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

TL;DR

This paper introduces a hybrid multi-terminal soft open point with feeder selector switches, enhancing distribution system flexibility and capacity, especially for integrating low carbon technologies.

Contribution

It proposes a novel Hybrid MT-SOP design with AC/DC converters and feeder switches, and demonstrates its improved efficiency and capacity over existing solutions.

Findings

Feasible power transfers increased by up to 50% with asymmetric converter sizing.

System loss reduction improved by 13% compared to equal-sized MT-SOP.

Converter utilization increased by over one third.

Abstract

Distribution systems will require new cost-effective solutions to provide network capacity and increased flexibility to accommodate Low Carbon Technologies. To address this need, we propose the Hybrid Multi-Terminal Soft Open Point (Hybrid MT-SOP) to efficiently provide distribution system interconnection capacity. Each leg of the Hybrid MT-SOP has an AC/DC converter connected in series with a bank of AC switches (Feeder Selector Switches) to allow the converter to connect to any of the feeders at a node. Asymmetric converter sizing is shown to increase feasible power transfers by up to 50% in the three-terminal case, whilst a conic mixed-integer program is formulated to optimally select the device configuration and power transfers. A case study shows the Hybrid MT-SOP increasing utilization of the converters by more than one third, with a 13% increase in system loss reduction as compared to an equally-sized MT-SOP.