The Gunfleet Sands 3 Demonstration Project involved A2SEA’s SEA INSTALLER transporting and installing two Siemens 6MW turbines at the DONG Energy-owned and operated wind farm. Located off the coast of East Anglia, the project gave all three companies the opportunity to bring their latest technology to the table, and put it to the test.

With Round 3 offshore wind farms scheduled to get underway in 2016, wind farm suppliers are moving into the final testing phases of their latest equipment and technology. In order to achieve the target capacity of 20GW by 2020, offshore wind farm owners and operators need to understand the challenges involved in installing and operating these high capacity wind turbines in deeper waters.

Performance testing

A UK first for DONG Energy and Siemens Wind Power, the Gunfleet Sands 3 project will allow the companies to gain valuable knowledge and experience about how the new direct drive 6MW turbines perform in an offshore environment. And for A2SEA, it was an ideal opportunity to put the SEA INSTALLER through her paces.

Following installation, the turbines will be monitored for about a year. The monitoring activities include structural load measurements, analysis of the direct drive generator, vibration measurements, and grid compliance, as well as provide a valuable insight into the offshore installation process. According to David Summers, EPC Director at DONG Energy, “DONG Energy is committed to reducing the cost of energy through the development of new technologies. The test site will help us clarify potential design risks for the new turbine, perform early mitigation, improve DONG Energy’s knowledge of design parameters and O&M procedures, and contribute to capital expenditure decisions.”

For Siemens Wind Power, the test site will also be a great opportunity to improve processes and prove the technology. Siemens has installed two test turbines onshore, but these two are the first installed offshore. Half a year ago, Siemens announced that it had made a deal with DONG Energy to supply a total of 300 turbines in a frame agreement. For Siemens, it is essential to show and test the technology for the client before the first serial produced 6MW turbines are supplied to DONG Energy projects in 2014.

From load out to commissioning

The SEA INSTALL ER was awaiting load out of the last components at the Port of Esbjerg when we spoke to Søren Grøn, Project Manager at A2SEA, in early January. Søren was very pleased with the SEA INSTALLER’s performance, but the big test was to come when her four legs are lowered into the seabed. “That will be the main challenge. The water at the site is about 17 to 21 metres, which isn’t particularly deep, but the seabed is soft and we’re anticipating a penetration of 10 to 12 metres. This makes the project more difficult and time consuming, and the crew will have to ensure the vessel’s footing is safe and secure.”

After the turbines are installed, there’s the challenge of retracting the legs. “The legs are often more difficult to get out than in, which makes things a little more tricky. For the crew, this means more controls and steps that need to be taken in order to ensure a safe retraction – but we’re prepared,” added Søren.

After we spoke to Søren, the result was a successful installation. The first positioning of the vessel was accurate to an incredible three centimetres. And after the legs with their large spud cans penetrated many meters into the seabed, they were efficiently and quickly retracted from the seabed with the help of the purpose-built water injection system.

 

 

 

Like this post? Subscribe now and get notified about new content!