The next major milestone is approaching in the project to electrify the Great Western Mainline. In December 2018, Network Rail plans to energise the tracks as far as Cardiff Central, Royal Wootton Bassett and Newbury. Electrifying the route will make travel faster, quieter, greener and more reliable, with passengers enjoying more services and more space on board the Hitachi Class 800 trains.
ABB’s role in the project is to deliver the trackside substations and electrical distribution control system that will ensure a reliable power supply to the overhead catenary wires that will provide power to rolling stock. ABB is now putting the finishing touches to the substations that will serve the route.
One major advantage that ABB is bringing to the project is the capability to take advantage of the significant step forwards in electrical technology over recent years. State-of-the-art trackside switchgear and automation technologies have helped to de-risk the project, reducing the time required on site for construction, installation, testing and commissioning.
Working smarter not harder
Another important element of the work is that the protection and control scheme deployed by ABB has enabled Network Rail to reduce its project costs. This scheme is designed to detect and isolate faults before reconfiguring the network and returning power to healthy sections of track automatically within six seconds — without any intervention by a human operator.
Called the Rationalised Autotransformer Scheme (RATS), the protection and control arrangement is based on a philosophy developed by Network Rail. Its objective is to use the latest smart grid communication and control technology to reduce the number of high value circuit breakers on the route.
Ultra-fast communication for the control signals means that less costly load break switches can be used instead of circuit breakers in some instances. Load break switches are designed to control the flow of power in normal circumstances, but they are not able to handle the large currents that can develop under fault conditions.
This has enabled the RATS scheme to be arranged so that load break switches control the flow of power to individual sections of line but are protected from ever experiencing a fault current by circuit breakers.
Instead, ABB has implemented a protection, control and control system based on the IEC 61850 smart grid protocol to detect faults whenever they arise on the system. Remote Terminal Units (RTUs) at the trackside substations then relay the fault signal to open the circuit breaker and then communicating the status and raising an alarm at Network Rail’s control centre.
Award-winning innovation
On 13th September, the Rationalised Autotransformer System (RATS) was named as the innovation of the year at the National Rail Awards 2018. The judges were impressed with an estimated cost saving of around £1 million per 10 km, as well as improvement in the time taken to clear faults.
Speaking about the project, the award judges said: “We were blown away by the description of what this innovation has achieved. It appears to be a world first in the electricity industry. It represents a big step change in design and standards, offering numerous future benefits, including cost reduction, construction timescale reduction, less maintenance, more reliability and less damage through faults.”
Plug and play digital solution
ABB deployed the RATS scheme in the form of Auxiliary Equipment Enclosures (AEEs). These are containerised enclosures that house all the protection and control equipment for each substation, as well as communication equipment to link substations along the route.
There is a rule of thumb that estimates that issues identified during Factory Acceptance Testing (FAT) will cost one tenth of those that need to be rectified on-site. It also reduces risk of project slippage, as well as health and safety risk.
Therefore, factory assembling and testing the AEEs before delivery to site ready to plug and play has enabled ABB to ensure efficient project delivery.
Rigorous bench testing
An important element of creating the AEEs was the bench testing of the RATS scheme to guarantee that the sophisticated system would work effectively once delivered to site.
Engineers at ABB’s system verification facility in Stone, Staffordshire carried out extensive testing to simulate real- life conditions on the Intelligent Electronic Devices (IEDs) before installation in the AEEs. The team tested the IEDs for multiple substations at once to evaluate the performance of communication and decision-making inside each substation as well as between separate sites.
The testing team used eight Omicron test sets to inject currents and voltages to replicate conditions on the network, with Omicron’s RelaySimTest software co-ordinating the timing to inject currents and voltage simultaneously from all test sets.
State-of-the-art switchgear
Another priority for Network Rail is to enhance its environmental footprint. In response, ABB supplied switchgear in the form of SMOS Light (Structure Mounted Outdoor Switchgear Light).
The switching element in SMOS Light is provided by ABB’s well-established FSKII+ circuit breaker, which is the only vacuum-insulated trackside circuit breaker to be listed on Network Rail’s list of approved products. See page 28 for more information on SMOS Light.
This is a modular type of switchgear that integrates all the elements needed to isolate the supply to sections of overhead line or sectionalise individual parts of track. Multiple switchgear bays were installed at each of the traction substations along the line, along with AEEs and transformers.
Major milestones
- March 2014: ABB and project partner UK Power Networks Services were appointed for turnkey delivery of trackside substations
- February 2015: First substation energised
- June 2015: Trials of electric train operation
- December 2017: Electrification of line between Maidenhead and Didcot Parkway
- December 2018:planned electrification as far as Cardiff,Royal Wootton Bassett and Newbury
