A comparison of different circuit configurations for an advanced static VAR compensator (ASVC)

Different circuit configurations for an ASVC are introduced and compared. Investigations are restricted to the stationary behavior with a brief look at parameters for dynamic control of the system. The concepts are extended to series connection of gate turn-off thyristors (GTOs), the multilevel inverter, and the application of more than one inverter. The circuits discussed show very large differences in cost and performance. Therefore, the choice for a certain application has to be made very carefully. The appropriate power rating must be reached by putting a number of GTOs in series. Paralleling of a small number of power circuits may also be considered. For common requirements concerning harmonic distortion of the line current only the best of the circuits allow operation without any filter banks. With three-level inverters and single GTOs as switches the circuits have a power rating of about 14 MVA. To reach 100 MVA would require at least eight GTOs in series