Control reconfiguration of a boiler-turbine unit after actuator faults

Abstract

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 reconfig uration by fault-hiding approach for a boiler-turbine unit. In Fault-hiding approach, after occurrence of a fault, 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. Three major faults are assumed to occur in three actuators of the system consisting of fuel flow valve, steam control valve and water flow valve. Faults cause the outputs of the plant to deviate from desired values and in some cases cause instability in the system. Setpoint tracking recovery and optimal performance recovery problems to diminish effects of the faults 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 since the reconfigured closed-loop system has had tolerable properties against faults.