T.R. Rangaswamy, J. Shanmugam, and K.P. Mohammed
Combustion control, air/fuel ratio, adaptive error, turbine inlet pressure, fuzzy tuner
This article deals with the proposed design of adaptive fuzzy tuned PID controller for combustion process in utility boiler. Advanced PID controllers are designed separately for fuel and air to regulate the inputs to the utility boiler in proper ratio and maintain the desired steam pressure at the turbine inlet, irrespective of the change in steam demand. Online adaptive error factor for tuning the PID controller for fuel is presented as per the boiler dynamics, considering turbine first-stage pressure and throttle pressure. Online adaptive error factor to tune the PID controller for air is presented by measuring oxygen in the flue gas path at the outlet of the boiler economizer. The gains of the PID controllers are adjusted online in accordance with the adaptive fuel and air error factor using fuzzy logic tuning scheme. The real-time studies were carried out on the lab scale experimental set-up using conventional PID and adaptive fuzzy tuned PID control strategies. The robustness of the adaptive fuzzy tuned PID control scheme is demonstrated for both positive and negative changes in the set point as well as in the load perturbation. The performances of all the control schemes are compared quantitatively using both time domain specifications and error integral criteria. The implementation of an adaptive fuzzy tuned PID control scheme for air and fuel flow for combustion in utility boiler gave better results than conventional PID scheme.
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