Condition monitoring of a steam turbine generator using wavelet spectrum based control chart

Highlights: • Propose a condition monitoring scheme based on energy profiles generated from wavelet spectrum analysis. • Monitor the system based on multivariate T² chart for the parameters in the linear energy profiles. • The proposed approach is applied to temperature signals measured from a steam turbine generator. -- Abstract: Condition-based maintenance (CBM) is designed to take maintenance actions only when there is an imminent evidence of failure for a monitoring system. The parameters indicating health status of the system are continuously monitored in CBM. This article proposes a condition monitoring scheme based on energy profiles generated from wavelet spectrum analysis. The energy of time series is represented by a wavelet spectrum in scale representations of signals. After deriving wavelet spectrums using a discrete wavelet transform at pre-specified windows, we aim to monitor the system based on multivariate T² chart for the parameters in the linear energy profiles. The monitoring scheme is applied to temperature signals measured from a steam turbine generator. The proposed T² chart based on the energy profiles shows a potential in early detecting the abnormality of a monitoring system which is not clearly detectable in original time scales.