Field Demonstration of Real-Time Wind Turbine Foundation Strain Monitoring

Area of Science:

• Structural Engineering
• Renewable Energy Technology
• Materials Science

Background:

• Onshore wind turbine foundations are often over-engineered due to difficulties in monitoring internal stress states during operation.
• There is a significant industry need for more economical foundation designs, which necessitates improved structural health monitoring techniques.

Purpose of the Study:

• To present initial results from a real-time strain monitoring campaign on an operating wind turbine foundation.
• To demonstrate the feasibility and potential benefits of real-time structural health monitoring for wind turbine foundations.

Main Methods:

• Instrumenting reinforcement bars within a concrete foundation using metal-packaged optical fiber strain sensors before casting.
• Collecting and analyzing 67 days of operational strain data.
• Correlating measured strains with tower displacements and finite element model results.

Main Results:

• Measured foundation strains remained below 95 μϵ during the monitoring period.
• A strong correlation was observed between foundation strains, tower displacements, and finite element model predictions.
• The study validates the achievability of real-time foundation monitoring.

Conclusions:

• Real-time monitoring of wind turbine foundations is technically feasible.
• This technology can help quantify the conservatism in existing design codes, paving the way for more economical and safe foundation designs.
• The results support the safe transition towards optimized wind turbine foundation engineering.