Nonlinear controller design for hydraulic turbine regulating systems via immersion and invariance

Abstract

This paper proposes a nonlinear controller strategy for the frequency regulation of a hydraulic turbine regulating system (HTRS). An immersion and invariance (I&I) technique is utilised to develop the desired control law. The derived control method is used to guarantee that the equilibrium point is asymptotically stable. Furthermore, it can ensure that all overall closed-loop system trajectories are bounded. The feasibility and effectiveness of the technique are demonstrated using a nonlinear dynamical system of an HTRS connected to a single-machine infinite bus (SMIB) power system. The simulation results demonstrate that the technique is capable of regulating the frequency and improving dynamic performance despite large disturbances. It is capable of rapidly reducing oscillations and surpasses two known nonlinear controllers, namely the synergetic control and the backstepping control techniques. Additionally, despite the fact that the HTRS's parameters vary, the proposed technique is capable of providing consistent control performance. As a result, the presented controller is insensitive to variations in the system's parameters.

Keywords:

• Nonlinear control
• immersion and invariance control
• hydraulic turbine regulating system
• renewable energy

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

1 It is assumed that all functions and mappings are smooth, i.e. ${\mathbb{C}}^{\mathrm{\infty }}$, throughout this paper.