  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.

Systems and Control;Systems and Control