Shielding effect of multi-grounded neutral wire in the distribution system

The voltage induced by the power line on the nearby conductors, like telephone lines and pipelines, is investigated in this paper. The relationship between the phase currents and the neutral current plays an important role in reducing the induced voltage. Firstly, the impact of the MGN (multi-grounded neutral) configurations on the induced voltage is analyzed. It is found that the MGN-I (Islanded MGN) is the most practical configuration to reduce the induced voltage. Then a new method to calculate the neutral current for MGN-I is proposed. Based on the proposed method, a series of charts for neutral wire selections are given to facilitate the field engineers select the proper neutral wire. Finally, the validation of the proposed method is verified by the results obtained from EMTP-based multiphase harmonic load flow (MHLF) program. Copyright (C) 2010 John Wiley & Sons, Ltd.