Fixed-time command-filtered backstepping control design for hydraulic turbine regulating systems

Abstract

A novel practical fixed-time command-filtered backstepping strategy for a hydraulic turbine regulating system (HTRS) is developed in this paper. The developed controller is designed with the help of a combination of command-filtered backstepping and practical fixed-time stability theory. Based on this scheme, the obtained control strategy is utilized to ensure that the equilibrium point is practically fixed-time stable, and all signals of the closed-loop system are bounded within a fixed time. The main contributions of this paper are threefold: (i) The control scheme for frequency regulation of the HTRS is proposed to deal with the problem of the “explosion of terms” caused by conventional backstepping design. (ii) The proposed practical fixed-time control law can guarantee superior stabilization with a more precisely bounded convergence time, and (iii) The proposed controller performs well, simultaneously offers better transient performance, and overcomes three important drawbacks arising in the current results of fixed-time synergetic controllers. The strategy's effectiveness and feasibility are validated in a nonlinear model of the HTRS connected to a single-machine infinite bus power system. The numerical simulation indicates that the frequency regulation and improved transient performances in fixed time are achieved based on the proposed strategy. Further, the presented control reduces the oscillations rapidly and performs better than fixed-time synergetic control and modified fixed-time synergetic control approaches.