Time-optimal series capacitor control for damping interarea modes in interconnected power systems

Controllable series capacitors have been proposed to damp power swings resulting from large transient disturbances in systems with two machines. In this paper we propose a time-optimal series capacitor control to damp interarea modes in multi-machine systems. To find the switching line, we apply the slow coherency transformation to the full system and project a slow subsystem trajectory found from the trajectory reversing method onto the predominant interarea mode. The method is illustrated by the time simulation of a six-machine power system with two interarea modes and is shown to give the desired result. Keywords - transient stability, time-optimal control, series capacitor, interarea modes, switching line