Extended service life for wind turbines through a joint development project

Across Europe, a growing number of wind turbines are approaching their theoretical 20-year design life. This challenge is particularly evident in pioneer markets such as Sweden, where the industry is increasingly facing the question: is it possible to safely and cost-effectively extend the operational life of existing assets?

This was the starting point for a joint development project between Kiwa Sweden and a wind power industry operator. The aim was to develop and validate methods for assessing the potential life extension of wind turbine towers and foundations across several wind farms, with a focus on data-driven analyses and more efficient approaches for future lifetime assessments.

Combining measurement data, analyses and extensive experience

The project was built on Kiwa’s experience in lifetime extension assessments across several industries, including steel structures in rail, cranes and pressure vessels. A key aspect of the work was understanding how materials and structures are affected over time by variable and cyclic loading.
To assess the remaining useful life, data regarding the wind turbines’ structural design and operational history was collected. Calculation models were then developed for both towers and foundations. Loads were measured on selected wind turbines and correlated with historical operational data from the turbines’ SCADA systems (Supervisory Control and Data Acquisition).
By combining field measurements, operational data and engineering analyses, the project developed a methodology for assessing entire wind farms without the need for extensive load measurements on every individual turbine.

Many people see the design life as a fixed end date, but that is not necessarily the case. With the right analyses and the right mitigation measures, it is often possible to extend the service life by 10, 15 years or even longer.

Roger Wibert

Senior Engineer within Lifetime Extension at Kiwa

Providing a basis for continued safe operation and future development

The analyses provided the wind power operator with a clearer understanding of how much of the technical service life had actually been consumed, as well as which factors have the greatest impact on the remaining lifetime. So far, the towers and foundations in one wind farm have been approved for an additional 15 years of operation without major interventions.
At the same time, the project delivered a technically verified basis for decision-making regarding continued operation beyond the original design life, while also creating better opportunities to optimise future maintenance and operational strategies.

“When you understand which loads have the greatest impact on the structure, you can make smarter decisions regarding operations, maintenance and investments. It is about both safety and maximising the long-term value of the asset,” says Daniel Andersson, Senior Consultant at Kiwa.

A data-driven approach for the future of wind power

A central part of the development project was the correlation between load measurements and SCADA data. By combining historical operational data with measurements and calculation models, the analyses could be carried out both efficiently and with a high level of accuracy.
The methodology also creates opportunities for future analyses and testing programmes that may contribute to even longer lifetime extensions and a more proactive maintenance approach within the wind power industry.

“This is not only about extending the service life in the short term. The project has also contributed to developing a more long-term and data-driven approach to the operation and maintenance of wind farms,” concludes Roger Wibert.