Main bearings in large offshore wind turbines: development trends, design and analysis requirements

Abstract

This paper discusses analysis requirements for design and operation of main bearings in modern multi-megawatt offshore wind turbines, motivated by the industry's search for reliable and cost effective main bearing solutions that limit the effects of non-torque loads, and the need for effective bearing health monitoring. Gearboxes historically received attention on the grounds of reliability, sparking significant interest in drivetrain dynamics. However, design trends in modern, large turbines, influencing choices for a future 10+ MW generation, indicate that more attention to main bearings or rotor support bearings is needed as part of a more holistic approach to flexural dynamics. Through a survey of existing research, offshore wind turbine design trends, design codes, industry practices and standards, we look at how main bearings are treated in a life cycle perspective, considered design features, modeling and simulation approaches, interaction and interfaces between industry stakeholders, as well as reuse of simulation models for predictive analytics in operation. We conclude that flexible main bearing representation is important in dynamic analyses and that industry practices are needed that enable sufficient model exchange or interfaces and thus effective exploitation of the benefits of a simulation model throughout the turbine life cycle.