抄録
A novel main circuit topology of transformer-less series voltage sag compensator is proposed. The sagged voltages are compensated by half bridge inverters, which are directly connected in series with the residual voltages and are charged by the residual line-to-line voltages. The proposed compensator can compensate symmetrical three-phase sags down to 37%, or one or two phase sags down to zero if at least one phase is rated voltage. Besides the excellent compensation property related to the compensating depth, the proposed system only need small capacitance in the inverters because they are continuously charged by the residual voltages during the sags. In fact the capacitors are not energy storers but filters, so there is no limit on their compensating time interval. Theoretical analysis is done and the concerned results are derived. Simulation results on resistance loads demonstrated the compensating performances.
