Zero-sequence Harmonic Suppressor Filtering in Three-phase Four-wire Systems

This paper focuses on the application of a new zero sequence harmonic suppressor for three-phase four-wire systems to suppress zero sequence harmonics. The mentioned zero-sequence harmonic suppressor consists of two integral parts, i.e., a zero-sequence filter and a zero-blocker. The zero-sequence filter is designed for non-linear loads in a three-phase four-wire system and the zero detector is designed for voltage unbalance in a three-phase grid. In this paper, the theoretical modeling and model analysis of each device is carried out, the principle of harmonic compensation is presented, and the design process of the main circuit, which simulates the working conditions of a non-linear load in a three-phase four-wire system. A simulation model is finally built in MATLAB/SIMULINK for the analysis. The simulation shows that the device can filter the zero-sequence harmonics on the neutral line, significantly reducing the current on the neutral line and improving the power quality of the system.