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Nexans has announced that its superconducting fault current limiters (sFCLs) have been installed to future-proof Birmingham’s electricity power grid to meet the city’s growing energy. This solution also defers or reduces the need for large investments to upgrade the networks or replace substations to keep pace with network changes. By James Hunt:
Western Power Distribution has integrated two superconducting fault current limiters (sFCL) from Nexans into Birmingham’s electrical power grid. Nexans designed and manufactured both 12kV sFCLs.
In what is now the company’s third UK sFCL project, Nexans delivered the first unit to the Chester Street substation in late 2015, and the second to Bourneville substation, nearby the famous Cadbury’s chocolate factory. Both sFCLs are now permanently integrated into the grid.
The need for change
This £17m project will, it is claimed, transform the grid in the city, reducing power cuts and carbon emissions, and these sFCLs are part of the FlexDGrid project. This is aimed at increasing the capacity of existing networks to facilitate the distribution of renewable energy in Birmingham.
As UK networks shift from large centralised generation to more distributed means, such as wind farms, the networks need to adapt to the changing load profile. Until now, the need for protection against high fault currents in the network required large expensive protective devices using many copper parts.
It was for this reason that Nexans developed sFLCs as part of its commitment to provide the most innovative and reliable solutions to future proof grids. These devices provide effective protection from the fault currents that constitute a growing problem in power grids. They can also help reduce the need for new substations.
By using sFCLs, therefore, networks can be operated at their optimum loading without risk of damage through faults. The technology also opens up new ways of designing distribution grids, such as with coupling busbars to maintain a reliable power supply during maintenance.
Since 2005, Nexans has successfully installed the technology at five other sites across the UK and Germany, including as part of the Ampacity project in Essen, Germany.
Addressing the world’s changing energy needs
Commented Frank Schmidt, Head of the Superconductivity Business Unit at Nexans: “We’re excited to have completed delivery of superconducting fault current limiters to Western Power Distribution for permanent integration into the grid.
“This further demonstrates,” he said, “Nexans’ ability as market leader in superconducting systems for power grids. The contract represents our commitment to continuing the deployment of state-of-the-art equipment to address the world’s ever changing energy needs.”
Jonathan Berry, Innovation and Low Carbon Networks Engineer at WPD, said: “Nexans’ proactive approach meant that following device testing we were able to successfully install and commission the sFCLs at Chester Street and Bournville substations. The devices are now on load and we’re waiting to see their performance under a real network fault situation.”
How sFCLs work…
The technology is based on the physical properties of the ceramic superconducting material used. In its normal operating state, the material acts as a near perfect electrical conductor without ohmic resistance, remaining invisible to the network and relying on the zero resistance of the superconductive material. It doesn’t, therefore, affect grid operations. A fault current, however, will transform the superconductor into a resistive material, increasing the resistance and reducing the fault current in a few milliseconds.
The change in the physical state of the material is so quick that it immediately limits the first peak of the short circuit current (the first peak is responsible for mechanical damage coming from the magnetic field created by the fault current).
The device works without any electronic trigger function, just using the physical phenomena of superconductivity. It is, therefore, automatic and wear free. When the fault clears, the sFCLs will go back to its original state, zero resistance.
The applications include busbar couplers between two neighbouring MV grids, and the protection of large industrial plants where the fault current can reach extremely high values.
For more information, go to: http://www.nexans.com