Flexible Alternating Current Transmission Systems (FACTS) Devices

Flexible alternating current transmission systems (FACTS) make it possible to increase transmission network capacity while enhancing system flexibility, reliability, security and controllability, with limited environmental impact. This chapter, after illustrating the technical characteristics of the different families of FACTS, provides some economic and environmental figures. Planning guidelines are given for general applications, and some specific cases are described. The final goal of this chapter is to provide a complete view of FACTS from the point of view of their possible deployment in the system: this contribution is not specifically intended to provide details on electronics, for which the interested reader can consult an already wide literature. In particular, TSOs can find here a description of the key properties of FACTS and guidelines to support their decision-making, in order to determine whether and where to include FACTS devices among the possible reinforcement options in modern transmission expansion planning processes