Observer-based decentralized optimal controller design of PSS and TCSC for enhancement of power system dynamic stability

This paper deals with the decentralized control scheme and its application to the multi-machine power systems. Due to the geographically distributed nature of the power system, the decentralized control scheme may be more feasible than the centralized control scheme. In this study, an observer-based decentralized optimal control scheme for power system stabilizers (PSS) and thyristor-controlled series capacitors (TCSC) is presented and tested in the WSCC 9-bus system with one TCSC installed. In addition, using modal analysis, this paper identifies the eigenvalues that each decentralized controller significantly affects. From this study it is found that the decentralized control scheme has potential advantages to enhance the power system stability when each low-damped mode occurs dominantly by each decentralized subsystem, which is the general case in power systems.