New technologies for wind turbines foundation repair.

Introduction

In the past years many faults in the foundations of wind turbines around the world have been detected. Even when it is a matter subject to a strong degree of confidentiality, it is known that thousands of foundations, all over the world have been cracked, allowing movements inadmissible by the turbines. This communication presents for the first time, the fully satisfactory result of repair work of more than 300 foundations in various countries of Europe in the last decade. As an image is worth a thousand words, a link to a video of 5 mn which summarizes this work is included below.
https://www.dropbox.com/s/6ezxnhuj04u32le/WIND%20EUROPE%20ABSTRACT%202016.mp4?dl=0


Approach

In 2007, a wind farms owner reported us a serious problem affecting hundreds of foundations of wind turbines: there were movements, increasing with time, forcing its decommissioning. The challenge was to find a technology able to meet the following requirements:
• Long-lasting solution.
• Minimize the turbine downtimes.
A system, inspired by the repair of dams, has been developed, using high viscosity synthetic resins, injected at very high pressure, has been shown, after nine years of the first experiences, to fulfill the above requirements.


Main body of abstract

Since the 1990's we have been repairing leaks in dams, regardless of its flow and pressure of water, without drawdown the reservoir or the use of divers. Leakage of up to 300 l/sec and more than 200 meters water column has been sealed, recovering the monolithism of the dam. This technology, applied in more than 200 dams in Middle East, Europe and America, is based on the use of very high viscosity resins, specially formulated, injected at very high pressure.
Based on this extensive experience, dam technology has been adapted to the foundations of wind turbines. The aim was to return the monolithic concrete fractured under the flange and encapsulate the ferrule on its pedestal, with a strong and elastic material, minimizing the movements and ensuring the durability of the repair.
Resins have been especially formulated for this application, as well as machinery and working procedures, suitable for any environment. Foundations in areas close to the Arctic or southern Spain where temperatures exceed 40 degrees have been successfully repaired.
In terms of loss of profits, the total downtime for repairing each wind turbine has been reduced to only three days.
In terms of effectiveness, given the perspective of nine years of experience and more than 300 foundations repaired in extreme latitudes of the northern hemisphere, is concluded that the repair technology ensures a stable performance of the foundation.


Conclusion

New materials and technology developed especially for repairing wind turbines foundations, after nine years of experience and more than 300 units repaired in different latitudes of Europe allow to conclude that a mature methodology is ready to be launched with full guarantees of success.
Its main strengths are:
• Reduces movements to permissible values, not suffering significant increases in time.
• Executable in any environment or temperature.
• Minimizes the turbine downtime to three days.



Learning objectives
So far the technology diffusion has been done almost by word of mouth, beginning in Spain, and continuing in France and Sweden. After more than three hundred repaired foundations and nine years monitoring its behavior, we consider the technology is mature enough to be presented, for the first time at a Conference.
The versatility of its application, the reduced time required for its execution and its excellent performance over time, make us consider that it is an interesting topic to be presented in Wind Europe 2016.