Study on Main Circuit Selection and Single-phase SVPWM Algorithm of SSSC

Selection of main circuit and modulation algorithm are the key technology in SSSC. This paper proposes one main circuit structure for SSSC which is based on single phase cascaded inverters and coupling transformers by comparing with several typical main circuit structures, considering the standards for choosing main circuit such as function realization, high capability, redundancy design, efficient modulation algorithm and so on. The authors have deduced the modulation strategy for single phase on the basis of nonorthogonal coordinates according to basic circuit theory, which makes it possible for multilevel SVPWM to be applied to the modulation of single phase inverter in SSSC. Finally, the electric magnetic transient model is built depending on EMTDC/PSCAD and MATLAB by calling the modulation algorithm realized by MATLAB into EMTDC/PSCAD. As the simulation results shown, the power flow can be effectively controlled by SSSC which adopts the proposed main circuit structure and modulation algorithm. The validity of the modulation algorithm is further proved by experiment.