Control of parallel EHV interconnection lines using Phase Shifting Transformers

Abstract

Power systems interconnected with Extra High Voltage tie-lines are prone to unscheduled power flows. This paper investigates how to control these flows in parallel EHV interconnection lines using Phase Shifting Transformers (PST). A phase-angle regulated PST placed in a longitudinal transmission network is modeled. A real system application concerns the Tunisian-Algerian 400kV/225kV parallel interconnections. Different placement locations, operating scenarios, and control options are tested. The PST based solutions are discussed in terms of power flow control, voltage support and economic aspects.