Optimizing Phase Allocation in Unbalanced Power Distribution Networks using a Linearized DistFlow Formulation

TL;DR

This paper introduces a MILP-based method using linearized DistFlow equations to optimize phase allocation in unbalanced power distribution networks, improving balance and reducing issues caused by increased unbalanced device integration.

Contribution

It presents a novel MILP approach with phase consistency constraints for phase allocation, advancing beyond heuristic methods in unbalanced network management.

Findings

Effectively improves network balance in benchmark tests

Reduces protection device triggers and losses

Ensures phase configuration consistency downstream

Abstract

Power distribution networks, especially in North America, are often unbalanced but are designed to keep unbalance levels within the limits specified by IEEE, IEC, and NEMA standards. However, rapid integration of unbalanced devices, such as electric vehicle (EV) chargers and single-phase solar plants, can exacerbate these imbalances. This increase can trigger protection devices, increase losses, and potentially damage devices. To address this issue, phase swapping (or phase allocation) has been proposed. Existing approaches predominantly rely on heuristic methods. In this work, we develop a mixed integer linear programming (MILP) approach for phase allocation. Our approach uses linearized DistFlow equations to represent the distribution network and incorporates a phase consistency constraint, enforced with binary variables, to ensure that downstream phase configurations align with upstream configurations. We validate the proposed approach on multiple benchmark test cases and demonstrate that it effectively improves network balance, as quantified by various metrics.