Damping improvement and terminal voltage regulation for a synchronous machine using an energy storage device

Abstract

On the basis of the non-linear third-order generator model, this article proposes a dual control scheme for a single synchronous machine equipped with an energy storage device to regulate the terminal voltage while enhancing the damping. Based on the input-output feedback linearisation method, the exciter controller is designed such that the terminal voltage robustly converges to its predetermined reference in the presence of a model uncertainty. In addition, the control input of the energy storage device feedbacks only the relative speed. It is shown that this controller can effectively increase the damping of the synchronous machine and that there is a set of initial conditions such that all trajectories started from this set go to the equilibrium point, satisfying input constraints. Moreover, it is also verified that all generator variables are bounded except for the power angle. The simulation results show that the closed-loop performance is satisfactory despite a transmission line fault and a model uncertainty in which the non-linear fourth-order generator model (two-axis) is used.