Transmission
for sustainability
DEMO 5

Superconductor cables power up for DC grids

Objective

Prototype scale validation of the technical feasibility of integrating DC superconducting cable links within an AC meshed network.

Nature of work and planned activities

Within the next 10 years, superconducting power cables could offer significant power transmission solutions for densely populated, high load areas. These future transmission power systems will need to transfer from 2 to 20 GW of power over distances of a few hundreds of km from remote wind farms to the final distribution centres. In this application, long superconducting cables could carry very high currents, from 5 –10  kA, without resistive losses, achieving very high power levels in combination with high voltages up to 400 kV. At the same time, in the dense urban business districts of large cities, the purchase of easements and construction costs for standard cables is becoming prohibitive.


Superconducting cables could serve two other applications:
 

  • Medium voltage feeds for load centres in dense urban areas where the grid is often saturated, and existing infrastructure is ageing. Superconducting technology can bring a considerable amount of power to new locations where the construction of additional transmission / distribution substations, with major transformer assets, is not feasible.
     
  • Improvement of grid power transmission by connecting two existing substations: in dense urban environments, many substations have reached their capacity limits and require redundant transformer capacity to ensure reliability. Superconductor cables can tie existing stations together, avoiding costly transformer upgrades and construction costs.


Any industrial superconducting material (including the newer MgB2 in this project) must be kept at very low temperature, while the basic wire needs significant performance improvements to enable wide commercialization. Currently, cable manufacturers use wire with a relatively low current capacity, requiring more material to achieve the desired nominal current. Higher capacity wire increases current density and decreases the amount of material required. Market commercialization is also highly dependent upon cost reductions for cable components like the superconducting wire, cryostat and cooling stations.
 

While several demonstrations have been launched for AC networks, this project is investigating the suitability of MgB2 technology as a component of a DC grid by operating a prototype with a very high power transmission level. It uses a monopole cable system operating between 5 to 10 kA / 200-320 kV for a transmitted power of 1 to 3.2 GW and operating in helium (He).

Planned activities

  • Design and construction of a prototype electrical feeder system
     
  • Manufacture of MgB2 wires and the cable conductor
     
  • Manufacture of HVDC electrical cable insulation
     
  • Cooling system (cryogenic) design for He gas
     
  • Developing procedures for connection of the superconducting link to a DC grid
     
  • Investigating the nominal and transient behaviour of a MgB2 component embedded in a grid
     
  • Investigating  behaviour of the grid with an operating superconducting cable

Benefits

Short superconductor links, a few hundred metres in length could offer solutions for network operators facing challenges ranging from substation footprint availability or lack of available rights of way, to high load underground connections between urban substations. 

Partners involved

Nexans (Leader), CERN, Columbus, ESPCI, IASS, KIT, RSE, RTE, TU Dresden, UPM. 

 

 

Superconductor cable design