Analysis of Neutral Wire Current according to Grounding Method of Overhead Ground Wire and Neutral Wire under Load Unbalance

Abstract

At present, 22.9kV Y-connected three-phase four-wire multi-grounded distribution networks are adopted in distribution networks in South Korea. If such distribution networks are not balanced, a high unbalanced neutral wire current may flow into the neutral wire. This unbalanced current is mainly caused by a load imbalance and may have a detrimental influence on communication wires, electrical equipment, etc. Therefore, it is necessary to reduce the neutral wire current. In this paper, an analysis of the neutral wire current according to different grounding methods of the overhead ground wire (OHGW) and neutral wire at two-step-type poles was conducted using the Electromagnetic Transients Program. By comparing the effects of the grounding method (i.e., common or separate) under load unbalance conditions, we can determine an effective grounding method for reducing the neutral wire current.