Phase swapping for distribution system using Tabu Search

In power distribution systems, feeders frequently exhibit some imbalance between phases. Feeder imbalance occurs when the currents (I-a, I-b and I-c) of a three-phase system do not have the same magnitude at any load point along the feeder, because some phases are more heavily loaded than others. A state of imbalance in power systems may cause excessive voltage drops, unnecessary energy losses, and increased risk of feeder overload. It may also affect system power quality and electricity price. In order to correct this state of disproportion, phase balancing can be utilized. One solution to phase balancing is to swap single-phase loads from one phase to another to make the currents identical at each load point on the feeder. This technique is called phase swapping. Balancing loads in a distribution system can enhance utilities competitiveness by improving reliability and by reducing costs. The determination of the optimal swapping scheme is a non-linear problem. The efficiency of using Tabu Search to solve this non-linear phase balancing problem is demonstrated. Tabu Search is a heuristic method that enhances the performance of a basic local search technique by using a memory structure. The Tabu Search algorithm to find the optimal phase swapping scheme with the minimal cost was developed using a model from an unbalanced feeder from a typical Local Distribution Company (LDC).