominal linear model which is suitable for the varying working conditions. Finally, decentralized DOB-enhanced PI controllers are designed for the corresponding linear models for power and temperature loops. The global simulation and comparison with Model Predictive Control and conventional multi-loop scheme demonstrate that the scheme proposed is feasible and effective.