This paper presents a new step size optimization factor to be used for solving unbalanced three-phase distribution current injection power flow. This optimization factor improves the performance of the iterative process namely at higher loading level and R/X ratio. In addition, this paper also proposes to extend the concept of this optimization factor to calculate the multiple unbalanced three-phase power flow solutions. In order to verify the effectiveness of the proposed methodologies, a practical Brazilian distribution test system and an ill-conditioned power network have been used.