Star/Hexagon Transformer Based Three-Phase Four-Wire DSTATCOM for Power Quality Improvement

A new topology of DSTATCOM (distribution static compensator) is proposed for power quality improvement in three-phase four-wire distribution systems. A three-leg VSC (Voltage Source Converter) is integrated with a star/hexagon transformer for the compensation of reactive power for voltage regulation or for power factor correction along with load balancing, elimination of harmonics currents and neutral current compensation. The star/hexagon connected transformer provides a path to the zero sequence current in a three-phase four-wire distribution system. In order to optimize the voltage rating of the VSC, the star/hexagon transformer is designed to have a suitable voltage rating for the secondary windings for integrating the three-leg VSC. This transformer connection provides the selection of 'off the shelf' VSC for this application and it also provides isolation for the VSC system. The performance of the proposed DSTATCOM system is validated through simulations using MATLAB software with its Simulink and Power System Block set (PSB) toolboxes.