A modified nonlinear damping of zero-dynamics via feedback control for a STATCOM

Abstract

Recently linearization via feedback control law for a STATCOM to minimize the internal dynamics oscillations was proposed. The ripples of the internal dynamics correspond to the oscillation of the current ripple on the DC side capacitor so that it affects the lifecycle of the capacitor. In this paper, a modified nonlinear damping of zero dynamics via feedback control for a STATCOM is proposed. The proposed nonlinear feedback controller improves the stability of the internal dynamics. The controller gives the damping on zero-dynamics via the nonlinear feedback controller optimized at each operating point. It guarantees internal stability in all operation regions by moving the poles of the internal dynamics away from the imaginary axis. This effect is validated through the root locus analysis. Simulation results show that the oscillation of the internal dynamics is effectively reduced using the averaged and the topological model.