A Three-Phase Unbalanced Line Model with Grounded Neutrals through a Resistance

Distribution Analysis power-flow and short-circuit studies typically model overhead and underground lines assuming that the neutrals are solidly grounded. That assumption has come under question since grounded wye lines will not actually have zero resistance between the neutral conduction and ground. Without a solid ground there will be a voltage between the neutral and ground. In order to determine the voltage under typical operating conditions a model for the grounded wye lines must be developed. The purpose of this paper is to present the data for a simple three-phase overhead line that is grounded at regular intervals through a resistance. Companion papers will use this data to develop models that can be used in power-flow and short-circuit studies. The final result will be a "standard" line model that will include the grounded neutrals through a resistance.