The design, installation and commissioning of offshore wind farms are facing several challenges for the inter array grid. The continuously increasing power ratings of the individual wind turbines leads to increasing operating voltages (Um), from 36 kV to 72.5 kV for the inter array cables to reduce operating currents and therefore thermal losses. As these cables are designed as high voltage and not as medium voltage cables, the after-installation testing should be done by resonant test systems (RTS) as defined in IEC 63026:2019 and CIGRE TB 841.
HIGHVOLT, as a market leader, has a track record of more than 260 RTS systems in operation worldwide and developed a completely new RTS system for offshore operation. As offshore conditions are quite different to conventional onshore onsite tests, the test system must be adapted to the specific requirements for transportation and operation offshore.
Discussing these requirements with all stakeholders, like platform operators and test service providers, a basic conformity with offshore standards was defined, compliant with DNVGL-ST-E 273. Additional stakeholder discussions brought up the continuously increasing importance of the specific operating procedures during transport, erection, and operation of the high voltage test system on the offshore substation (OSS).