Dynamic and flexible characteristics of pitch bearing in wind turbine

HE Xian-zhao1,2, LIU Yong1,2, TANG Yong-jiang1,2, YU Qing-qing1,2, ZHU Chang-jiang1,2
（1.Zhejiang Windey Co., Ltd., Hangzhou 310000, China; 2.Key Laboratory of Wind
Power Technology of Zhejiang Province,Hangzhou 310000, China）

Abstract: Aiming at the problem that the dynamic characteristics of pitch bearing could not be reflected with traditional pitch bearing analyzing method due to the rigid assumption, online test and numerical simulation techniques were introduced to study the dynamic and flexible characteristics of pitch bearing.The characteristics of load distribution in working pitch bearing were studied, and an online test method based on strainload measurement and displacement sensor was proposed, to measure the axial and radial displacements of internal and external rings, and the load of pitch bearing at various powers. A finite element model of pitch system was developed with the flexibilities of pitch bearing and surrounding structures incorporated, and finite element analyses were performed with the tested loads as inputs. Finally the tested and simulated dataofthe axial and radial displacements at different positions of pitch bearing at different powers were compared. The results indicate that the load, axial and radial displacementsof pitch bearing change regularly at different positions with different characteristicsas the wind rotor operates, which shows the dynamic and flexible characteristics of the pitch bearing, and such characteristics can be used to guide the study of pitch bearing reliability.
Key words: wind turbine; pitch bearing; axial displacement; radial displacement; dynamic and flexible characteristics