Experimental investigation of harmonics in line and neutral currents of 3-phase utility feeding 2-pulse rectifiers

In the commercial sector single-phase, non-linear loads are predominant and their numbers are on the increase. The two-pulse diode bridge rectifier is the most popular single-phase topology deployed for ac-dc conversion of electrical energy; however, when feeding an inductive load, its line current has a total harmonic distortion of around 28%, that is a gross violation of contemporary power quality standards. Another concern is the presence of triplen harmonics including the third, in the line current, that add up in the neutral conductor. This paper reports distortion reduction by elimination of triplen harmonics and mitigation of non-triplen harmonics in the line and neutral currents using a delta-wye transformer between the three-phase utility and the diode bridge rectifiers. The efficacy of the technique is proved by experimental data and power quality measurements.