Periodic Reporting for period 2 - FUNDRES (FUTURE UNIFIED DC RAILWAY ELECTRIFICATION SYSTEM)
Reporting period: 2020-12-01 to 2021-11-30
The challenge for the railway sector regarding energy is to increase the capacity while improving the energy consumption and limiting the environmental impacts, and to decrease the investment and exploitation costs, while maintaining safety and service quality. It makes it necessary to rethink railway power supply under future requests, reflecting the status of different systems.
The project FUNDRES presents a deep thinking and related work to define the future of railway, based on new unified Future UNified Dc Railway Electrification System based on 9 kvDC, able to integrate the existing lines during transition period. In the coming years, MVDC power grids will contribute to the deployment of renewable energies and the electrification of transport systems. Compared to classical AC electricity distribution networks, they are generally more energy efficient and facilitate the interconnection of sources, storage elements and loads. In 2018, a new 9 kV DC railway electrification system was presented as an opportunity for railway sector. The ambitions of FUNDRES were to bring substantial improvements in the energy technology area and station for the future unified system based on 9 kV DC. The consortium composed by LAPLACE, EPFL, POLIMI and UIC proposed to develop several scenarios, validated by experimental demonstration at the laboratory level (TRL4) and digital twin which offers the possibility to predict the behaviour of the proposed unified electrical system based on 9kV DC.
The project outputs will be used to deliver new integrated technology demonstrators and scientific progress for the project IN2STEMPO, and more largely for Shift2Rail, which will be implemented in the railway network.
The project FUNDRES allowed to demonstrate:
- The possibility to restore braking energy to the public grid. To study several scenarios, a Real Time Hardware In the Loop (RT-HIL) system has been developed both for MMC and railway system. The RT-HIL system was implemented on a real-time simulator equipment (RT-Box). In parallel with this work, two prototypes of MMC (5 kV / 250 kVA - 48 cells) were built to set-up a test platform to realize an experimental demonstration (currently ongoing) at the real voltage level of the future DC railway electrification system
- The feasibility of the integration of renewable sources into a railway traction system, taking into account the various power flows due to the railroad traffic and the natural variability of the Renewable Energy Sources. This demonstration was made the set up of a Digital Twin (DT) of the future 9 kV DC power system.
- Promising results in terms of energy efficiency have been obtained by carrying out experimental tests of one elementary module of a Solid State Transformer (SST). To do so, an electrical model of a three-wire DC power supply, including SSTs, was proposed to prepare for a transition between 1.5 kV and 9 kV electrification systems. A full 3D design of a 9 kV/1.5 kV SST in a container configuration has been completed.
The project FUNDRES presents a deep thinking and related work to define the future of railway, based on new unified Future UNified Dc Railway Electrification System based on 9 kvDC, able to integrate the existing lines during transition period. In the coming years, MVDC power grids will contribute to the deployment of renewable energies and the electrification of transport systems. Compared to classical AC electricity distribution networks, they are generally more energy efficient and facilitate the interconnection of sources, storage elements and loads. In 2018, a new 9 kV DC railway electrification system was presented as an opportunity for railway sector. The ambitions of FUNDRES were to bring substantial improvements in the energy technology area and station for the future unified system based on 9 kV DC. The consortium composed by LAPLACE, EPFL, POLIMI and UIC proposed to develop several scenarios, validated by experimental demonstration at the laboratory level (TRL4) and digital twin which offers the possibility to predict the behaviour of the proposed unified electrical system based on 9kV DC.
The project outputs will be used to deliver new integrated technology demonstrators and scientific progress for the project IN2STEMPO, and more largely for Shift2Rail, which will be implemented in the railway network.
The project FUNDRES allowed to demonstrate:
- The possibility to restore braking energy to the public grid. To study several scenarios, a Real Time Hardware In the Loop (RT-HIL) system has been developed both for MMC and railway system. The RT-HIL system was implemented on a real-time simulator equipment (RT-Box). In parallel with this work, two prototypes of MMC (5 kV / 250 kVA - 48 cells) were built to set-up a test platform to realize an experimental demonstration (currently ongoing) at the real voltage level of the future DC railway electrification system
- The feasibility of the integration of renewable sources into a railway traction system, taking into account the various power flows due to the railroad traffic and the natural variability of the Renewable Energy Sources. This demonstration was made the set up of a Digital Twin (DT) of the future 9 kV DC power system.
- Promising results in terms of energy efficiency have been obtained by carrying out experimental tests of one elementary module of a Solid State Transformer (SST). To do so, an electrical model of a three-wire DC power supply, including SSTs, was proposed to prepare for a transition between 1.5 kV and 9 kV electrification systems. A full 3D design of a 9 kV/1.5 kV SST in a container configuration has been completed.
At the end of reporting period n°2, all workpackages of the project have been completed.
The Workpackage 2, dedicated to Grid interaction Railway power supply and public grid, has been led by EPFL which achieved:
- The development of the RT-HIL based Digital Twin of MMC
- The development of the modelling framework for the distributed real-time models, considering that for the first-time, we have used many RT-Box units to realize the HIL system.
- The commissioning and the experimental verification of the MMC control software on the HIL, providing foundation for the further studies.
