Modeling and control design of a static synchronous series compensator

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.