A Possible Relation between Wind Conditions, Advanced Control and Early Gearbox Failures in Offshore Wind Turbines

During the past decades, great efforts have been undertaken to make wind power a competitive source for electrical energy. By the end of 2012, global installed wind capacity had risen to 264GW, almost a tenfold increase of the capacity in 2002. Nevertheless, the wind energy sector is still far too expensive to be profitable, especially the strong growing offshore branch. However, a significant part (about 25%) of the cost is related to operation and maintenance (O&M), in particular the failures of the main components (i.e. gearbox and drivetrain) resulting in long downtimes and hence high O&M costs. Various studies today discuss if condition monitoring systems, which allow the forecasting of failures at a very early stage, might be the cure to the problems related to the reliability of the gearbox. Rather than formulating yet another methodology to forecast upcoming failures, the aim of this paper is to identify the underlying cause of the reliability issues related to the gearbox.