Survey and crossed comparison of types, optimal location techniques, and power system applications of FACTS

Flexible AC Transmissions Systems (FACTS), developed during the last decades of the past century, have become one of the most remarkable solutions for the optimization of the electricity grid. Different types of FACTS have been proposed to solve similar transmission system operation problems. This paper reviews the FACTS devices used for solving these problems and the techniques used to optimize their location. The objective of the paper is to serve as a guide for selecting the right power system analysis and optimization techniques for a given transmission system problem, and the most used FACTS for this purpose. The main operation issues that have been considered are: voltage control, assets optimization, line overloads and grid congestion, voltage stability problems, angle stability problems, contingencies and economic issues. The study classifies the optimization methods in four groups, analyses their applications and extracts several conclusions from the bibliography analyzed and the actual state of the market for FACTS.