Metrology support for enhanced energy efficiency in DC transportation systems

Transportation generates almost one quarter of Europe’s greenhouse gas emissions (GHG). Road vehicles are a major contributor and increasing the use of ‘cleaner’ electric DC railway and metro systems can deliver significant energy savings.

However, energy wastage can occur when trains brake - equivalent to around 1 GWh per year for a single commuter line. To reduce this, reversible DC substations’ (RSS) can be installed containing power converters and storage systems that harvest breaking energy.

European standards, such as EN 50646, provide recommended measurements for determining the performance of RSS components, such as substation converters and traction transformers, but uncertainty on RSS energy benefits has limited uptake of this technology. Standardisation groups have expressed a need for improved measurements covering the operation of new instrumentation and systems under real-world conditions.

Building upon the EMPIR project MyRailS, a traceable measurement infrastructure will be developed to measure on-site losses of energy conversion systems in metros and tramways during commercial service.

New power measurement facilities will allow the first ever determination of losses for high-power, high-efficiency (> 97%) converters under actual grid conditions, providing insight to the transport industry into the actual efficiency of RSS in the presence of grid harmonics and other disturbances. Along with new on-site calibration techniques, the knowledge gained will be incorporated into a good practice guide and shared with standard developing organisations for incorporation into relevant standards.

Increasing the confidence of station designers and electric transport operators in RSS will encourage its uptake, improve the energy efficiency of public transport, and help Europe reduce GHG that drive climate change.