IcosΦ algorithm based control of zig-zag transformer connected three phase four wire DSTATCOM

In this paper, an IcosΦ algorithm based new DSTATCOM (Distribution Static Compensator) using three-leg VSC (voltage source converter) integrated with a zig-zag transformer is investigated for the power quality improvement in three-phase four-wire distribution systems. The zig-zag transformer is used for providing a path to the zero sequence fundamental as well as harmonics currents. In order to optimize the voltage rating of the VSCs, the zig-zag transformer is designed to have a tertiary winding for integrating the VSC. This new DSTATCOM provides the voltage regulation or power factor correction by reactive power compensation, harmonics compensation, load balancing and neutral current compensation in three-phase four-wire distribution system. The reference currents for the DSTATCOM is estimated using the IcosΦ algorithm and this is simple and with reduced computations. The performance of the proposed DSTATCOM system is demonstrated under linear and nonlinear balanced and unbalanced loads by simulation using MATLAB with its Simulink and simpower systems (SPS) tool boxes.