Use of the Teager-Kaiser energy operator for condition monitoring of a wind turbine gearbox

This paper deals with the condition monitoring of a wind turbine gearbox under varying operating conditions, which cause nonstationarity. The gearbox vibration signals are decomposed into a set of monocomponent signals using the Empirical Mode Decomposition (EMD) method. The Teager-Kaiser Energy Operator (TKEO) in combination with an energy separation method is also presented as an alternative technique that seems to improve the time-frequency analysis of signals. In this study, the TKEO is applied to the signal components who’s frequency bandwidth is related to the frequencies more influenced by damage. The Teager-Kaiser energy operator is a nonlinear operator that calculates the energy of monocomponent signals as the product of the square of the amplitude and the frequency of the signal. The instantaneous characteristics of these signals are then obtained by the application of the Discrete Energy Separation Algorithm (DESA-2). It will be shown that TKEO improves the estimation of instantaneous characteristics of the vibration data compared to other commonly used techniques, e.g. the Hilbert Transform.