Mechanical Systems and Signal Processing 70-71 (2016) 161–175, 2015

Autocorrelation-based time synchronous averaging for condition monitoring of planetary gearboxes in wind turbines

Jong M. Haa, Byeng D. Youn a, Hyunseok Ohb, Bongtae Han b, Yoongho Jung c, and Jungho Park a

aDepartment of Mechanical and Aerospace Engineering
Seoul National University, Seoul 151-742, Republic of Korea

bCALCE, Department of Mechanical Engineering
University of Maryland, College Park, MD 20742, USA

cSchool of Mechanical Engineering,
Pusan National University, Pusan 609-735, Republic of Korea


We propose autocorrelation-based time synchronous averaging (ATSA) to cope with the challenges associated with the current practice of time synchronous averaging (TSA) for planet gears in planetary gearboxes of wind turbine (WT). An autocorrelation function that represents physical interactions between the ring, sun, and planet gears in the gearbox is utilized to define the optimal shape and range of the window function for TSA using actual kinetic responses. The proposed ATSA offers two distinctive features: (1) data-efficient TSA processing and (2) prevention of signal distortion during the TSA process. It is thus expected that an order analysis with the ATSA signals significantly improves the efficiency and accuracy in fault diagnostics of planet gears in planetary gearboxes. Two case studies are presented to demonstrate the effectiveness of the proposed method: an analytical signal from a simulation and a signal measured from a 2 kW WT testbed. It can be concluded from the results that the proposed method outperforms conventional TSA methods in condition monitoring of the planetary gearbox when the amount of available stationary data is limited.

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