A body of the European Union
A body of the European Union
Rail infrastructure and rolling stock requires a complex electrical network – one that can transform energy from public power supply networks and then distribute this energy along the track to the rail vehicles.
Within today’s railway infrastructure, system energy consumption is usually measured at the substations. This consumption tends to be averaged over a defined period, which doesn’t allow for an exact energy analysis.
An increasing demand for rail-based journeys means an increased demand for power availability. Combine this with a general shift to making railways even more sustainable, and it is easy to see why rail must address its energy supply and consumption challenge. Doing so starts with the ability to properly measure and manage energy use.
By leaning into innovation, the Shift2Rail Joint Undertaking has delivered two Technology Demonstrators (TDs) that do exactly that:
Smart Power Supply Demonstrator: A smart railway power grid in an interconnected and communicated system.
Smart Metering for Railway Distributed Energy Resource Management System Demonstrator (‘Smart Metering’): A fine mapping of energy flows within the entire railway system as a basis for any energy management strategy.
Whether based on alternating current (AC) or direct current (DC), a railway traction power supply system delivers the required energy to the trains. However, as the rail network shifts towards a smart railway power grid, the railway traction power grid will require important smart functionalities to improve energy management, both in its supply to rolling stock and in its interactions with the supply grid. It also can integrate new sources of electricity, such as wind turbines and solar panels, and to feed new customers such as stations and electric vehicle charging points.
Here, the Smart Power Supply TD defined and demonstrated several solutions for optimising traction power supply systems for electrified railways:
The Smart Power Supply TD’s work includes installing and operating a demonstrator for the smart control of rail power supply within a 16.7Hz railway environment. The demonstrator was designed in detail and subjected to extensive lab testing. These included factory acceptance tests to demonstrate full functionality, along with system integration tests to validate its correct operation in conjunction with primary substation equipment.
Various applications were also developed, tested and analysed in a simulation environment, with a specific focus on voltage stability, double sided and interconnected feeding arrangements, improved power quality and reduced power losses. Various negative aspects, such as harmonic overvoltage, resonance instability and low frequency oscillations, were also explored.
The consortium further proposed using power electronic converters as a means of electrifying railways with a higher voltage of 9kV. The converters are based on modular multilevel converters (MMC). Digital twins of the converters were created, enabling their testing and validation prior to deployment. The MMC prototype was also tested in a laboratory environment.
Furthermore, the TD looked at the possibility of integrating renewable energy sources into a new 9kV DC railway system. It also used modelling and simulation to investigate whether a 1.5kV DC line could be reinforced with the addition of a parallel 9kV DC feeder based on solid state transformers located trackside.
These findings demonstrate not only how smart power systems can be implemented, but how they can provide enhanced control and protection capabilities for railway power systems. Furthermore, the solutions offer a clear path forward towards boosting the performance and capacity of existing lines without the need for extravagant investment costs.
As such, the application of these solutions will benefit both future and existing electrification schemes.
In rail, smart metering has the potential to provide the real-time information needed to optimise energy consumption. For example, a train-tracking system based on GNSS (Global Navigation Satellite Systems) can provide accurate, dependable and timely information to the controller. Likewise, a train’s speed and dynamic status can be measured using an accelerometer, a common sensor found in most smartphones.
Information gathered from different sensors can be combined into a comprehensive database, which serves as the basis for building user-customised applications to evaluate the situation and, ultimately, enhance energy management.
However, implementing such a smart metering system first requires a detailed mapping of a railway system’s energy consumption. The knowledge of load curves at the rolling stock, traction substation, and auxiliary services levels will enable global system load prediction, peak shaving and energy cost optimisation. It will also highlight where the most effective actions can be implemented to save energy.
Here, the consortium’s work focused on the technical activities required to prepare sites for smart metering. This included developing novel, data-driven ICT (Information and Communications Technology) solutions that railway systems can use to monitor, analyse and utilise energy and energy asset related data. It then demonstrated these solutions via three use case:
Amongst the solutions developed are various energy metering services. When connected to multiple sensors via a heterogeneous telecommunications platform to an open data management (ODM) platform, these services can facilitate data collection, analysis and subsequent action.
In addition, the consortium of experts built a communication system to interconnect many devices, which can be located either on-board a vehicle or trackside, with an ODM platform. The ODM platform can monitor and analyse the collected data, either in real time or later.
The TD also developed applications designed to translate the collected data into concrete actions for improving the energy efficiency of railway infrastructure. These applications can be used to, for example, predict energy demand on an infrastructure, estimate a railway system’s energy consumption, and predict abnormal patterns in a railway traction system.
As the TD implemented its smart metering solutions into three use cases, the functional specifications and architecture for the smart metering systems were clearly defined for each use case, including detailed descriptions of the equipment installed and the methodology used to collect the data.
The smart metering data was captured, processed and analysed on the newly built ODM platform.
For each use case, various user applications were developed to show how the collected smart metering data can be used to inform energy efficiency strategies in general and, more specifically, to improve energy efficiency; conduct preventive maintenance, fault detection and mapping; and to understand energy flows.
The feasibility of smart metering systems has been successfully demonstrated and validated across all relevant technology areas – sensors and communications, ODM and user applications. Key findings include:
The data collected and analysed by the TD demonstrates real benefits that can be derived from smart metering. While the use of non-intrusive smart metering in railways is still at a very early stage, this work highlights the importance of ensuring that all future rail infrastructure components and subsystems come with built-in smart metering capabilities.
Together, the combination of the non-intrusive smart metering techniques and the centralised data collection capabilities represent a step change in energy management and make a clear case for smart metering in rail. With a broad implementation of smart metering systems, energy efficiency potential can be systematically exploited, system performance can be optimised, maintenance effort and costs can be reduced and the overall economic and environmental performance of railways increased.
As such, it is not unreasonable to expect that the detailed mapping of energy consumption, done using smart metering technology, will become a standard feature in railways systems.
While the potential for smart metering and smart power supply solutions are significant in their own right, they can be particularly powerful when used in synergy with each other.
Not only do smart power supply solutions improve control and protection functionality for railway power supply systems, they also transmit energy data to smart metering platforms. This data then feeds user-centric applications, which in turn can directly enhance energy management.
Add this up and what you have is a powerful tool to better understand – and improve – railway power supply and energy consumption.