Energy Efficiency

Using wind turbines to maximize productivity, reduce costs

Wind turbines can achieve an online availability of about 98%, giving operators approximately one week in the year when planned maintenance can be completed. It is essential to use this time efficiently, concentrating on the most important issues, which can be identified using preventive maintenance techniques.

By Jason Horton, Sulzer December 10, 2017

Preserving the reliability of a wind turbine is essential for keeping it operational and cost effective. By working to prevent potential failures, condition monitoring and repair work can be planned ahead of time, ensuring any downtime is minimized. This concept can include predictive maintenance procedures such as vibration analysis as well as onsite repairs or modifications to resolves issues.

Since wind turbines were first commissioned on an industrial scale, the technology and design of the components has progressed rapidly, enabling units over 1 MW to be installed with an expected working life of around 20 years. As each new design comes to market, it incorporates the lessons learned from its predecessors, but also has the potential to introduce its own issues.

Planned and reactive strategies

Creating a comprehensive maintenance strategy for wind turbines requires considerable expertise in the various parts of rotating equipment, the systems behind the electronic control panels, as well as flexible field service teams that can provide planned and reactive repair solutions to remote areas. However, the original equipment manufacturers (OEMs) will generally only look after their own equipment, which can lead to a complex set of arrangements for each turbine.

Developing a partnership with an experienced, independent provider can deliver a number of advantages and has the potential to maximize maintenance efficiency and allow all the components within an installation to be covered by experienced engineers from a single source.

In addition, a greater breadth of experience, supported by expert design engineers, allows modifications to the original components to be introduced to improve durability. By delivering these as part of a planned schedule, productivity can be maximized and component failures avoided. Dedicated resources deployed to both onshore and offshore generating facilities can reduce downtime and maintenance costs compared to either a workshop repair or complete replacement in many cases.

Repair instead of replace

Take, for example, an offshore turbine generator that failed due to a rotor earth fault. With the accumulated costs of a crane barge, a new generator and the associated labor costs, the most likely outcome would have been decommissioning the turbine.

However, a team of specialist engineers visited the turbine, confirmed the original fault finding analysis and disassembled the generator for further inspection. Several new parts were installed, including slip rings and brush gear assemblies before reassembly and testing.

Once the turbine was reconnected to the grid, it was generating the required output and normal operation was resumed. In all, the on-site work had taken the engineers 20 hours but had saved the wind turbine from being decommissioned and also improved its reliability for the future.

The root cause of the fault was identified as carbon contamination, which had led to electrical tracking between phase and earth through insulated components. This failure mechanism could have been avoided using regular, professional maintenance, which requires in-depth generator knowledge.

This example illustrates how expert advice can drastically change the outcome of a situation and very often can save time and money in the long term. As wind energy continues to grow as a source of power, the importance and requirement for a reliable repair partner can provide monitored maintenance solutions, with an understanding of how wind turbines operate, will become more prevalent. This will especially be the case as larger turbines evolve and their location moves further offshore.

Jason Horton, regional operations director (South), Sulzer. Edited by Chris Vavra, production editor, Control Engineering, CFE Media,