Design of a fault tolerant control scheme based on sliding mode for Canadian supercritical water reactor
Canadian Super Critical Water Reactor (SCWR) is one of the Generation IV reactor types and possible heat source for co-hydrogen production through copper chlorine thermochemical cycle. To maintain the balance between the hydrogen production and electricity production effectively and to utilize the waste heat more efficiently, a well-designed control system for the Canadian SCWR is needed. The SCWR is a nonlinear and strongly coupled multiple-input multiple-output (MIMO) plant. Traditional controller design method, which divides the MIMO system into subsystems and then designs each controller separately, will not obtain satisfactory performance. To accomplish different control objectives of different system variables simultaneously, an integrated multivariable control strategy is needed. Furthermore, as a highly safety-critical system, it is desired that safe and stable performance of the plant can be maintained even in faulty situations. A sliding mode-based Fault Tolerant Control (FTC) scheme, which includes a robust multi-input multi-output controller, a Fault Detection/Isolation (FDI) module and a Fault Accommodation (FA) module, is designed for the overall Canadian SCWR plant in this study. The simulation results indicated that compared to previous control scheme design, better performance was obtained in terms of tracking speed, accuracy, decoupling capacity and control effort in the fault free case. In the faulty case, fault information can be detected and estimated. Acceptable tracking performance was maintained and the variation of steam temperature within design limit was guaranteed.