Three-Phase-Two-Wire Rural Distribution System Planning: Load Phase Distribution for Minimum Voltage Unbalance

The Three-Phase-Two-Wire (TPTW) system is an emerging technology designed to enhance electricity supply in rural areas. A prototype of this system was recently installed in Rio Grande do Sul, Brazil. A major challenge in TPTW is the inherent voltage unbalance. In conventional three-phase systems, loads are evenly distributed among the phases, but in TPTW, this leads to voltage unbalance. As a non-conventional system, TPTW requires a specialized method for load distribution. This paper proposes an optimization approach using Particle Swarm Optimization (PSO) to minimize voltage unbalance in rural TPTW networks. Additionally, a standardized phase distribution strategy is introduced to reduce computational effort. The methods were validated through statistical analysis, ensuring the representation of real-world system characteristics. The results show that the optimized method always provides the best solution, while the standardized method also provides satisfactory results, maintaining the voltage unbalance within the regulatory limits in most cases.