Predictive Sliding Mode Control on Bed Temperature of CFB Boilers

To tackle the uncertainties caused by variations of load, coal and environmental conditions as well as by model simplification, a predictive sliding mode control strategy, which is easily understandable and applicable in practice, was proposed for the thermal processes with large inertia or time delay. Firstly, a predictive model without output delay was established to estimate the process output by using a second-order plus dead-time (SOPDT) model obtained in nominal case. Secondly, a reasonable sliding function and a sliding mode control law with adaptively estimated uncertain upper bound were designed to asymptotically stabilize the closed-loop system with uncertainties and disturbances. On the basis above, numerical simulations were conducted on bed temperature of a circulating fluidized bed (CFB) boiler. Results show that the control strategy proposed is fast in bed temperature regulation with small overshoot and strong anti-disturbance capability.