A Look into Steady State and Transient Performance of Power Lines Integrating Single Wire Earth Return Circuits

In order to get a descriptive picture of the effect of ground properties on a distribution line, a comparison between a two-phase line with neutral return and a single wire earth return (SWER) line is carried out. Both, steady state and transient performance are assessed. The impact of relevant parameters such as line length, grounding resistance at the customer site and soil resistivity along the SWER line is integrated in the analysis. Results reveal important aspects that can assist in deciding acceptable operating limits of the SWER system, particularly regarding voltage drop, increased losses due to the normally small size of single phase conductors, faults, etc. All simulations were conducted using PSCAD V4.

I. Introduction

SWER systems are used in some parts of the world where electricity has to be delivered to extended areas in rural communities with low population densities, notably in Brazil, Australia, New Zealand, Africa, India, Latin America and Canada [1], [2]. Loads are typically light but the extension of the single wire circuits can often reach 200, 300 and even 400 km. Also, due to the small size of the conductors voltage drop and increased losses are important issues for utilities. Frequently, lines span across soils of varying resistivity and getting low grounding resistance values at customer sites often require of improved grounding methods.