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Solar firm to develop novel electronics for rail renewables

Image credit: Riding Sunbeams

Solar energy company Riding Sunbeams has won funding to develop power electronics technology that will enable it to feed renewable electricity directly into railway overhead wires.

The 'Daybreak' project is one of 25 to be awarded a share of a £9.4m government-backed fund to bring new technology to the railways and comes almost a year after the same team successfully demonstrated a direct connection between solar panels and the direct current (DC) third-rail traction system in Aldershot (pictured above).

Most electrified railway routes in Britain and around the world use AC overhead lines to power trains, but the technology needed to provide low-cost power conversion from renewables to AC rail traction systems does not yet exist.

The Daybreak demonstrator will repurpose existing technology already being used on UK rail networks for other purposes to create a new device that will provide the required power conversion. Alex Byford, chief technology officer at Riding Sunbeams, told E&T that the plan is to use existing technology as far as possible in order to reduce development time and costs, and because power electronics equipment that is already certified for railway use can cope with the heavy-duty cycles required.

Riding Sunbeams has formed a consortium with Network Rail; Angel Trains; Turbo Power Systems; the Birmingham Centre for Railway Research and Education, and Ricardo Energy & Environment to deliver the project.

The £400,000 grant from the Department for Transport and InnovateUK’s 'First Of A Kind 2020' programme will enable the team to procure the required equipment and modify it over the next nine months. Riding Sunbeams will then install a solar array coupled with lineside storage at Quinton Rail Technology Centre at Long Marston to power a locomotive directly with clean, green electricity for the first time.

Byford explained: “We are intending to create a new power-conversion device, which will convert the DC output of the solar array and the battery storage device to single-phase AC, as this is what the railway power supply requires. Our new device will use a mixture of DC/DC converters, to maximise the power output of solar panels and for the lithium-ion batteries, and an AC/DC bi-directional power electronic device to convert the DC power output to single-phase AC.

“Working in conjunction with Angel Trains, we have sourced an AC/DC bi-directional power electronic device which forms part of a traction converter, as is standard on an electric train powered by 25kV 50Hz overhead wires. We plan to re-use this device and a 25kV/LV transformer from a train, and also re-purpose some DC-DC converters which are common in the renewables industry, with some new software algorithms that we will develop.”

At the Quinton test facility, the solar array and containerised battery energy-storage units will be connected to the new power electronics conversion device, which will in turn be connected through a gantry to the overhead wires. “The power demand for a single locomotive (without carriages) should be entirely powered by our solar and storage systems,” Byford said.

The demonstration will provide a case for connecting to existing railway lines and also electrification of existing diesel lines with direct wire storage and renewables, he continued. “The main aim, however, is to prove that we can directly power both new and existing AC railways with direct-wire renewables with technology that is already at a high technology readiness level, so that we can progress with development of these sites in both the UK and abroad.

“Once we have completed our demonstrator project, our next step will be to finalise the design and begin the product approval and safety methodology requirements for use on the operational railway.

In particular, Riding Sunbeams hopes its technology will be able to play a part in delivering 70MW of direct-wire renewable generation to help power the soon-to-be-electrified Core Valley Lines in South Wales through a mixture of solar, wind and energy storage.

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