A three-leg inverter based DSTATCOM topology for compensating unbalanced and nonlinear loads

This paper proposes a new three-leg voltage source inverter (VSI) based distribution static compensator (DSTATCOM) topology to compensate unbalanced and nonlinear loads in low voltage three phase four wire distribution systems. The proposed topology uses a three-leg VSI with a single DC storage capacitor and an additional capacitor which is connected between negative DC bus to the system neutral. As the proposed topology uses a single DC link capacitor, the DC voltage balancing issues associated with the popular split capacitor neutral clamped VSI topology is avoided. Moreover, the topology is able to compensate neutral current without using four-leg inverter topologies. Analysis and modelling of the proposed topology is explained in detail. Simulation studies are carried out to verify the performance of the proposed schemes and results are presented.