Development of a ±100 MVAr static condenser for voltage control of transmission systems

The availability of high power gate-turn-off (GTO) thyristors has led to the development of controllable reactive power sources, using electronic switching power converters, for use in power transmission systems. This new technology has resulted in equipment that is fundamentally different from the conventional thyristor-controlled static VAr compensator (SVC). The new equipment is called a static condenser (STATCON) because its steady state output characteristics are similar to those of the rotating synchronous condenser. The paper describes the fundamental operating principles, functional characteristics and basic control approach of the STATCON, with particular reference to a ±100 MVAr prototype planned to be installed at the Tennessee Valley Authority (TVA) Sullivan substation, USA. This installation will be the first demonstration of a STATCON under the EPRI flexible AC transmission systems (FACTS) program, and will be the largest installation of its type in the world