Extending the service life of wind turbines using research

As part of the ON PACE research project, The Hague University of Applied Sciences and technology company Sensing360 are working on a solution to extend the service life of offshore wind turbines.

The reason is surprising. Wind turbines do not run non-stop but are being temporarily shut down with increasing frequency. This happens, for example, when more electricity is generated than the grid can handle but also during severe storms or as a result of environmental measures. 'Wind turbines are built to run for the majority of the time’, explains Project Leader Sam Aerts of The Hague University of Applied Sciences. ‘Nowadays, forced downtime due to so-called “curtailment events”, such as severe weather or overcapacity, occur more frequently than the turbines were originally designed for. This has negative consequences for the planned lifespan of the mechanical parts.’

Wear caused by stopping

In particular, the act of bringing a rotating wind turbine to a standstill generates high forces in the drive system. After all, the energy stored in the rotating rotor blades has to go somewhere. These forces are transmitted, amongst other things, to the bearings, which are key parts that ensure moving parts continue to rotate smoothly.

The more frequently such strain occurs, the faster wear and tear sets in, leading to additional maintenance, higher costs and, ultimately, a shorter service life for turbines. ‘Slowing down wind turbines can, in the long run, have a significant impact on the service life of the bearings in the turbine’, explains Sam.

From measurement to prediction

As part of the ON PACE project, the project partners are investigating exactly how this wear and tear occurs. To this end, The Hague University of Applied Sciences uses a special test rig in which bearings are subjected to strain under controlled conditions. Using various sensors, researchers measure how a bearing responds to forces comparable to the strain in a real wind turbine. In doing so, the researchers look at vibrations, sound signals, and innovative fibre optic sensors that register deformations with great accuracy. ‘In the laboratory, we determine the exact force exerted on a bearing’, says Sam. ‘By linking that data to sensor readings, we gain a better understanding of what happens inside a real wind turbine. The collected data form the basis for new models that predict how quickly parts wear out and how much service life remains.'

Digital twin 

An important part of the project is the development of a so-called digital twin: a digital copy of the mechanism in a wind turbine. Using a model like this, researchers can simulate various scenarios. What happens, for example, if a turbine has to be stopped more often? How does that affect the bearings? And when is maintenance most efficient? Sam: ‘A digital twin enables us to simulate various future scenarios. This gives us a better understanding of the consequences of certain decisions and allows us to plan maintenance more effectively.’ 

Staying safe and profitable

As well as technical benefits, a digital twin also offers economic benefits. Wind farms represent huge investments, and many existing offshore turbines are approaching the end of their originally designed service life. ‘The pressing question is how long existing wind farms can continue to operate safely and profitably’, according to Sam. ‘That requires far more knowledge than is currently available.’

Open data for the sector

One striking aspect of the project is that the research findings will soon be widely available. The test rig generates large amounts of data on wear processes in bearings. That information is shared with the sector as open data. According to the project leader, there is a demand for such data. ‘Businesses often have their own data, which is usually limited. There is relatively little independent data available that would allow us to compare different situations. We hope that the results will ultimately lead to better predictive maintenance models and smarter decisions regarding the management of wind farms.’

Practice-oriented research

For Sam, the personal value of the project lies not only in its contribution to the energy transition but also in the opportunities it offers for students. Within ON PACE, students from degree programmes such as Mechanical Engineering, Electrical Engineering, Engineering Physics, and Applied Data Science work together on various aspects of the research. They help to develop sensors, analyse data and improve the test rigs. ‘This test environment is a brilliant learning platform. Students work together with companies and researchers from other disciplines on a real-world problem.’ 

Predictive maintenance

Predictive maintenance is becoming increasingly important in the wind turbine industry. This project demonstrates how education, research, and industry can work together to develop solutions that can be put into practice straight away. ON PACE contributes to a future in which offshore wind farms last longer, are maintained more intelligently, and can continue to deliver more sustainable energy.

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Would you like to know more about the project or collaborate? Check out the project page.