Resonance Monitoring of a Horizontal Wind Turbine by Strain-Based Automated Operational Modal Analysis

Abstract

A strain-based automated operational modal analysis algorithm is proposed to track the long-term dynamic behavior of a horizontal wind turbine under operational conditions. This algorithm is firstly validated by a scaled wind turbine model, and then it is applied to the dynamic strain responses recorded from a 5 MW wind turbine system. We observed variations in the fundamental frequency and 1f, 3f excitation frequencies due to the mass imbalance of the blades and aerodynamic excitation by the tower dam or tower wake. Inspection of the Campbell diagram revealed that the adverse resonance phenomenon and Sommerfeld effect causing excessive vibrations of the wind tower.

Dynamic Performance of Monopile-Supported Wind Turbines (MWTs) under Different Operating and Ground Conditions

“…To conclude, when using this method, the modal parameters of the operating MWT standing on sandy ground can be identified with reliable precision. Similar applications of this method have been widely adopted in the literature [19,40]. The f and ξ of the MWT under different operating and ground conditions are identified and discussed in following sections.…”

“…Stochastic subspace identification [39,40] was employed to identify the modal parameters according to the tower acceleration (see Figure 9). As is shown in Figure 9a, Acc1, Acc2, and Acc3 represent the accelerometers at the top, middle, and base of the tower, respectively.…”