An intelligent supervisory system for drum type boilers during severe disturbances

Severe disturbances cause a number of problems in the operation of power plants. The plant subsystem that often suffers the most is the boiler. Alleviating the severity of the problem requires improving the boilerʹs capability in dealing with disturbances. One of the more severe upsets is partial or full load rejections. Withstanding load rejections depends almost exclusively on the boiler control. This paper presents a fuzzy supervisory scheme to improve the performance of the boiler response during such disturbances. This scheme consists of a robust local controller designed using the Linear Quadratic Gaussian with Loop Transfer Recovery (LQG/LTR). The set-points to the controller are modified whenever necessary by a supervisor partially based on fuzzy logic.