24 hours to dock, load and sail. 12 hours to get into position and install. 24 hours to commission. The third milestone in A2SEA’s installation formula, we asked turbine manufacturers how realistic the 24-hour commissioning target is for them.

As part of an effort to simplify and communicate the key milestones in the offshore wind turbine installation process of the future, A2SEA’s four-step 24/12/24/12 formula has generated a lot of interest and discussion in the offshore wind industry. At present, the commissioning time for offshore wind turbines can take up to a few weeks, which is a long time for valuable offshore assets that could be generating power and income to stand idle – and it’s expensive too. But this is hopefully going to change.

Future perfect?

An ambitious target, the 24-hour commissioning period extends from when the turbine is fully installed to when power is first fed to the grid. According to Kaj Lindvig, Senior Advisor at A2SEA, who has followed the development of new turbines over the years, “Turbine manufacturers have been working on lowering the commissioning period for a long time and it’s an important element of the new turbine developments.”

But is this time frame realistic? “When asked directly, the turbine manufacturers believe it will be possible in a few years. Turbines based on the new direct drive technology are more or less fully commissioned when they’re installed. But first, the installation time has to be reduced from several days to a few days, which should be possible with the first 6 to 8MW turbines. The situation is a little different for some of the smaller, gear-driven turbines, as the transformer and part of the frequency converter are in the bottom of the tower, and they have to be connected to the cables and switch gear, and then tested. This can take several days, but that can be reduced as well.”

The advantage with the new type of turbines is that they can be tested onshore. “The manufacturers can perform 90 to 95 percent of the testing in port, which will make it a lot easier to achieve this figure,” says Kaj. But, as he points out, it’s a learning curve. “They need to get the first series of large turbines installed first.”

A fresh approach

For Peter Holmgaard, Offshore Project Execution Director at Alstom, the 24-hour commissioning time is realistic. “Alstom is a relative newcomer to offshore wind turbine manufacturing, so that means we can do things a little differently. For us, the big driver is how much pre-commissioning we can do at our factories. We’re working on a plug-and-play cabling solution for our Haliade 150 6MW direct drive turbines that we can test under full load when our new factories are completed.”

Driving progress

With its first Haliade 150 installed and the second almost ready for testing in the North Sea, Alstom is confident it can meet the 24-hour commissioning target. And with 240 turbines scheduled for delivery for French projects in 2016, Alstom will be able to see its plug-and-play cabling solution in action.

An ambitious target? Definitely. But with the support and determination of an equally ambitious industry, a 24-hour commissioning window should become a reality within the next few years.

 

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