Modelling wind turbine tower-rotor interaction through an aerodynamic damping matrix

Abstract Current wind turbine modelling packages mainly adopt a complex methodology in which aerodynamic forces are coupled with the motion of the wind turbine components at every time step. This can result in long simulation run times, detrimental for the large number of simulations required for fatigue or reliability analyses. This contribution presents an efficient wind turbine modelling methodology based on blade element momentum theory and a linearization of the aerodynamic forces. This allows the wind-rotor interaction to be reduced to static forces applied at the tower top, with additional terms proportional to the tower velocities expressed as an aerodynamic damping matrix. This aerodynamic model was implemented as part of a finite element model of the tower and was successfully verified against the fully-coupled modelling package FAST. The damping matrix components explain key features of the coupling between fore-aft and side-side vibrations of the wind turbine. This coupling causes energy transfers between the two directions, complicating aerodynamic damping identification. The aerodynamic damping matrix offers novel insights and an efficient method to describe the aerodynamic damping of wind turbines.

[1]  Lars Vabbersgaard Andersen,et al.  Comparing Sources of Damping of Cross-Wind Motion , 2009 .

[2]  T. Belytschko,et al.  Computational Methods for Transient Analysis , 1985 .

[3]  Philippe Duffour,et al.  Modelling damping sources in monopile-supported offshore wind turbines , 2018, Wind Energy.

[4]  Daniel Rixen,et al.  Operational modal analysis of a 2.5 MW wind turbine using optical measurement techniques and strain gauges , 2013 .

[5]  Andrew T. Myers,et al.  Aerodynamic Damping and Seismic Response of Horizontal Axis Wind Turbine Towers , 2014 .

[6]  N. Troldborg,et al.  A simple atmospheric boundary layer model applied to large eddy simulations of wind turbine wakes , 2014 .

[7]  S. Adhikari,et al.  Identification of damping: Part 1, viscous damping , 2001 .

[8]  Yue Zhao,et al.  Structural vibration monitoring and operational modal analysis of offshore wind turbine structure , 2018 .

[9]  Sebastian Thöns,et al.  Vibration-based structural health monitoring of a wind turbine system. Part I: Resonance phenomenon , 2015 .

[10]  Markus Feldmann,et al.  On the Determination of the Aerodynamic Damping of Wind Turbines Using the Forced Oscillations Method in Wind Tunnel Experiments , 2019, Energies.

[11]  Anand Natarajan,et al.  Identification of support structure damping of a full scale offshore wind turbine in normal operation , 2015 .

[12]  Paul Fromme,et al.  Scour influence on the fatigue life of operational monopile-supported offshore wind turbines , 2018 .

[13]  Sumanta Haldar,et al.  Dynamic analysis of offshore wind turbine in clay considering soil–monopile–tower interaction , 2014 .

[14]  L. Freris.  Wind energy conversion systems , 1990 .

[15]  J. van der Tempel,et al.  Design of support structures for offshore wind turbines , 2006 .

[16]  Søren Nielsen,et al.  Identification of aerodynamic damping in wind turbines using time-frequency analysis , 2017 .

[17]  Paul Fromme,et al.  Fatigue life sensitivity of monopile-supported offshore wind turbines to damping , 2018, Renewable Energy.

[18]  Michael Muskulus,et al.  Decoupled simulations of offshore wind turbines with reduced rotor loads and aerodynamic damping , 2017 .

[19]  Martin Otto Laver Hansen,et al.  Aerodynamics of Wind Turbines , 2001 .

[20]  Daniel Rixen,et al.  Challenges in testing and monitoring the in-operation vibration characteristics of wind turbines , 2013 .

[21]  Ajit R Godbole,et al.  Effects of aerodynamic damping on the tower load of offshore horizontal axis wind turbines , 2017 .

[22]  Morten Hartvig Hansen,et al.  Two methods for estimating aeroelastic damping of operational wind turbine modes from experiments , 2006 .

[23]  Jim Woodhouse,et al.  The use of the sonogram in structural acoustics and an application to the vibrations of cylindrical shells , 1985 .

[24]  Enrique Simon Gutierrez-Wing,et al.  MODAL ANALYSIS OF ROTATING MACHINERY STRUCTURES , 2003 .

[25]  Patrick Guillaume,et al.  Structural health monitoring of offshore wind turbines using automated operational modal analysis , 2014 .

[26]  Jan Becker Høgsberg,et al.  Evaluation of damping estimates by automated Operational Modal Analysis for offshore wind turbine tower vibrations , 2018 .

[27]  Patrick Guillaume,et al.  Experimental and computational damping estimation of an offshore wind turbine on a monopile foundation , 2013 .

[28]  J. Jonkman,et al.  Definition of a 5-MW Reference Wind Turbine for Offshore System Development , 2009 .

[29]  M Muskulus,et al.  Simplified rotor load models and fatigue damage estimates for offshore wind turbines , 2015, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences.

[30]  Kaoshan Dai,et al.  Development of a modified stochastic subspace identification method for rapid structural assessment of in‐service utility‐scale wind turbine towers , 2017 .