Planning of unbalanced radial distribution systems using differential evolution algorithm

This paper presents a planning approach for unbalanced radial distribution systems using differential evolution algorithm (DE) so as to determine the optimal phase balancing and conductor sizes. The objective functions used in the planning are minimization of: (1) total complex power unbalance, (2) total power loss, (3) average voltage drop, (4) voltage unbalance factor, and (5) total neutral current. The optimization is done under the constraints of minimum and maximum voltage limits for each bus voltage and thermal limit of each line. A three phase forward–backward sweep load flow algorithm is developed and used for the determination of these objective functions. The effectiveness of the proposed planning algorithm is corroborated on 19-bus and IEEE 25-bus unbalanced radial distribution systems. The results show that significant improvements in power loss and voltage drop with simultaneous optimization for phase balancing and conductor sizes. The performance of DE is found to be better and consistent as compared to some other meta-heuristic algorithms studied here.