In order to understand the actual fatigue damage and remaining service life of wind turbines
it is crucial to conduct fatigue assessment of wind turbines based on vibration monitoring. Through long-term monitoring of tower bottom strain of a 1.5MW wind turbine
a new method for real-time prediction of fatigue damage was proposed based on the traditional four-point rainflow cycle counting algorithm. Traditional methods only considered stress cycles within subsets and ignored transition cycles between subsets. The new method proposed in this article predicted the current fatigue damage by concatenating residue series that could not form complete cycles in the past stresses with newly measured stresses. The new residue series were then stored and combined with subsequent measured stresses to evaluate the fatigue damage of wind turbines in real time. The fatigue damage obtained by using this method was identical to the results obtained by using known data as a continuous sequence
proving the accuracy of this method. At the same time
in this method only the residue series of historical data need to stored
which occupy less memory
this article also proveds that the accuracy of this method is not affected by the calculation window length. This provides a solution for online real-time prediction of fatigue damage in wind turbine structures.
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