New phase‐changing soft open point and impacts on optimising unbalanced power distribution networks

Abstract

Three-phase unbalanced conditions in distribution networks are conventionally caused by load imbalance, asymmetrical fault conditions of transformers and impedances of three phases. The uneven integration of single-phase distributed generation (DG) worsens the imbalance situation. These unbalanced conditions result in financial losses, inefficient utilisation of assets and security risks to the network infrastructure. In this study, a phase-changing soft open point (PC-SOP) is proposed as a new way of connecting soft open points (SOPs) to balance the power flows among three phases by controlling active power and reactive power. Then an operational strategy based on PC-SOPs is presented for three-phase four-wire unbalanced systems. By optimising the regulation of SOPs, optimal energy storage systems dispatch and DG curtailment, the proposed strategy can reduce power losses and three-phase imbalance. Second-order cone programming (SOCP) relaxation is utilised to convert the original non-convex and non-linear model into an SOCP model which can be solved efficiently by commercial solvers. Case studies are conducted on a modified IEEE 34-node three-phase four-wire system and the IEEE 123node test feeder to verify the effectiveness, efficiency and scalability of the proposed PC-SOP concept and its operational strategy.MAX maximum active and maximum reactive powers of DER at node i at time t * conjugate transpose

Design and Operation of Hybrid Multi-Terminal Soft Open Points using Feeder Selector Switches for Flexible Distribution System Interconnection

“…For the purposes of this work, converter losses are assumed to be linear with real power transfer (as considered in previous works on SOPs, e.g., [8], [13]). For the ith converter, we calculate converter losses P Loss, Cnvtr [i] as…”

“…An alternative approach to maximize converter utilization is via the reconfiguration of the power electronics themselves as part of Hybrid AC/DC systems, given the low cost of legacy AC technologies in comparison to their DC counterparts. In [8], the authors present a phase-changing SOP, whereby individual legs of a three-phase SOP are permuted (e.g., phase A connected to phase B) to reduce unbalance and improve network performance. The advantages of reconfigurable, parallel AC and DC lines are shown in [9].…”

Assessment of Jiangsu Regional Logistics Space Nonequilibrium Situation by Boosting and Bagging Algorithms

“…e logistics parking lots in Nanjing, Wuxi, Changzhou, and Wuxi in southern Jiangsu are developed, with Wuxi being the most developed, and there is logistics development in southern, central, and northern Jiangsu. e regional and unbalanced characteristics of it are obvious [7]. In recent years, the Jiangsu region has gradually shown problems of unbalanced economic development, resources, development location, logistics layout, development scale, and development level.…”

Optimal Operation of Soft Open Points-Based Energy Storage in Active Distribution Networks by Considering the Battery Lifetime

“…Ref. (Lou et al, 2020;Wang et al, 2020) further reduces the voltage unbalance in the unbalanced distribution network by controlling the three-phase power of SOPs. In (Chen et al, 2020;Ding et al, 2020), the SOP was used to enhance the service restoration ability of a distribution network.…”