The wind power industry has undergone and is still undergoing extensive development towards larger wind turbines. This means a large number of technical challenges and the results in many cases have left room for improvement even after the wind turbines have been installed. One of the causes of failure in wind turbines is that components of the turbines have been designed for prevailing operating conditions. Other causes of errors are flaws in the manufacture and installation of components. In many cases, the underlying mechanisms and phenomena leading to faults are not well understood.
Faults in wind turbines lead to direct costs for spare parts, maintenance equipment, personnel transport and maintenance to correct the errors. In addition there are indirect costs in terms of lost production. A reduction of these costs, and thus the cost of wind power in general, can be achieved by further improvements in the design of wind power components, which leads to an increased inherent reliability. The product development potential of individual critical components of the system is analysed. An approximate way of finding the most critical components is to study notional scenarios for the total maintenance costs of a wind turbine over its lifetime, where the expected service life for certain critical components varies.
Research has shown that today's maintenance, both on land and at sea, is not optimal. It has been shown that there are large potential savings to be made by optimising maintenance decisions during the service life to lower the total costs (a) of maintenance activities and component failure and (b) costs due to product losses. This is an important factor in the choice and the optimal implementation of the most appropriate maintenance strategy. With corrective maintenance, a component is used until it breaks down and it is then repaired. With preventive maintenance, components are maintained at predefined intervals or based on their condition to prevent the component failing.
Parallel to optimising maintenance management is the continued improvement of the inherent reliability of wind turbines and their components, which is important to reduce the failure rate. This is particularly important in offshore and remote wind farms where the limited accessibility has a major impact on the ability to measure faults. To achieve greater inherent reliability of wind power components a profound understanding of the physical mechanisms underlying the faults is needed. The advantage is not limited to future turbine generations but the results can also be used to improve the operation of existing wind farms, e.g. through retrofits.
Issues within Maintenance and Reliability are:
What are the appropriate methods for effective condition monitoring, to be able to detect, predict and prevent errors and deficiencies in the drivetrain? Specifically, how can the control system for frequency converters be used for this?
How is data from vibration-based CMS and SCADA-based CMS used to create an effective maintenance plan?
How are effective methods created to predict the remaining service life of damaged components when using fault signatures?
How is maintenance optimised to maximise the utilisation of the remaining service life of damaged critical components?
Which mechanisms underlie current-induced damage on bearings and how can these be understood (modelled) and limited or even prevented?
The following projects within the Centre fall under Theme group 5:
TG5-1 Load- and Risk-based Maintenance Management for Wind Turbines
TG5-2 Characterisation and modelling of bearing current activity
TG5-21 Optimal maintenance of wind power plants