A bidirectional 18-pulse voltage source converter utilizing gate turn-off thyristors (GTO's) is described. The converter, which is rated 10 MVA, was placed in service in early 1988 to connect an energy storage battery to a utility grid. The converter is rated and controlled to operate in all four quadrants (discharge, charge, leading vars, or lagging vars) at the full 10-MVA rating. It is capable of independent rapid control of real and reactive power with a transient response of 16 ms to changes in commanded value of real or reactive power. Thus it is usable as a reactive power controller (static var control), voltage control, frequency control, power system stabilizer, or as a real power peaking station. For use as a reactive power controller only, no battery would be needed. The design, construction, control, and application of the converter are described, and performance data taken at factory power test and at the installation are given. © 1990 IEEE
