Abstract
Unified power flow controller (UPFC) is one of the Flexible ac Transmission System (FACTS) devices that possess the ability of modulating both active and reactive power at the point of common coupling in four quadrant operational modes. This chapter illustrates UPFC topology, controllers with some case studies for various applications of UPFC in the DFIG-based WECS. New applications for UPFC are proposed to improve the overall performance of a DFIG-based WECS during voltage sag and voltage swell events at the grid side.
Keywords: FACTS, UPFC, Active and reactive power modulation, Power system stability.