Takagi-Sugeno Observers as an Alternative to Nonlinear Observers for Analytical Redundancy. Application to a Steam Generator of a Thermal Power Plant

Two observer design approaches for analytical redundancy are presented in this work. The first one is based on the use of Takagi-Sugeno observers, whereas the second method is based on nonlinear high-gain observers. The objective is to conduct a comparative study between these two different approaches for a posteriori application of monitoring process and/or fault detection. In order to ensure a fair comparison, both approaches are evaluated on a common case study: the estimation of critical variables in a steam generator for thermal power plants. A well-known simplified nonlinear model for the steam generator proposed by Bell and strom is used for the high-gain observer design whereas for the Takagi-Sugeno obsever design, the nonlinear model is transformed into a Takagi-Sugeno form by means of the nonlinear sector approach. The main contribution is to propose the use of Takagi-Sugeno observers for analytical redundancy purposes and to highlight their advantages over the use nonlinear high-gain observers.