PSS design for the Hellenic System with partial interconnection to Turkey

This paper describes the effects on the interarea modes of the Hellenic power system of its radial connection with an isolated generating area in the European part of Turkey. It is shown that significant mode shape changes occur and poorly damped power oscillations may appear between Greece and Turkey involving also the interconnection of Greece to the North. Two possible system operation cases are studied: case A with all lines in operation (strong connection), and case B for a weak interconnection due to a critical line outage in the North East of Greece. Analysis shows that a near strong resonance occurs in the latter case. A power system stabilizer (PSS) is designed for a Hellenic generation plant mainly involved in the poorly damped oscillation modes and is able to restore adequate damping in all cases.