Use of strain monitoring data for fatigue assessment of wind turbine tower

Abstract

The main goal of the WindFarmSHM research project is the development, validation and optimization of a monitoring strategy to be applied at the level of the wind farm, which should be able to evaluate the structural condition of a set of wind turbines and their consumed fatigue life. The accomplishment of this goal implies developing an experimental campaign, the construction of numerical models and the implementation of new data processing methodologies. The experimental campaign involves the simultaneous instrumentation of several wind turbines in the same wind farm with various sensors. In the present paper, only the strain measurement performed in the tower of one wind turbine will be analyzed. In a first step, the experimental determination of bending moments at the tower requires the acquired raw data to be preprocessed to obtain the actual deformation. Thus, special attention is given to strain signals processing, which includes temperature effects compensation and signal calibration according to IEC 61400-13. Afterwards, the procedures for fatigue assessment, based on S-N curves and on the Palmgren-Miner rule, are applied, analyzing the sensitivity of the results to the adopted window length of the strains time series and S-N curve types. Advanced numerical models of the wind turbine are also being developed in FAST. The experimental results reported in this contribution are compared with their numerical counterparts. The application of the developed tools and the data recorded over more than a year allowed to obtain very relevant results for the fatigue assessment of the tower under analysis. (c) 2021 International Conference on Structural Health Monitoring of Intelligent Infrastructure: Transferring Research into Practice, SHMII. All rights reserved.