Analysis of electrical power data for condition monitoring of a small wind turbine

Certain parts of a wind turbine, for example, the gearbox require significant time and heavy lifting equipment in the event of catastrophic failure necessitating replacement. Continuous condition monitoring has the potential to catch problems early, enable preventative maintenance and thereby reduce turbine downtime and prevent secondary damage. Accelerometers applied to mechanical components of the drive train are traditionally used for condition monitoring but require their own data acquisition system and analysis software. In contrast, the electrical current and voltage are continuously measured and could also be used for condition monitoring more cheaply. An experimental data acquisition system has been installed on a small (25kW) onshore turbine in Leicestershire, UK to compare 6 electrical power signals with 6 accelerometer signals. Data have been recorded before and after a gearbox failure and replacement. Data were analysed using both Fourier Transform and Morlet Continuous Wavelet Transform methods. Results show that the electrical data do indeed show the same principal vibration frequencies as the accelerometers and could therefore be used for condition monitoring.