A Zig-zag Transformer based Hybrid Power Filter with Cascaded Three level Multilevel Inverter to Enhance Power Quality in Three-Phase Four-wire Distribution Power System

Abstract

In distribution power systems, due to nonlinear loads, harmonic currents are induced. These harmonic currents increase the losses in the distribution transformer which in turn reduce the efficiency. The Unbalance loading also results in neutral line current, which is undesirable. In worst case of the loading, the neutral line current is twice the rated current which it can melt the neutral conductor of the distribution transformer. Different types of filters with different configurations are used to reduce the Total Harmonic Distortion (THD) and neutral line current. But the drawbacks of the existing filters will result in high THD, high DC link voltage and high filter currents. In this paper, a zig-zag transformer based Hybrid power filter with Neutral point clamped (NPC) three level multilevel inverter is used to reduce the neutral conductor current, harmonic currents, DC link voltage across capacitor and filter currents. The validity of the model is verified using MATLAB simulation results.