For Workpackage 3, led by POLIMI and dealing with the connection with renewable resources, storage systems and charging infrastructure, the main achievements are:
- The analysis of voltage drops with/without renewables
- The power flow analysis with/without regenerative braking energy
- The analysis of the regenerative’ s percentage braking energy sent back to the grid
- The study impacts on the proposed railway system and AC mains
- The evaluation of the impact of the use of energy coming from solar panel or wind turbines on Power/voltage/current profile of substations
- The power ratings of substations extracted by power/time output graphs
- The provision of ancillary services to the mains and the analysis of particular transient events
- The sizing of energy storage systems in relation to the railway traffic
- The peak shaving analysis of railway systems
Regarding Workpackage 4 led by LAPLACE, which aims at providing the model of the future Solid State Transformer through a 9KVDC network, the main achievements are:
- A prototype of an elementary building block (isolated DC/DC converter) of a SST unit was developed and successfully tested.
- A complete electrical model of SST unit was developed.
- The Mechanical Design of the elementary building block in vertical arrangement has been considered most suitable for an integration in container.
- 3D Design and recommendation for the integration of SST units into the railway infrastructure were specified in the deliverable D4.1.
The Workpackage 5 has been led by UIC which ensured the dissemination of the project results during all its duration.
After the completion of the project the outcomes will be exploited by the partners by pursuing the project’s researches (by reusing the digital twin for instance) and by publishing and presenting the project’s results during incoming relevant events.
The Workpackage 2, dedicated to Grid interaction Railway power supply and public grid, has been led by EPFL which achieved:
- The development of the RT-HIL based Digital Twin of MMC
- The development of the modelling framework for the distributed real-time models, considering that for the first-time, we have used many RT-Box units to realize the HIL system.
- The commissioning and the experimental verification of the MMC control software on the HIL, providing foundation for the further studies.
For Workpackage 3, led by POLIMI and dealing with the connection with renewable resources, storage systems and charging infrastructure, the main achievements are:
- The analysis of voltage drops with/without renewables
- The power flow analysis with/without regenerative braking energy
- The analysis of the regenerative’ s percentage braking energy sent back to the grid
- The study impacts on the proposed railway system and AC mains
- The evaluation of the impact of the use of energy coming from solar panel or wind turbines on Power/voltage/current profile of substations
- The power ratings of substations extracted by power/time output graphs
- The provision of ancillary services to the mains and the analysis of particular transient events
- The sizing of energy storage systems in relation to the railway traffic
- The peak shaving analysis of railway systems
Regarding Workpackage 4 led by LAPLACE, which aims at providing the model of the future Solid State Transformer through a 9KVDC network, the main achievements are:
- A prototype of an elementary building block (isolated DC/DC converter) of a SST unit was developed and successfully tested.
- A complete electrical model of SST unit was developed.
- The Mechanical Design of the elementary building block in vertical arrangement has been considered most suitable for an integration in container.
- 3D Design and recommendation for the integration of SST units into the railway infrastructure were specified in the deliverable D4.1.
The Workpackage 5 has been led by UIC which ensured the dissemination of the project results during all its duration.
After the completion of the project the outcomes will be exploited by the partners by pursuing the project’s researches (by reusing the digital twin for instance) and by publishing and presenting the project’s results during incoming relevant events.
The ambitious targets it sets were for the improvement of rail sector energy efficiency, the reductions in GHG emissions and a more sustainable balance between transport modes. Over the past two decades, the European rail industry has provided considerably more energy efficient products to its customers. Improvements concerned mainly the rolling stock which was equipped with regenerative braking or energy storage technologies. Nevertheless, further gains in energy efficiency are necessary to reduce the energy consumption and carbon intensity of the railway system.
The project FUNDRES presented a deep thinking based on a Future UNified Dc Railway Electrification System, based on 9 kV DC, able to integrate renewable sources and storage devices. During the project, the feasibility of this new railway electrification system has been demonstrated by digital twins and some experimental tests at laboratory scale.
Even if electric power suppliers increasingly consider developing DC networks, the introduction of a new MVDC electrification system in the railway world will not be easy. We must consider this over a horizon of several decades. It takes time to convince.
Several obstacles remain to be overcome and we can notably mention:
- The development of traction chains capable of operating under 9kV DC.
- The development of circuit breakers for interrupting short-circuits currents under 9 kV DC.
- The writing of normative texts to define the characteristics of this new system and the management rules of energy flows.
The project FUNDRES presented a deep thinking based on a Future UNified Dc Railway Electrification System, based on 9 kV DC, able to integrate renewable sources and storage devices. During the project, the feasibility of this new railway electrification system has been demonstrated by digital twins and some experimental tests at laboratory scale.
Even if electric power suppliers increasingly consider developing DC networks, the introduction of a new MVDC electrification system in the railway world will not be easy. We must consider this over a horizon of several decades. It takes time to convince.
Several obstacles remain to be overcome and we can notably mention:
- The development of traction chains capable of operating under 9kV DC.
- The development of circuit breakers for interrupting short-circuits currents under 9 kV DC.
- The writing of normative texts to define the characteristics of this new system and the management rules of energy flows.