Experimental and computational analysis of effects caused by voltage variations on ground return single-phase distribution systems: zero sequence harmonics and impacts

In order to attend small rural consumers, the ground return single-phase distribution systems emerges as an attractive solution. The existence of such system implies in peculiar operative conditions. In this way, this paper is focused on studies related to medium voltage distribution system supplying a great amount of ground return single-phase circuits and its side effects. The aim is to investigate the causes of high values of voltage and current at the transformer´s neutral conductor existent at the substation and corresponding effects. In order to clarify the phenomenon, tests for typical single-phase transformers used in commercial single-phase systems are made so as to provide means for identification of its operative conditions. Besides the experimental results, the paper also takes into account computational methods for the corresponding theoretical studies. In this way, a model proposal and its implementation into the well-known ATP software is included. Both the experimental and simulation results are compared for validation purposes.