Intelligent coordinated control of circulating fluidized bed boiler-turbine unit

An intelligent coordinated control strategy has been proposed and successfully applied to 135~300 MW circulating fluidized bed (CFB) boiler-turbine units in China. Because the combustion system of the CFB is a complex object characterized, it is difficult to build precise mathematic model and control it with traditional control theory. The paper describes intelligent coordinated control (ICC) system for the circulating fluidized bed (CFB) unit. ICC is based on both fuzzy feedforward control and the fuzzy-PID feedback control. The feedforward control path contains a set of multi-input single-output fuzzy inference systems. The control output is mainly determined by the feedforward path, diminishing the control effort on the PID controllers. The fuzzy-PID controller supplies the complementary control signal component for regulation and disturbance rejection in small neighborhoods about the commanded trajectories. The scheme is implemented based on the Function Code on many typical DCS (INFI-90, XDPS, etc). The industrial application results show that this design scheme works well for the specific range of load variations.