Speed-e von REN: Foto: REN
During the eMove360° Europe 2022, 6th International Trade Fair for Mobility 4.0 electric-connected-autonomous (05 to 07 October), the finalists of one of the world’s most important awards for New Mobility were announced on the evening of 05 October in Berlin. The expert jury of the eMove360° Award for Electric Mobility & Autonomous Driving had nominated the most innovative and promising submissions for mobility. In the Charging & Energy category, Speed-E by REN convinced the jury.
The increasing introduction of electric vehicles (EV) requires the development of a widespread charging infrastructure. The application of classic solutions is unlikely to be sufficient to ensure the required pace of transition. To meet this challenge, REN has developed SPEED-E, a new grid interconnection solution capable of supplying high-power electric vehicle charging stations directly from the extra-high voltage (HV) grid.
The transport sector is moving towards massive electrification, setting additional challenging targets for the energy sector and the transport industry. Considering that the introduction of electric vehicles is highly dependent on reducing “range anxiety”, charging infrastructure should desirably be deployed faster than the introduction of electric vehicles to enable a successful and smooth transition. Furthermore, the development of this infrastructure requires a robust response from the distribution networks to provide the necessary power availability. Indeed, the growing demand for electricity to charge electric vehicles is creating pressure on the distribution network, which will eventually lead to grid reinforcement requirements. Consequently, the development of charging infrastructure is already often hampered by distribution grid connection problems, which not only relate to additional grid connection costs due to grid reinforcement requirements, but also to extended lead times for the implementation of such grid reinforcements. This problem becomes particularly relevant in specific cases with high power requirements, such as large charging stations and in cases where ultra-fast charging technology is used.
SPEED-E overcomes these problems by bypassing the distribution grid and providing a direct connection to the existing extra-high voltage transmission grid. This is possible because the nominal power associated with electric vehicle charging, although significant to the distribution networks, can be negligible from a transmission network perspective. For example, the total power of 25 superfast 150 kW chargers is 3 750 kW. This represents only about 1% of the total transmission capacity of a single transmission line in Portugal, and the same principle can be extended to any other country/energy system.
The SPEED-E solution is synergistic within a national electricity system by creating an additional use for the existing transmission network and positions itself as a complement to the mainstream charging infrastructure in urban centres.
SPEED-E directly positions the transmission grids as a relevant player in the energy transition and supports the decarbonisation of the transport sector in a competitive way by using the existing grid. Transmission grids would otherwise only play an indirect role in facilitating the electrification of the transport sector.
This innovative solution was developed internally by REN and consists of a small substation connected to an existing extra-high voltage transmission line with a special connection scheme, which allows for increased operational flexibility and reliability. The substation uses power voltage transformers to convert very high voltages directly to low voltages, bypassing the conventional multiple step-down approach that involves different substations to convert from: 1) very high voltages to high voltages; 2) high voltage to medium voltage; and finally 3) medium voltage to low voltage.
The innovation associated with this substation architecture is based on the following main components:
… which minimises the impact on the reliability of the overhead line and mitigates impacts on grid operations.
… which ensures maximum continuity of power supply to the EV charging station, even if maintenance or other interventions in the VHV line are required.
…a circuit breaker to disconnect the substation from the mains, consisting of an earthing switch;
…power voltage transformers – key technology consisting of VHV/NS transformers.
REN developed this concept using only commercially available equipment and carried out a proof-of-concept project in Portugal, connected to an existing 220 kV transmission line that has been in operation since 2018. In parallel, REN successfully applied for a European patent. The European patent was granted in April 2021 (EP3616294) and is currently valid in 32 European countries. There are also ongoing patent proceedings in the USA and Canada.
The key differentiators of this solution compared to traditional distribution grid power solutions include (I) “virtually unlimited” power available at any location, (II) sustainability of the solution, (III) modularity and scalability, and (IV) quality of service :
(I) Virtually “limitless” power – In terms of power retrieval from the grid, when considering the extra-high voltage transmission grid, the power demand for electromobility pur Posen apply as a remainder. For example, if an electric vehicle charging station operator decides to install 80 fast chargers (50 kW) in a single location, the power required for simultaneous use is about 1% of the average 220 kV overhead line rated power in the Portuguese grid;
(II) Sustainability – SPEED-E represents a sustainable solution in that it leads to a new use of the existing transmission grids available across countries without requiring grid reinforcements due to the new electricity demand from a new use of electricity, i.e. electromobility. This approach complements existing available solutions and is particularly valuable outside urban centres where rural distribution networks may struggle to cope with the fast charging power required during commuting and provide nationwide coverage for future electric vehicle deployment;
(III) Modularity and scalability – These features provide the ability to manage investment risk by adjusting installed capacity to meet growing demand. The initial charging station can be provided with an installed capacity adapted to the current demand (e.g. current size of the electric vehicle fleet), which can later be expanded according to the growth of demand from the electric vehicle side or the growing attractiveness of the charging location without requiring a change in the connection to the VHV line, resulting in a long-lasting solution. In addition, the demand for “ultra-fast chargers” is expected to increase in the long term, leading to higher electricity demand. With this in mind, SPEED-E enables the replacement of the original chargers as well as adaptations to the transformers without changing either the line connection or the location of the charging station;
(IV) Quality of service – In terms of continuity of supply, this solution provides the quality of supply associated with the national transmission network directly to the end user. In particular, the equivalent interruption time (EIT) of an extra-high voltage network (transmission) is significantly lower compared to a high, medium or low voltage network (distribution), as distribution networks are typically more exposed and consequently more influenced by external factors such as extreme events like storms, strong winds, heavy snowfalls or forest fires. This can be particularly relevant in cases where the end-user is a company whose daily operations depend heavily (or absolutely) on the functioning of vehicles (e.g. public transport companies, logistics companies, etc.). www.ren.pt
