Control Schemes and Transient Characteristics of a High Speed Phase Shifter for Power Flow Control in Power Transmission Systems

In recent years, attention has been paid to the concept of FACTS (Flexible AC Transmission Systems), along with significant progress in power electronic technology. A high speed phase shifter, which is one of the most promising devices in the FACTS concept, has the potential of power flow control and/or voltage stability in power transmission systems.In this paper, theory and experiment reveal that conventional high speed phase shifters may cause power swing in a transient state as a result of coupling between instantaneous active and reactive power control loops. Then, a couple of new control schemes for a high speed phase shifter are proposed to achieve both power flow control and power swing damping. The second proposed control scheme is based on the control scheme of an already proposed series active filter. Simulated and experimental results agree well with analytical results, not only in steady states but also in transient states.