An Investigation of the Fundamental-Frequency Impedance of a Single-Phase Distribution Lateral

Fundamental-frequency impedance measurements conducted on a single-phase distribution feeder suggest that conventional methods of calculating line-impedance can lead to gross errors. These errors are shown to be due to lack of adequate modeling of the current division between earth and neutral as determined by neutral grounding. Models that include the effects of self-and mutual-impedances, pole-ground resistances, and endpoint impedances are presented and the results are compared with field test results. It is shown how Carson's equations can be correctly used in evaluating some of the model parameters. Simulation studies of the effects of pole-ground resistances on line impedance are presented. The use of probabilistic simulation in computing the statistics of impedance parameters, when pole-ground resistances are not accurately known, is also illustrated. Extensions of the approach to higher frequencies and to three-phase circuits are indicated.