A global optimum flow pattern for feeder reconfiguration to minimize power losses of unbalanced distribution systems

The loss minimization has been an important optimization problem in distribution systems because of the economic incentives. The state-of-the-art feeder reconfiguration for minimizing unbalanced distribution systems' losses cannot prove the optimality of solutions mathematically due to the non-convexity of the problem. This paper proposes a global optimal flow pattern of feeder reconfiguration to provide a best start point and convergence direction for search strategies. The global optimality and the uniqueness of the global optimal flow pattern are proved. Therefore, the loss of the global optimal flow pattern is the lower bound of the feeder reconfiguration for loss minimization. Two global optimal flow pattern-based search strategies are developed to find the global or near optimal solutions. The performance of the proposed algorithms is validated with three test systems for different application scenarios. Test results demonstrate that the efficiency of the search strategies is greatly improved by the global optimal flow pattern and the optimality of solutions can be verified.