Installation, commissioning, and operation of the world´s first UPFC on the AEP system

A major thrust of FACTS is the development of systems that control power flow by changing the impedance of a transmission line or phase angle between the ends of a specific line and also controlling the voltage at critical busses. The Unified Power Flow Controller (UPFC) is a novel concept which offers multiple compensation functions for power transmission systems. The UPFC is capable of controlling the three basic transmission parameters (voltage, line impedance, and phase angle). Thus, the UPFC allows flexible control of both active and reactive power flows on transmission corridors. American Electric Power (AEP) has selected its Inez substation in eastern Kentucky for the location of the world´s first UPFC installation. The UPFC is comprised of two ±160 MVA voltage-sourced GTO thyristor-based inverters, this installation is not only the first practical demonstration of the UPFC concept, but also by far the highest power GTO-based FACTS device ever installed. The two inverters can be decoupled and operated separately, one as a static compensator (STATCOM) and the other as a static synchronous series compensator (SSSC). Normally, they will be operated as a UPFC to regulate terminal bus voltage an simultaneously control power flow. This paper focuses on the UPFC equipment, challenges and the significant achievements that were made during the construction, commissioning tests, and the UPFC operational experience. This project is a collaborative effort between AEP, the Westinghouse Electric Corporation and the Electric Power Research Institute (EPRI)