Universal finite‐time observer design and adaptive frequency regulation of hydraulic turbine systems

Abstract

In this study, the authors consider the problem of frequency regulation via output feedback for a hydraulic turbine system under unknown load variations. First, to address the difficulties in estimating the unmeasurable states and the unknown load variation, they introduce a universal finite-time observer (UFTO) which can estimate unmeasurable states, unknown parameters and disturbances under a unified framework. Based on the proposed UFTO, the unmeasurable wicket gate position, the flow rate and the load variation are estimated in a finite time for the hydraulic turbine system. Then by introducing a coordinate transformation, the state-space model of hydraulic turbine system is converted into a simple form for which a state feedback control law is constructed using the adding a power integrator approach. Combining the UFTO with the finite-time control law, an output feedback controller is designed to regulate the frequency of the hydraulic turbine system. Computer simulations are also given to validate the proposed finite-time output feedback controller.