A modified DSTATCOM topology with reduced VSI rating, DC link voltage, and filter size

Rating of voltage source inverter (VSI) and size of the interfacing filter are two important issues while implementing DSTATCOM. In this paper, a new DSTATCOM topology has been proposed which simultaneously reduces the rating of VSI as well as size of interfacing filter with enhanced current compensation capabilities. A capacitor is used in series with interfacing filter to reduce the dc link voltage of the DSTATCOM. Therefore, rating of VSI gets reduced as it is directly proportional to dc link voltage. To reduce the size of interfacing filter, an LCL filter has been used. An LCL filter provides excellent switching harmonics elimination capability while using much smaller value of inductor as compared to conventional L filter. A smaller inductance will cause small voltage drop across it which in turn further reduces the size of dc bus voltage and consequently VSI rating. Therefore, proposed topology will reduce weight, cost, rating, and size of the DSTATCOM with enhanced current compensation capability compared to conventional topology. A procedure to design LCL filter parameters and series capacitor has been presented. Effectiveness of the proposed DSTATCOM topology over traditional topology is verified through extensive simulation using PSCAD/EMTDC.