Siemens will manufacture 66 2.3MW turbines, with a 108-metre diameter for the Grand Wind project in Grant County, north Oklahoma on the border with Kansas.
Delivery and installation is expected to begin this month with project completion due in spring 2016. Siemens will also service the turbines under a long-term deal, says the turbine supplier.
The nacelles will be manufactured at Siemens' facility in Kansas, and the 53-metre blades produced in Iowa.
In April, Siemens won a contract from developer Apex to supply the same 2.3MW turbine to the 300MW Kay Wind project in neighbouring Kay county.
"With this second order in one year, Apex Clean Energy continues our successful collaboration," said Thomas Richterich, CEO of Siemens onshore wind division.