The most crucial approach for power and control system implementation is optimal power flow because it yields the lowest operating costs and maintains the safety margins for the control variables. An essential component of the flexible AC transmission system (FACTS) is the unified power flow controller (UPFC). It is designed to provide multiple types of energy system compensation and can be utilized for controlling the reactive and active electrical power in transmission lines and bus voltages independently and at the same time. Considerable studies have been published in the UPFC engineering applications area using various techniques. Due to its versatile capabilities, UPFC is recognized as one of the most promising FACTS devices for modern power systems. UPFC is used to improve reactive power mismatch control and system stability. A brief review of UPFC applications for increasing power system flexibility and controllability has been conducted and summarized. This paper also discusses the utilization of artificial intelligence in the placement of UPFC in power systems. تفاصيل المقالة