Siemens will deliver 47 turbines to the project in the Irish Sea, with the blades being manufactured at the company's new Green Port Hull facility currently being constructed in north-east England.
The company unveiled the new 7MW turbine at the EWEA Offshore 2015 conference in Copenhagen this week. It is an enhanced version of its SWT-6.0-154 turbine.
Siemens Offshore CEO Michael Hannibal described the turbine as having "the same generator, we've just put in some other magnets". Changes were also made to the transformer.
Siemens has a tradition of slowly uprating its turbines. The 3.2MW and 4MW were originally 3MW and 3.6MW respectively.
Also today, ABB was awarded the contract by Dong to supply the project's export cable. The $130 million contract will see ABB supply over 180 kilometres of cables connecting the projects two substations and carry power to the UK grid.
Last month, Dong named MHI-Vestas as the preferred turbine supplier for the first 330MW phase of the project with its V164-8MW.
Dong has split the project into two phases because the site has two distinct areas with differing features, according to a Dong spokesperson.
"This will allow us to optimise the site and create two separate phases of the project. This, with the flexibility afforded to us through the phased contract for difference (CfD) agreements, enables us to exploit the opportunity to develop the project using different technology," the spokesperson added.
The Walney Extension was handed a final investment decision-enabling CfD subsidy by the UK government in April 2014 and was approved in November. A final investment decision by Dong is still pending.