Line congestion relief using UPFC

Congestion is a growing problem in the modern power system, as systems are interconnected and are always operating near stability limit which results in rapid voltage drop due to heavy load demand. Unified Power Flow Controller (UPFC) is one of the latest generation Flexible AC Transmission System (FACTS) devices, which is able to control simultaneously or selectively, all the parameters affecting power flow in the transmission line. This paper presents a suitable location of UPFC, for retaining the stability margin. Line voltage stability index is used to identify the critical lines under the condition of congestion, where UPFC has been installed. Results are shown in context to IEEE-14 bus system using MATLAB software.