OBSERVERS FOR BILINEAR-SYSTEMS WITH UNKNOWN INPUTS AND APPLICATION TOSUPERHEATER TEMPERATURE CONTROL

This paper considers the problem of controlling the steam temperature of a superheater with a desuperheater. Since the metal temperature is usually not available for measurement, it is regarded here as an unkno wn input, and a bilinear unknown input observer is designed. A suffici ent condition for the asymptotic stability of the proposed observer is derived, and the design of a state feedback controller is based on th e proposed observer. Computer simulations show that the estimated valu e follows the superheater steam temperature under the variation of the external inputs, and that the outlet steam temperature is properly ma intained, and a comparision with a PI controller is made. Copyright (C ) 1997 Elsevier Science Ltd.