Control reconfiguration of a boiler-turbine unit after actuator faults

Boiler-turbines are one of the most important parts in power generation plants. The safety problem in such systems has always been a special concern. This paper discusses the application of control reconfiguration by fault-hiding approach for a boiler-turbine unit. In Fault-hiding approach, nominal controller of the system remains unchanged; instead, a reconfiguration block is designed and placed between nominal controller and faulty plant to modify input signals when an actuator fault occurs. Setpoint tracking recovery and optimal performance recovery problems in order to diminish effects of actuator faults in the system are investigated. The results of simulations show that the reconfiguration has been successful in both cases and also confirm the applicability of the method for the boiler-turbine unit. In this paper, control reconfiguration by fault-hiding approach is used to minimize actuator faults harmful effects in a boiler-turbine unit. It is assumed that, diagnosis task has been solved already and the faulty actuator has been detected properly. The main advantage of fault-hiding approach over other reconfiguration methods is that the nominal controller of the system remains unchanged; therefore, pre-designed important features of the main controller are still available in closed loop system after reconfiguration. The paper is organized as following. In section II boilerturbine unit model, nominal controller and actuator faults modelling are introduced. In section III fault-hiding approach and its structure are discussed and also a new reconfiguration block is presented. In section IV Application of the proposed block on boiler-turbine unit and simulation results are presented. Finally, conclusion notes are in section V.