The European LIGHTWIND project has completed its first test campaign for a new modular drivetrain architecture designed for offshore wind turbines above 15 MW and is now preparing for a second phase of testing.
The LIGHTWIND consortium comprises eight European companies and institutions: TNO in the Netherlands; IWES Fraunhofer in Germany; DIS/Creadis in Denmark; HCMR in Greece; MarinRes in Norway; and Euro-Funding, X1Wind and OptiGen in Spain.
The project is developing the OptiGen drivetrain concept, which replaces conventional large main bearings with a wheel-and-rail system positioned close to the generator air gap.
According to the project partners, the new drivetrain architecture addresses some of the challenges associated with increasing turbine power ratings, including larger structural dimensions and loads, heavier components, and the complexity and cost of maintaining high-capacity offshore wind turbines.
The wheel-and-rail configuration is also designed to simplify maintenance, according to LIGHTWIND partners, with components monitored and replaced within the turbine, without dismantling the entire nacelle and transporting it back to an assembly facility.
The first test campaign was based on a preliminary design using the IEA Wind 15 MW reference turbine. The project team identified the most critical components, particularly in relation to fatigue, and analysed the operating conditions and loads acting on the wheels and rails, as well as suitable materials.
A test rig was then developed to reproduce equivalent operating conditions on an accelerated basis and assess the durability of the system.
The mechanical system's dynamic behaviour was also tested using a hexapod, the Beat 1.1 developed by IDOM and located at Fraunhofer IWES facilities in Hamburg. The system was used to evaluate the drivetrain architecture under demanding operating conditions.
The results from the first campaign were positive, according to the project partners. The technical team is now implementing improvements and adjustments based on the first test phase before continuing with testing.
The activities are expected to bring the technology to Technology Readiness Level (TRL) 4, representing validation of the concept in a relevant environment and bringing it closer to potential commercial applications.
LIGHTWIND partners said they would also design a 22 MW version of the OptiGen system as part of the same project, based on IEA Wind Task 55, and assess whether the architecture could be scaled up to 30 MW.