GE’s 4.1-113 prototype large offshore wind turbine, nicknamed ‘Big Glenn’ and located in Gothenburg harbour, Sweden, has passed its initial trial run. Beginning on 29 February, the trial lasted 200 hours. This is GE’s first direct-drive offshore WTG and it came through the reliability run on its first attempt with 99.05 percent availability. Wind speed varied during the run from zero to rated wind, resulting in a capacity factor of 35.3 percent.
“The variation in wind speed gives the team confidence that the turbine performs reliably under all wind conditions,” says Vincent Schellings, offshore product manager for GE Energy. “Now we will begin validating the design and obtain initial results before summer. Our initial focus will be on the power curve and loads validation as evidence that our simulations meet the measurements of the two performance characteristics that matter most to our customers.”
The 4.1-113 is intended specifically for the offshore environment, with reliability and availability as the primary design drivers. With fewer moving parts, the direct-drive technology provides a simple, reliable design with built-in redundancy and partial operation for major components, all focused on keeping turbines operating reliably at sea. GE believes that direct-drive technology eliminates costly gearbox parts and lowers operating expenses. The 4.1-113 blade design has been optimised for highest energy capture at sites suitable for monopile applications and is based on the five years operating history of GE’s installed fleet of 3.5 MW land based turbines.
