Wavelet-Based Identification for Control of Watertube Drum Boilers

Abstract

The procedure for identifying linear time-varying systems with dead times using the wavelet analysis has already been proposed by the authors. This paper reports an application of the identification procedure to actual control systems of watertube drum-boiler in a thermal power plant. The control systems are required to supply steadily high-quality steam subject to disturbances due to unexpected changes in load. Therefore, it is necessary to make a precise model which takes the disturbances into consideration for control system design. The identification procedure is applied by the following steps: (1) extension of the method for single-input/output systems to that for two-input/output systems, (2) estimation of the time span where the system is considered to be in steady states, and (3) estimation of the process transfer functions in each time span. The identified model is evaluated in terms of mean square errors of the process outputs (steam-pressure and water-level) in comparison with an ARX model. © 2002, The Institute of Electrical Engineers of Japan. All rights reserved.