Wind energy system has two key requirements for bearings: high performance and long service life under harsh conditions. These requirements are particularly applicable to offshore wind farms where wind turbine capacity is still increasing. The bearing for the NSW stage has recently been developed for the NSK turbine stage.
However, it is not only performance capability that puts forward high requirements for wind turbine bearings. In the sea, because the wind speed is very high, even more static and dynamic loads act on the rotor, so the load of the whole transmission system is very large. In the onshore wind turbine, the load of the main bearing is as high as 1MN; in the offshore wind turbine, the load is greater.
In view of this, higher and higher requirements are put forward for the service life of wind turbine bearings. For onshore turbines, the manufacturer has traditionally specified that the design life of the bearing must be 175000 hours, equivalent to 20 years. However, due to the high investment cost and difficult access of offshore wind energy systems, a 25 year service life is required, which is a major challenge to take into account extremely high dynamic loads.