The impacts of FACTS and other new technologies on power system restoration dynamics

A number of years ago when FACTS applications had generated a great deal of enthusiasm, a paper was prepared predicting its applications in the power system restoration. It was predicted that many of the FACTS applications such as thyristor controlled shunt reactors, phase/voltage regulators, STATCOM, SVC, SSSC and thyristor controlled braking resistors (TCBR) were equally applicable to power system restoration. Recognizing that during restart and reintegration phases of restoration, a power system often consists of one or more islands, most of the automatic controls have tripped or deactivated, and the system is primarily under manual control. And that during these two restoration phases, transient/dynamic instability, sustained/transient over-voltages, load-generation imbalance and reactive power imbalance occur more often. It was hoped that FACTS technologies could eliminate or mitigate many of these restoration problems resulting in a significant reduction in restoration duration and damage to equipment. Not all the former paper´s predictions have materialized. This paper revisits the FACTS applications that have been developed since, and describes a number of new technologies such as PMU that also can be used in restoration.