Analysis of a neutral grounding method for a three-phase four-wire 11.4 kV distribution system

In selection of the neutral grounding method in a three-phase four-wire 11.4 kV distribution system, it is necessary to take into consideration low voltage rise and induced voltage on telecommunication line in case of ground fault. In this paper, we perform EMTP/ATP simulation to select the optimal neutral grounding method and neutral grounding resistance with consideration to above mentioned conditions. The accuracy of the modeling procedure and simulation result is confirmed through verification test performed on test distribution line. As a result, we found (1) that the 11.4 kV distribution system should be associated with a resistance single grounding method; and (2) that the neutral grounding resistance should be above 20 Ω.