  Unbalance issues in low-voltage distribution networks (LVDN) can be worsened
by increasing penetration of residential PV generation if unevenly distributed
among three phases. To address this issue, the phase-switching device (PSD)
provides a viable and efficient method by dynamically switching customers to
other phases. This paper further investigates how to optimize residential phase
connections by controlling PSDs efficiently. The optimization problem is
formulated as a mixed-integer non-convex programming (MINCP) problem
considering relevant operational requirements of an LVDN based on the exact
formulation of unbalanced three-phase optimal power flow (UTOPF). Unlike most
heuristic algorithms and the linearization techniques in our previous work,
this paper proposes to solve the MINCP problem via an iteration-based algorithm
after exact reformulations and reasonable approximations of some constraints.
The proposed method is tested in a real LVDN and compared with the approach of
Zhao et al. based on the well-known linear UTOPF formulation. Case studies
based on the European low-voltage test feeder demonstrate the proposed method's
efficiency in mitigating the network unbalance while ensuring network security
and flexibility to deal with more controllable resources.
