Three-phase four-wire dstatcom with H-bridge VSC and star/delta transformer for power quality improvement

A new topology of three-phase four-wire DSTATCOM consisting of a H-bridge VSC (voltage source converter) with a star/delta transformer is proposed for power quality improvement in the distribution systems. The proposed DSTATCOM (Distribution Static Compensator) provides the voltage regulation or power factor correction by reactive power compensation along with harmonics elimination, load balancing and neutral current compensation in three-phase four-wire distribution system. The transformer has star connected primary and delta connected secondary and the load neutral point is connected to the neutral of star winding so that it provides a path to the zero sequence fundamental as well as harmonics neutral currents. This topology has the advantages of the use of two-leg, H-bridge VSC which reduces the size and cost of the DSTATCOM. The rating of the transformer is decided based on the compensating neutral current. The performance of the proposed DSTATCOM system is validated through simulations using MATLAB software with its Simulink and Power System Blockset (PSB) toolboxes.