A practical approach to minimize the zero-sequence current harmonics in power distribution systems

In this paper, a simple and practical approach to minimize the zero-sequence current harmonics in three-phase four-wire power distribution systems is proposed. The zero-sequence current harmonics are minimized by using a combination of a very low zero-sequence impedance transformer and a very high zero-sequence impedance transformer. The very low zero-sequence-impedance transformer is shunt connected to the load and the very high zero-sequence impedance transformer is series connected to the source. The series connected transformer will act as a zero-sequence current isolator between the source and load and, therefore, almost all of zero-sequence currents which are generated by the load will flow through the shunt connected transformer. Experimental results are included to verify the proposed approach