AT C Enhancement ConsideringTransient Stability Based on Optimal Power Flow Control

Withrecentdevelopment ofpowerelectronics technology, powersystemstability enhancement andoptimal powerflowcontrol byusing Flexible AC Transmission System (FACTS)devices havesofarbeenstudied. TheFACTSdevices torelieve multiple constraints canalsomakeitpossible to enhanceAvailable TransferCapability (ATC) without construction ofnewtransmission lines. Inthispaper,a new methodforimproving transient stability byUnified PowerFlow Controller (UPFC)isproposed. Thentheproposed methodis applied toanOPFcontrol byusing UPFCforavoiding multiple constraints. ThenewOPF methodisusedforenhancement of ATC taking intoaccount transient stability constraints aswell asoverload andsteady-state stability constraints. TheOPF problemisformulated tominimize total inverter capacity of UPFC.Effectiveness oftheproposed methodisshownby numerical examplesfor3-machine 9-bussystemand 10- machine 47-bus system.