Hitachi testing ‘world’s most powerful’ subsea transformer for Ormen Lange compression system

Hitachi Energy has started testing what is said to be the world’s most powerful 24-MVA subsea transformer, which will be supplied to OneSubsea to power the compression system for the Shell Ormen Lange field in the Norwegian Sea.

As informed, the transformer is being tested in the Port of Vaasa in Finland and will enable the electrification of subsea equipment using renewable hydropower thus reducing energy consumption and carbon emissions.

The tests will involve submerging the 55-tonne subsea transformer into the harbour basin to monitor its thermal behaviour and pressure compensation system, as well as ensure its reliability in subsea conditions, Hitachi said.

According to the company, the transformers are a part of a large contract for the supply of two subsea OceaniQ transformers, two input transformers, two step-up transformers, and a common step-down distribution transformer.

Once tested the subsea transformers will be submerged off the Norwegian coast in waters to a depth of about 850 metres and will power the OneSubsea multiphase compression system for the Ormen Lange field in the Norwegian Sea.

The subsea transformers are due to be delivered by the end of 2022.

For this project, Hitachi collaborated with ABB which is supplying its INSUBSEA Long Step-out solution to deliver power to the OneSubsea compressors and has overall system responsibility for the power scope of the project.

The OneSubsea compression system will be powered and controlled from the Nyhamna onshore gas processing plant, which is 120 kilometres away from the subsea location. This is said to be a world record for transmitting variable frequency power from an onshore facility to equipment on the seabed.

The system will lower back pressure on the reservoir, helping increase recovery and extend the life of the field.

“We are delighted to be collaborating with ABB and OneSubsea on this important project. A subsea transformer is an advanced technology due to its ability to operate in waters at a depth of up to 3,000 m and in extremely demanding conditions, including high pressure, corrosion, subzero temperatures, and strong underwater currents”, said Bruno Melles, head of the Transformer Business at Hitachi Energy.

Melles added that the company’s OceaniQ subsea transformer technology is also suited for the connection of floating offshore wind farms to the grid.

Ormen Lange Phase 3 is a fully subsea-to-shore processing system fed by hydroelectric power from the Norwegian grid. It is known as one of the lowest carbon-intensive and most energy-efficient recovery improvement projects in the industry.

The deep-water project off the Norwegian coast will produce natural gas from deep in the Norwegian Sea and bring it onshore to a refinery in Nyhamna. The plant supplies around 20% of the UK’s total gas consumption.

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