In three-phase four-wire distribution network,the neutral wire,ground wire and repeatedly grounding of the neutral evidently impact the power flow distribution and the convergence of power flow algorithm,however,in existing references the research results in this field is seldom reported.

The single earth-fault in three phase network earthed neutral is called as single phase short circuit, and that in three phase network insulated to earth is called as leakage fault.

Based on the result that transformer can transform travelling waves effectively,this paper researches the transform characteristic of travelling waves in three-phase distribution transformers.