Nexans and SuperGrid Institute have completed a transient overvoltage test (TOV) on a 525 kV DC cable system in accordance with new high-voltage direct current (HVDC) recommendations.

Using SuperGrid Institute‘s High Voltage testing facility, the DC cable system, produced and installed by Nexans, passed several sequences of damaged oscillating voltage tests at both 350 Hz and 6 kHz.

Martin Henriksen, department director of High Voltage Cable Systems at the SuperGrid Institute, added: “The validation of new damped over voltage test circuits is an important milestone for SuperGrid Institute’s high voltage laboratory. Located in the Lyon area (France), the laboratory is now ready to support European DC cable system manufacturers in the qualification of 525kV DC cable systems through extended type test programs, as required by TSOs.”

Nexans described the completion of the tests as a new milestone for the development of a resilient interconnected European grid and the integration of renewable energy.

Bjorn Sanden, technical director of High Voltage Techno Center at Nexans, said: “The completion of this test demonstrates and confirms the robustness and high reliability of Nexans HVDC cable systems even under transient events at the highest voltage levels.”

According to the company, HVDC cables are expected to play a major role in the infrastructure necessary for renewable energy integration. Multi-terminal topologies, mixed cable overhead line systems, and hybrid AC&DC grids will progressively reinforce the single point-to-point HVDC links currently being built, increasing the reliability requirements for HVDC cable system.

The French firm pointed out that HVDC systems might be subject to system-specific transient overvoltage (TOV) during disrupting events such as a fault in a converter station or a failure to ground the cable itself.

In 2022, several cable producers such as Prysmian, Sumitomo Electric Industries and South Korean LS Cable & System reported they had completed tests for their 525 kV HVDC cables.

Source – by Edin Neimarlija