Three-Phase-Two-Wire Rural Distribution Network: Influence of Design Characteristics on Voltage Unbalance

Power distribution in remote areas with low density load is usually performed with Single Wire Earth Return (SWER) systems. These systems have been shown to be insufficient to meet not only the growing demand but also three-phase loads. The Three-Phase-Two-Wire (TPTW) system is a non-conventional low-cost alternative system for repowering the SWER, as both of them use the ground as conductor. The TPTW system is inherently unbalanced and may have greater voltage drops than a conventional three-phase system. This paper proposes a method to decrease voltage unbalance by choosing the correct spacing between of TPTW System overhead conductors. Additionally, the method eliminates the need for reactive series compensation and reduces working time and installation costs. TPTW System performance was evaluated for different conditions and designs such as cable type, spacing, length and passive compensation. The results show that optimal spacing can be reached among cables, and viable supply can be offered for distant loads with relatively low voltage unbalance.