Semi-active frequency tracking algorithm for control of flapwise vibrations in wind turbine blades

The increased size and flexibility of modern multi-Megawatt wind turbines has lead to their dynamic behaviour becoming an important design consideration. The aim of this paper is to develop a semi-active control algorithm using Semi-Active Tuned Mass Dampers (STMDs) to reduce vibrations in the flapwise direction. The model developed in this study considers only the structural dynamics of the turbine and includes the coupling between the blades and tower. The algorithm developed uses a frequency tracking technique based on the Short Time Fourier Transform (STFT). This allows real-time tuning of the dampers to the dominant frequencies in the system. Numerical simulations have been carried out to study the effectiveness of the STMDs for steady and turbulent wind loading.