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

This paper is a postprint of a paper submitted to and accepted for publication in IET Renewable Power Generation and is subject to Institution of Engineering and Technology Copyright. The copy of record is available at IET Digital Library.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 scheduled preventative maintenance and thereby reduce turbine downtime, reduce the number of site visits 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 three-phase currents and voltages on the stator windings with six 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 stator voltages show the same radial and axial mode vibration frequencies as the accelerometers and could therefore be used for condition monitoring. Furthermore, the stator currents show torsional modes of vibration not picked up by the accelerometers

Review of magnetic gear technologies and their applications in marine energy

The marine energy industry is in its early stages but has a large potential for growth. One of the most significant challenges is the reduction of operation and maintenance costs. Magnetic gears (MGs) offer the potential for long periods between maintenance intervals due to their frictionless torque transmission which could reduce these costs. This study presents a summary of the state of the art in MG technology and then investigates its potential for marine energy applications. A brief overview is given of the state of the marine energy industry and the environment in which marine energy converters (MECs) operate. A short history of MG development over the past century is then presented followed by a discussion of the leading MG technologies and their relative advantages. In order to demonstrate the potential of MGs in marine applications, the current technologies, i.e. mechanically geared and direct drive machines, are examined in terms of sizing, reliability and economic value using previous studies on a similar technology, namely wind. MGs are applied to four types of MECs to demonstrate how the technology can be incorporated. The potential to deploy at scale and potential obstacles to this are then discussed