Linear matrix inequality versus Root-locus approach for damping inter-area oscillations in power systems

This paper describes the merits of robust damping controllers designed using a Linear Matrix Inequality (LMI) approach as compared to conventional Root-locus technique. The design in both methods aims at improving the damping of inter-area modes employing two small superconducting magnetic energy storage (SMES) devices. The LMI based control ensures adequate damping for widely varying system operating conditions and is compared with that obtained by the root-locus technique. It is shown that the LMI based approach has advantages over root-locus based control for the same control effort.