Project
DC railway and metro systems, that are supplied by unidirectional substations, demonstrate a significant waste of energy due to their inability to fully recover the energy produced by electric braking.
New supply solutions like Bidirectional substations and/or storage systems are expected to significantly improve energy efficiency.
e-TRENY will support enhanced energy efficiency in DC railway systems, via new traceable methods for:
- on-site measurement of the efficiency of substation power transformers
- measurement of the efficiency increase achieved by the adoption of new supply solutions.
Background
In railway/metro/tram systems supplied by unidirectional DC substations, the energy regenerated by the traction units must be consumed within the DC railway traction grid. Any extra-energy generated by electric braking is dissipated by the braking rheostat and thus wasted. From the energy analysis performed on experimental data provided by the EMPIR project 16ENG04 MyRailS, (i.e. data that was recorded during the monitoring of different railway traction-units in commercial service), it was concluded that a value ranging from a few percent up to 50 % of the available regenerative energy is dissipated and thus wasted. Moreover, estimates show that up to 1 GWh per year, about the annual consumption of 365 families, can be wasted in one single commuter line of 120 km.
To address this issue of energy waste, new supply configurations that allow the flow of excess power from DC to AC (reversible substations) or/and that adopt stationary storage systems, have been proposed and are currently being installed. However, there is a strong need for standardised methodology for the assessment of the energy efficiency performance of these new installations. In particular methods that safeguard both the designer, the supplier, the installer and the railway infrastructure manager.
Background
In railway/metro/tram systems supplied by unidirectional DC substations, the energy regenerated by the traction units must be consumed within the DC railway traction grid. Any extra-energy generated by electric braking is dissipated by the braking rheostat and thus wasted. From the energy analysis performed on experimental data provided by the EMPIR project 16ENG04 MyRailS, (i.e. data that was recorded during the monitoring of different railway traction-units in commercial service), it was concluded that a value ranging from a few percent up to 50 % of the available regenerative energy is dissipated and thus wasted. Moreover, estimates show that up to 1 GWh per year, about the annual consumption of 365 families, can be wasted in one single commuter line of 120 km.
To address this issue of energy waste, new supply configurations that allow the flow of excess power from DC to AC (reversible substations) or/and that adopt stationary storage systems, have been proposed and are currently being installed. However, there is a strong need for standardised methodology for the assessment of the energy efficiency performance of these new installations. In particular methods that safeguard both the designer, the supplier, the installer and the railway infrastructure manager.
Needs
- Sustainability of DC transportation system
- Methodologies for the performances analysis of non-conventional AC/DC substations CLC Tc9X need
- Power transformer losses under actual grid and nonlinear load conditions
- High power converter systems (AC/DC, AC/AC, DC/DC) accurate On-site efficiency
- New traceability for DC dynamic and AC distorted signals
- To determine the system efficiency improvement by new ESSs.
Needs
- Sustainability of DC transportation system
- Methodologies for the performances analysis of non-conventional AC/DC substations CLC Tc9X need
- Power transformer losses under actual grid and nonlinear load conditions
- High power converter systems (AC/DC, AC/AC, DC/DC) accurate On-site efficiency
- New traceability for DC dynamic and AC distorted signals
- To determine the system efficiency improvement by new ESSs.
Normative needs
The technical report CENELEC/TR 50646 that defines the specifications for reversible DC substations, states the currently unaddressed standardisation needs for the effective characterisation of reversible DC substations. In particular, the report lists a series of key performance indexes that should be proved by the reversible DC substation provider that are currently not standardised: i) energy saving, ii) performance in terms of harmonic compensation on AC and DC side, iii) performance in terms of reactive power compensation, and iv) determination of efficiency at different levels of the converter group and for different operation modes (traction, regeneration).
CENELEC TC14 has also called for on-site determination of power transformer losses under actual operating conditions, which requires accurate and traceable measurements.