Smart soft open point to synergically improve the energy efficiencies of the interconnected electrical railways with the low voltage grids

This paper presents a novel smart soft open point (sSOP) that interconnects railway electrification system to the local low voltage (LV) distribution grid to provide additional flexibility and controllability for both networks. The proposed sSOP builds on the concept of soft open points, adding an energy storage system and embedding a rail and grid (R + G) energy management system to enable the energy transfer between the two networks at different average power levels. The smartness of the proposed soft open point is realised in the integration of an energy storage system to act as an energy buffer between these two networks of different dynamics. The paper demonstrates that the proposed sSOP improves the braking efficiency of trains and increase the local use of renewable energy through employing an integrated simulation platform between a railway and smart grid simulators that takes into account the trains' timetables as well as the daily variation of the grid loads and renewable energy generation. The results show that an appropriate design and control of the sSOP enables the recuperation of most of the braking energy available from the railway and that energy is enough to mainly supply the local power distribution grid, thereby effectively implementing the concept of smart grids.