Methods to improve wind turbine generator bearing temperature imbalance for onshore wind turbines

Abstract

For better annual energy production, wind turbine generator components are expected to perform efficiently and safely. Development of recent high-efficiency generators and motors leading their designs with less cooling capacity. Bearings are one of the most stressed components in the generator. Recent studies have indicated that bearing failure is the prime cause of generator failure, in wind turbine application. Grease lubrication deterioration was found to be the leading cause of motors and generators bearing failure. Grease service life for generators are closely associated with the operating temperature. One issue with the less cooling design is the higher bearing temperature. This led to marginal lubrication, premature bearing failure, and reduce generator reliability. To verify this and address the issue of inadequate and imbalanced bearing cooling; this paper presents recent experimentation performed on-air to air-cooled squirrel cage induction generator. This test addresses a potential issue with the IC6A1A6 cooled generator design and recommends the updates with corresponding standards. To get optimal bearing life and generator reliability, either allowed bearing operating temperature range should be reduced significantly, by developing a new cooling strategy or standards committee should come up with different intervals of lubrication for both ends of the bearings. Issues similar to with IEEE standard 841 high-efficiency motors can be avoided, where a study performed on the reliability of these motors used in refinery confirmed that motors are at greater risk. A proactive plan based on the result and recommendations in this paper will help to secure the safe wind turbine-generator operation.