Neutral current and harmonic mitigation using ZSBR with various transformer topologies

Abstract

Mostly all domestic and commercial installation uses 3-phase 4-wire distribution system, but pretty much appliances are single phased which may create unbalance in the supply system also typical loads like TV, personal computers, mobile phone chargers, Air conditioners etc. uses power electronic converters and draws non-sinusoidal currents, these two situations may cause high neutral current and create harmonics in the supply system. It may cause wiring failures, rising of neutral potentials, transformer overheating, etc. In response to this problem, this paper proposes some passive compensation methods for minimizing the neutral current and harmonics in the three-phase four-wire distribution system. The proposing methodology using combinations of ZSBR with various transformers like T-connected transformers, star delta transformer, Scott connected transformer, star polygon transformer and star hexagon transformer. In this paper, analysis is carried to evaluate the performance of various transformers in combination with ZSBR under unbalanced and non-linear loads. The simulation results shows that the neutral current is reduced to negligible value and the total harmonic distortion has been reduced below 50% as in the supply lines.