Prominent cable maker Nexans reports that it has completed a successful test of the world’s first HVDC superconducting power transmission cable.
The voltage tests were carried out at the Nexans’ high voltage laboratory in Hanover, Germany, shown left. A prototype HTS cable together with a termination was subjected to a series of tests according to CIGRE specification. They included testing at 360 kV, representing 1.8 times the 200 kV operating voltage, for several hours. In addition the system was successfully subjected to superimposed overvoltages.
This result constitutes an important step in demonstrating the capability of underground HVDC HTS cables to transfer bulk power at the levels required by proposed supergrid projects such as the Tres Amigas renewable energy market hub in the US. The next step is to adapt this HTS cable system to the very high currents (up to 12500 A) required to carry several GW of power.
“This self-funded programme constitutes the first stage in the development of an HTS cable system suitable for supergrid projects such as Tres Amigas.”
The HVDC HTS cable is based on a similar configuration to the 138 kV alternating current (AC) HTS cable currently operating in Long Island in the US (an installation designed and implemented by Nexans, and commissioned in 2008). The key design challenges have concerned the termination (connecting the cable to the electrical network) which is completely different from that used in AC systems.
Other steps still to be taken involve the development of suitable joints to enable the installation of long lengths of HTS cable as well as for repairs.
A possible first test would be the Tres Amigas project in the USA which will create the first renewable energy market hub in the US. Its purpose is to enable faster adoption of renewable energy and increase the reliability of the US grid. For the first time, the project in Clovis, New Mexico would unite the three US power grids - the Eastern Interconnection, the Western Interconnection and the Texas Interconnection.
The three grids would be connected by ‘superconducting electricity pipelines’ comprising HVDC power cables and VSC (voltage source converter) AC/DC power converters. The Tres Amigas renewable energy market hub would be a 9.6 km triangular electricity circuit capable of transferring and balancing many gigawatts of renewable power among the three grids with nearly 100% efficiency.
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