EurIng Tat-Hean Gan (CEng, IntPE(UK)) is the Technology Group Manager at TWI Ltd and Director of Brunel Innovation Centre (Brunel University). He has over 15 years of experience in the field of NDT. He received his PhD in Non-contact Air Coupled Ultrasonic Testing and Imaging from the University of Warwick UK and MBA at the University of Birmingham, UK. His research interest is in the NDT technique development (e.g. guided wave, digital radiography, phased array ultrasonics, electromagnetics), structural health and condition monitoring, sensors development (contact and non-contact), image and signal processing and electronics design. He has published over 90 technical papers and articles and has acted as referee for various journals such as Institute of Physics, IEEE Ultrasonics, Ferroelectrics and Frequency Control, Journal of Food Engineering, Ultrasonics journal and Journal of Renewable Energy. He is also an International Scientific Advisory Committee of the Condition Monitoring conference organized by BINDT and a Fellow of the Institute of Engineering and Technology (IET) and British Institute of Non-Destructive Testing (BINDT). Tat-Hean Gan received his Professorship from the Brunel University in 2009.

Abstract

Real-time monitoring system for defects detection in wind turbine structures and rotating components.

The wind turbine industry is one of the fastest growing markets in the renewable energy sector. Operation and maintenance (O&M) costs constitute a sizeable share of the total annual costs of a wind turbine. For a new wind turbine, the O&M costs may easily have an average share over the turbine lifetime of more than 30% of total levellised cost per kWh produced. Therefore, O&M costs are increasingly attracting the attention of manufacturers seeking to develop new designs requiring fewer regular service visits and less down-time. In order for the wind energy industry to achieve the growth targets set by the EU for the forthcoming years, the number of wind turbines has to increase substantially while their operation and maintenance costs have to be reduced by a noticeable factor to permit the European wind energy industry to retain its advantage over growing overseas competition. Therefore, one of the highest priorities for the European wind energy industry is currently the significant improvement in turbine reliability, involving a solid reduction in current inspection and maintenance costs mainly associated with unpredicted failures of the structures and critical rotating components. Presently in situ blade inspection is carried out every 6-12 month visually (binoculars etc) or with manual operatives involved in dangerous abseiling. This becomes difficult and hazardous due to the increasing trend towards remote offshore location of turbines. These factors directly contribute to the high maintenance cost, amounting to over 30% of overall operating costs when allowing for lost revenue.

This paper looks into the development of structural and condition monitoring systems for real time monitoring of wind turbine towers and blades, and machineries (including gearboxes). The structural health monitoring (SHM) system utilised guided wave technique for detecting flaws down to 3% cross sectional area loss on the tower. A combined SHM acoustic emission and guided wave technique is used for monitoring turbine blades. The condition monitoring system (CMS) on the other hand is developed from the acoustic emission and vibration techniques. The CMS system has successfully detected abnormal signatures attributable to shaft and gearbox defects. The developed systems operate by retrofitting onto the casing of the wind turbine rotating parts.