In 1995 a /spl plusmn/100 MVA static synchronous compensator (STATCON) was commissioned for the Tennessee Valley Authority (TVA) at the Sullivan substation in North-Eastern Tennessee, USA. This was an historic milestone in the initiative for flexible AC transmission systems (FACTS) promoted by the Electric Power Research Institute (EPRI). The TVA STATCON is the first of its kind, using GTO thyristor valves, to be commissioned in the United States, and is currently the largest installation of this type in the world. Commissioning tests have now been completed and the STATCON is operating continuously online. The demonstrated performance of the equipment has either met or exceeded expectations in all areas and has proven beyond doubt the viability of this type of equipment in high power transmission systems. This paper briefly reviews the STATCON installation and reports on the static and dynamic performance observed during commissioning.