Exactness of OPF Relaxation on Three-Phase Radial Networks With Delta Connections

Simulations have shown that while semi-definite relaxations of AC optimal power flow (AC-OPF) on three-phase radial networks with only wye connections tend to be exact, the presence delta seem render them inexact. This article shows such inexactness originates from non-uniqueness relaxation solutions and numerical errors amplified by non-uniqueness. finding motivates two algorithms recover exact solution AC-OPF in unbalanced distribution featuring both connections. In simulations using IEEE 13, 37 123-bus systems, proposed provide up precision.