Superconducting dynamic synchronous condenser for improved grid voltage support

Synchronous condensers are an attractive source of dynamic VARs (both inductive and capacitive) to improve system stability and maintain voltages under varying load conditions and contingencies. A synchronous condenser is a rotating machine that runs synchronized with the grid. Its field is controlled with a voltage regulator to either generate or absorb reactive power as needed by the power system. American Superconductor Corporation´s (AMSC) proprietary SuperVAR™ dynamic superconducting condenser (DSC) machines upgrade existing technology by using a conventional armature mated with a field winding made from high temperature superconducting (HTS) wires. The result is a DSC that is both more efficient and has lower maintenance than conventional machines. It can provide up to 8 pu current for short periods to support transient VAR requirements. The Tennessee Valley Authority (TVA) is sponsoring the development and field testing of an 8 MVAR prototype unit to be followed by five 10 MVAR production units. Larger units are planned for the future. This paper describes features of the DSC and its performance in grid applications.