Pulse width modulated series compensator

In recent years, several power electronics based technologies, such as the thyristor controlled series capacitor and the unified power flow controller, have been introduced to provide active control of power flow through transmission lines. They have been prompted by the need to utilise existing lines up to their thermal limits to feed power to an increasing load demand, while maintaining adequate stability margins. In this paper, an alternative for electronically controlled capacitive compensation of a transmission line is presented. The proposed compensator incorporates an AC-AC power converter utilising pulse width modulation and provides accurate power flow control through the transmission line. Operating principles of the compensator are presented along with EMTP simulations demonstrating operation of the compensator.