Load following control of a PWR with load-dependent parameters and perturbations via fixed-time fractional-order sliding mode and disturbance observer techniques

This paper is concerned with the fixed-time fractional-order sliding mode control (FTFOSMC) approach using fixed-time disturbance observer (FTDO) for the load following problem of a pressurized water reactor (PWR), in the presence of load-dependent parameters and perturbations. First, by integrating the merits of the fixed-time stability theory and the disturbance observer technique, an FTDO which can ensure fixed-time convergence is constructed to estimate perturbations induced by model uncertainties, external disturbances, and unmeasured states. Then, an FTFOSMC strategy with the help of the disturbance observer is proposed to achieve strong robustness against perturbations and high-precision load following performance. The fixed-time stability of the closed-loop system is theoretically demonstrated by Lyapunov’s theorem. Finally, comparative simulation results are presented to illustrate the superiority of the overall proposed control strategy.