Delta — Wye transformer based triplen harmonic trap for three phase rectifier to mitigate THD using PSCAD

The 3-phase diode bridge rectifier has the least line current distortion among 6-pulse rectifiers; however, its total harmonic distortion (THD) of 31.08% violates power quality standards. This paper reports distortion reduction by lowering magnitudes of harmonics in the line currents using a delta-wye transformer between the 3-phase utility and the diode bridge rectifier. The leakage inductances of the transformer windings provide a filtering effect on the line current harmonics thus providing THD mitigation of utility line currents. The efficacy of the technique is proved by Power System Computer Aided Design (PSCAD) simulations considering the bridge rectifier with and without the delta-wye transformer of vector group Dy1. Experimental results without and with the Dy1 transformer feeding the diode bridge rectifier are presented.