Passivity-based control with nonlinear damping for STATCOM system

This paper describes a nonlinear controller for a static synchronous compensator (STATCOM). A passivity-based controller (PBC) using the Euler-Lagrange form is proposed for this system. The proposed PBC consists of a feedforward part and a feedback part. The feedforward part is generated from the dynamics equation of the STATCOM system. The feedback part is designed based on the Lyapunov function, thus guaranteeing the exponential stability of the equilibrium point. In inductive operating mode, the system with the PBC experiences undesirable transient response oscillations. To achieve improved performance in terms of the time-response, a PBC with nonlinear damping is proposed. The simulation results show that the proposed control method has the effect of reducing the oscillatory responses. Furthermore, the global exponential stability of the system is guaranteed by using the Lyapunov theorem.