An integrated monitoring scheme for wind turbine main bearing using acoustic emission

•An integrated monitoring method based on acoustic emission is proposed for ultra-low speed bearing fault diagnosis.•A rotating speed estimation approach is developed to recover the accurate operating speed of the main bearing.•An adaptive spectral coherence is explored to identify faulty narrowband buried under multiple disturbances.•An effective damage localization model is constructed to improve the health management efficiency of the main bearing in wind farms.•The proposed method can not only effectively detect the incipient damage of the main bearing, but also accurately determine the damage location.