Successive MISOCP Algorithm for Islanded Distribution Networks with Soft Open Points

An optimal operation scheme is of great significance in islanded distribution networks to restore critical loads and has recently attracted considerable attention. In this paper, an optimal power flow (OPF) model for islanded distribution networks equipped with soft open points (SOPs) is proposed. Unlike in the grid-connected mode, the adequacy of local power generation in distribution networks is critical for islanded systems. The proposed approach utilizes the power output of local distributed generations (DGs) and the benefits of reactive power compensation provided by SOPs to allow maximum loadability. To exploit the available resources, an optimal secondary droop control strategy is introduced for the islanded distribution networks, thereby minimizing load shedding. The formulated OPF problem is essentially a mixed-integer nonlinear programming (MINLP) model. To guarantee the computation efficiency and accuracy. A successive mixed-integer second-order cone programming (S-MISOCP) algorithm is proposed for handling the nonlinear islanded power flow formulations. Two case studies, incorporating a modified IEEE 33-bus system and IEEE 123-bus system, are performed to test the effectiveness of the proposed approach.