High temperature superconducting (HTS) cables have been under development around the world since the discovery of HTS materials in 1986. Rapid advances in the technology have taken place since 1999 with more than six in-grid projects in utility networks around the world.
HTS cables utilize superconducting materials [link to What is Superconductivity] in place of copper or aluminum conductors in conventional cables to carry electric current. What is the advantage and why is this area of technology development important? These are both very good questions with the following answers:
(1) Superconductors have virtually zero electrical resistance and therefore can transmit electrical power at higher efficiencies than conventional copper or aluminum conductors.
(2) These materials also have substantially higher power density which translates to much higher power throughput for a given cross-section.
Why Develop HTS Cables:
The two advantages described above lead to application benefits for electric power networks, especially in congested urban areas. HTS superconducting cables offer solutions for utilities facing challenges that include:
- substation footprint availability
- lack of available rights of way
- high load connections between substations
The high power density of the materials allow HTS cables to operate at steady state ratings of up to 4,000 Amps – far exceeding what may be achieved with conventional underground cables with copper conductors. To achieve this, the HTS materials must be maintained at extremely cold temperatures to enable the superconducting characteristics. The cables operate at approximately -200° C (-320° F).