2014 Wind Turbine Gearbox Damage Distribution based on the NREL Gearbox Reliability Database

Despite the improvements in wind turbine gearbox design and manufacturing practices, the wind industry is still challenged by premature wind turbine gearbox failures. To help address this industry-wide challenge, a consortium called the Gearbox Reliability Collaborative (GRC) was launched by the U.S. Department of Energy's (DOE's) National Renewable Energy Laboratory (NREL) in 2007. It brings together the parties involved in the wind turbine gearbox supply chain to investigate possible root causes of premature wind turbine gearbox failures and research improvement strategies. One area of work under the GRC is a collection and analysis effort of failure data titled the Gearbox Reliability Database (GRD), which was started in 2009. The main objectives of the GRD are to categorize top wind turbine gearbox failure modes, identify possible root causes, and direct future wind turbine gearbox reliability research and development (R) activities.

The GRD project has made huge progress in developing wind turbine gearbox reliability data collection tools,
standardizing data recording practices, populating the database, and informing the industry with up-to-date R findings and statistics. The project currently has more than 20 data-sharing partners, including wind turbine and wind turbine gearbox manufacturers and owners/operators, gearbox rebuild shops, and operation and maintenance service providers. The assets represented by only owner/operator partners on this project comprised approximately 34% of the U.S. capacity at the end of 2013 (according to the American Wind Energy Association annual market report). The number and variety of partners and the assets they represent demonstrate the value and need of major wind turbine component data collection and analysis to the industry.

The attached image shows the distribution of the damage component locations based on approximately 320 confirmable
wind turbine gearbox damage records stored in the database. It is observed that wind turbine gearboxes could fail in drastically different ways. The majority of the damage occurs to bearings (64%), followed by gears (25%), and the other
components account for 11% of the failures. Among the other components, lubrication and filtration system problems are dominant. Both bearing and gear faults are concentrated in the parallel section, which aligns with field observations made by wind turbine owner/operator partners. The top gearbox failure is axial cracks that occur to bearings located at the high- or intermediate-speed stage. This identification confirms the value and need for wind turbine gearbox R on bearing axial cracks root causes and mitigation methods, which is a joint research effort by Argonne National Laboratory and NREL funded by DOE's Wind and Water Power Program. The data-sharing partners highly value this project and recommend that NREL generate industry-wide reliability benchmarking statistics from the information contained in the database, which is currently not publicly available. Frequently, these reliability statistics are distorted and kept internally if they are generated by wind turbine original equipment manufacturers or owners/operators, which do not normally have a balanced representation of wind turbine makers and models. The GRD experiences provide the industry with valuable support to standardize reliability data collection for major wind turbine components and subsystems.