Trends in condition monitoring for pitch bearings

The value of wind power generation for energy sustainability in the future is undeniable. Since operation and maintenance activities account for a sizeable portion of the cost associated with offshore wind turbine operation, strategies are needed to decrease this cost. One strategy, condition monitoring (CM) of wind turbines, allows the useful life of several parts to be extended and has generated great interest in the industry. Pitch bearings are one type of critical component, by virtue of the time and logistics involved in their maintenance tasks. As the complex working conditions of pitch bearings entail the need for diverse and innovative monitoring techniques, the classical bearing analysis techniques are not suitable. This paper provides a literature review of several condition monitoring techniques. First, they are arranged according to the nature of the signal, such as vibration, acoustic emission and so on. Secondly, they are arranged by relevant authors in compliance with the signal nature. While little research has been performed, an outline is significant for further contributions to the literature.