Application of hybrid fuzzy logic proportional plus conventional integral-derivative controller to combustion control of stoker-fired boilers

Combustion control of an industrial stoker-"red boiler is to provide a continuous supply of steam at the desired condition of pressure. Because no e$cient mathematical model of the stoker-"red boiler is available, it would be very hard to design its controller by using any traditional model-based method. Therefore, the most widely used controller for the boiler system is a conventional PID-type controller due to its simple control structure and ease of design. However, control performance of the PID-type controller su!ers greatly from high uncertainty and nonlinearity of the system, large disturbances and so on. This paper presents a hybrid fuzzy logic proportional plus conventional integral-derivative (FUZZY P#ID) controller to improve the control performance yielded by the PID-type controller. The proposed FUZZY P#ID controller is constructed by using an incremental fuzzy logic controller in place of the proportional term in the conventional PID controller. The basic idea of this study is to reduce the parameters of a fuzzy controller to be tuned so that, in comparison with the PID-type controller, only one additional parameter should be adjusted. The proposed hybrid FUZZY P#ID controller is applied to several stoker-"red boilers. In order to demonstrate the e!ectiveness of the hybrid controller, the real application results on control of the stoker-"red boilers are reported and analyzed. ( 2000 Elsevier Science B.V. All rights reserved.