The design, modeling and control design of a 48-step inverter based static
synchronous series compensator (SSSC) is presented in this paper. A magneti
c circuit is chosen which contains eighteen single-phase three winding tran
sformers and six single-phase two winding transformers to add the output vo
ltages of eight three-phase inverters, An equivalent circuit model of the S
SSC is derived and based on this model a proportional-plus-integral control
ler is proposed. The controller gains are chosen through eigenvalue analysi
s of the IEEE first benchmark model for subsynchronous resonance (SSR) anal
ysis. The SSSC model, its control and the results of the eigenvalue analysi
s are then validated through PSCAD/EMTDC simulation. It is shown that for c
ertain controller gains torque amplification of the shaft modes can occur.