Damping performance analysis of IPFC and UPFC controllers using validated small signal models

Summary form only given: The paper discusses the dynamic behaviour of two different Flexible AC Transmission System (FACTS) devices; the Interline Power Flow Controller (IPFC) and the Unified Power Flow Controller (UPFC) in a benchmark system. The small signal model of the Interline Power Flow Controller (IPFC) is developed and validated using detailed electromagnetic transients simulation. Using this validated model, the damping capabilities of the IPFC and the UPFC are compared and rationalized. From a small signal dynamics point of view, it is shown that the series branches of these devices essentially segment the network creating a new structure. This structure change may be used to effectively improve system damping without requiring the design of a tuned feedback controller. The IPFC´s two series branches in contrast to the UPFC´s single series branch permit more opportunities for network segmentation. Hence the IPFC has a greater potential for improving the systems dynamic performance.