16ENG04 MyRailS Metrology for smart energy management in electric railway systems

• Forschungsstelle: METAS
• Projektnummer: F-5213.30083

Schlüsselwörter (Englisch)

Railway, energy efficiency, energy metering, power quality assessment, eco-driving, reversible substation, energy braking, dynamic measurement conditions, harsh environment, calibration system

Kurzbeschreibung (Englisch)

Considering the overall annual energy consumption of the European railway system, about 36.5 TWh, and the ambitious target of reducing CO2 railway transport emissions by 50 % by 2030, it is clear that an efficient use of energy in the railway system is required. To this end, accurate and reliable knowledge of the energy absorbed/exchanged between the train and the railway grid, that takes into consideration the harsh on-board measurement conditions, is essential.

To establish a single European railway area, the European Commission requires, by 2019, that energy billings shall be computed on the actual energy consumed [1],[2]. All trains shall be equipped with an energy measurement function (EMF), whose measurement accuracy shall be assessed and periodically re-verified, as required by EN 50463-2 [3]. To assess the metrological reliability of the EMF under operating conditions, calibration set-ups and procedures which go beyond the well-known procedures developed for pure sinusoidal or continuous regimes are required.
Efficient use of the infrastructure, encouraged by the European Union, requires new constraints for the railway energy supply systems. In this scenario, accurate knowledge of the real-time power quality is a valuable tool to foster the efficiency of the whole railway system by “awarding” the good power quality delivered and absorbed.
New installations of reversible substations in DC railway systems, able to transfer the excess energy produced during braking to the upstream AC network, can improve energy saving. A reliable procedure for the estimation and measurement of the potential energy saved by reversible substations (RSSs) is a valuable tool in the cost-benefit evaluation. Eco-driving (driving a train as efficiently as possible by maintaining a speed profile designed to reduce economic and environmental costs) is a further energy saving technique that needs accurate on-board energy measurements for the definition of the best eco-driving strategy. Currently, uncertainties of tens of percent on the absorbed energy measurements make this information unusable for assessing the efficiency of eco-driving strategies.

This is a joint research project carried out in the framework of the European Metrology Programme for Innovation and Research (EMPIR) (see:http://www.euramet.org/research-innovation/empir/). The EMPIR initiative is co-funded by the European Unions's Horizon 2020 research and innovation programme and the participating states. METAS is one of the project partners in the Project.

Projektziele (Englisch)

The overall objective of the project is to develop the metrological framework and measurement infrastructure that underpin the adoption of energy efficient technologies in European railway systems.
The specific objectives of the project are:

1. To develop a metrological framework for calibration (comprising laboratory and on-board train calibration / measurement set-ups and robust data processing algorithms) to enable high accuracy energy and power quality (PQ) measurements under highly dynamic electrical conditions approaching the uncertainty limits stated in the EN 50463-2:2013-05 with a frequency range from a few hertz up to 5 kHz for AC systems and up to 3 kHz for DC systems. The uncertainty targets for laboratory calibrations are 0.5 % and 0.1 % respectively for AC and DC systems, and 0.4 % for on-board calibration of DC systems. All major European supply systems (25 kV/50 Hz, 15 kV/16.7 Hz, 3 kV/DC, 1.5 kV/DC, 750 V/DC and 600 V/DC) will be considered.
2. To develop a wide-area power quality monitoring architecture. This will include diagnostic studies, system models, numerical simulations, power quality indices definition, measurement system implementation, time-synchronisation, wide-area communication, centralised data collection for quantifying the efficient use of the railway infrastructure and for on-board identification of the PQ events affecting the power exchanged between the supply system and the rolling stock (including high-capacity converter device effects, intermittent sliding-contact arcing and resonance effect).
3. To set up combined measurement-simulation tools to analyse the existing energy-use profiles of DC rolling-stock supplied with traditional unidirectional substations and to quantify the impact of the installation of new reversible substations in terms of energy saving but also in terms of power quality with a target uncertainty of 1 %.
4. To develop accurate measurement systems and procedures for evaluating the energy saving provided by an eco-driving strategy. To reduce the uncertainty of the on-board energy measurement to 1 % to enable assessment of the reliability of an eco-driving forecasting model and to identify and test good practices in on-site estimation of eco-driving benefit.
5. To facilitate the take up of the technology and measurement infrastructure developed in the project by the measurement supply chain (accredited laboratories), standard developing organisations (EN) and end users (train manufacturers, railway companies).

Abstract (Englisch)

The project aims to develop the metrological infrastructure for accurate measurement of energy exchange and for reliable system monitoring, which underpins the implementation of an energy efficient management of the European DC and AC railway and DC subway system. The project also focuses on the characterisation of the railway subsystem as a producer-consumer, with a view to its integration in a wide smart grid, as well as on the assessment of eco-driving performances.

Umsetzung und Anwendungen (Englisch)

A new power base (measuring station 213.11) has already been used within the EURAMET.EM-K5. The previous power base was unsuitable for frequencies below 47 Hz and above 63 Hz - especially power at DC is in great demand in the moment in connection with charging stations for electric vehicles. The unique feature of METAS is currently CMCs without a lower limit for the frequency, i.e. also for f → 0.

The extension of the measuring station 213.21 High current to include high-frequency components has already been used for four customer orders. 
Even though the measuring station 213.22 high voltage is still limited to the fundamental due to the delayed delivery of the high voltage amplifier, the new measuring system is already in use. This has simplified the equipment to be maintained. Various customer services could only be offered thanks to the additional functionality already achieved without the amplifier.

The overhauled measuring stations 213.23 and 213.24 are also regularly used for customer services and the return of references from METAS and the verification laboratories. 

Through the project the involved METAS expert has joined the IEC TC 8 MT 62888. Here, IEC 62888-2 will be revised shortly. This standard adopts essential parts of EN 50463-2, according to which we have already tested electricity meters for railway applications. The aim of the activities in IEC TC 8 MT 62888 is, on the one hand, to ensure that we can offer tests according to the revised standard as quickly as possible, to influence new requirements if they should be difficult for us to test practically, and, on the other hand, to establish customer contacts.