Optimal Phase Arrangement of Distribution Feeders Using Immune Algorithm

In this paper, the immune algorithm (IA) is proposed to derive the rephasing strategy arrangement of laterals and distribution transformers to enhance three phase balancing of distribution systems. The multi-objective function is formulated by considering the unbalance of phasing currents, the customer service interruption cost and labor cost to perform the optimal rephasing strategy. To demonstrate the effectiveness of the proposed methodology to enhance three-phase balancing of distribution systems, a practical distribution feeder in Taipower with 523 customers is selected for computer simulation. By minimizing the objective function subjected to the operation constraints, the rephasing strategy has been derived by selecting the laterals and distribution transformers for phasing adjustment. The phase currents and neutral currents of test feeder before and after the execution of proposed rephasing strategy have been measured and collected by the SCADA system in Taipower. It is found that the neutral current of test feeder has been reduced to be less than the over neutral current limit by executing the rephasing of laterals and distribution transformers.