There is a growing interest in monitoring techniques and systems which can provide information about the condition of a wind turbine support structure, owing to a number of operational factors which have become apparent as increased numbers of turbine installations are experiencing longer periods of time in service. These include:
• Instances of fatigue cracking in the support towers
• Flange bolts at the ends of the tower sections becoming loose
• Higher than expected levels of vibration, which could cause either of the above mechanisms
• Degradation of the grouted joint between the pile and transition piece in offshore installations.
Wind farm operators are becoming increasingly concerned at the inability to predict remaining life of the installations, as this a rapidly expanding sector and there is little information about likely rates of structural degradation and failure modes. In addition, experience from operation of older wind farms is of limited value, because the specification of these installations is evolving rapidly, with the capacity (and therefore size and weight) of the generator becoming larger and the consequent dimensions of the tower increasing. The effect is that it is very difficult to extrapolate experience with existing structures to the likely behaviour of new ones.
On these installations there are very large surface areas/volumes of material to be examined and degradation may occur almost anywhere, so that the inspection task is not trivial. Furthermore, there is no established structural monitoring industry dedicated to the wind sector.
The aim of this project is the development of suitable and reliable techniques for monitoring of wind turbine tower structures and joint that could suffer from grout damage and slippage.
This project will also develop a best practice and standardisation of the methods involved and that a programme of information and training for inspection personnel is produced and implemented.