Actuator Fault Compensation Based on a Takagi-Sugeno PI Observer: Application to a Thermoelectric Steam Generator

International audienceIn this paper, a fault-tolerant control scheme is presented for a boiler-turbine unit of a thermal power plant covering a wide range of operations: at low, medium, and high loads. The approach is based on the use of an observer-based actuator fault estimation system to detect and estimate the fault magnitude for a posteriori compensation via a fault-tolerant control scheme. The performance of both, the observer for actuator fault estimation and the fault-tolerant control scheme are evaluated in a practical scenario using a simulator of the dynamics of the critical variables of the process: the main steam flow, the first stage turbine pressure, the super-heated steam pressure, the drum pressure, and the electric power. The main contribution of this work is to develop an integral, practical methodology for analysis and design of a simultaneous actuator fault estimation and fault-tolerant control system for nonlinear processes. The originality with respect to other works is the regulation of the electric power demand in a thermometric steam generator by means of a fault-tolerant control (FTC) approach. The FTC is based on the knowledge of the fault magnitude on actuators via an observer-based fault estimation scheme. On the other hand, the use of the Takagi-Sugeno approach allows to extend these results to a wider variety of processes with strong nonlinear dynamics