Structural Monitoring in the Steel Tower of Wind Turbine
A wind turbine is mounted over 80 meters (approx.) high steel tower, which has the structure of a standing tube with varying diameter and wall thickness along the height. A prominent issue in the steel tower has been the dimensional fabrication tolerances of the ring flanges used to connect the tower segments. This is mainly responsible for the loss of contact between some parts of the flanges that leads to low performance of the bolts which remain subjected to higher stress ranges. To monitor these changes, structural monitoring of different levels of the tower is performed to identify the modal parameters and provide information about the evolution of the dynamic response.
For this purpose, strain gauges, along with vibration sensors and temperature sensors are allocated as part of the monitoring system. Strains are measured on the inner surface of the shell tower on the points distributed along the perimeter of the tube and inside the bolts per each assemble connections.
Gauge rosettes PFLR-20-11 from TML are employed to measure shell strains in two orthogonal directions, vertical and horizontal, and in a 45º-direction. These are foil strain gauges having polyester resin backing which is as in the P series. It is available in three gauge lengths 10, 20 and 30mm and is suited mainly to strain measurement on concrete or mortar.
To measure bolt tensile strains, the BTM-6C strain gauges are used. These gauges are simply inserted into a pre-drilled hole in the bolt with exclusive adhesives. With these gauges, accurate tensile force measurement is possible by calibrating the bolt after installing the bolt gauges.
Recommended Sensors:
