Harmonic Reduction and Load Balancing of Three Phase Four Wire DSTATCOM using three Leg VSC and A Zig Zag Transformer

Power quality problems is severe in three phase four wire distribution system such as poor voltage regulation, high reactive power burden and harmonics current, excessive neutral current, load unbalancing, etc. In this paper, the three leg voltage source converter (VSC) along with zig zag transformer was functioned as a DSTATCOM (Distribution Static Synchronous compensator).The DSTATCOM is a compensating device which is used to control the flow of reactive power in the distribution systems. In three phase four wire distribution system DSTATCOM is used for compensation of reactive power and unbalance caused by various loads in distribution system. The transformer connected in zig-zag is used for providing a path to the zero-sequence current. The IGBT (insulated gate bipolar transistor) based VSC is supported by the capacitor and is mainly controlled for the required compensation of the load current. By varying the load conditions the dc bus voltage of the VSC is regulated. The simulation results are verified using MATLAB software with its Simulink and power system block set toolboxes.