Control design methods for floating wind turbines for optimal disturbance rejection

An analysis of the floating wind turbine as a multi-input-multi-output system investigating the effect of the control inputs on the system outputs is shown. These effects are compared to the ones of the disturbances from wind and waves in order to give insights for the selection of the control layout. The frequencies with the largest impact on the outputs due to limited effect of the controlled variables are identified. Finally, an optimal controller is designed as a benchmark and compared to a conventional PI-controller using only the rotor speed as input. Here, the previously found system properties, especially the difficulties to damp responses to wave excitation, are confirmed and verified through a spectral analysis with realistic environmental conditions. This comparison also assesses the quality of the employed simplified linear simulation model compared to the nonlinear model and shows that such an efficient frequency-domain evaluation for control design is feasible.

[1]  J. Jonkman.  Influence of Control on the Pitch Damping of a Floating Wind Turbine , 2008 .

[2]  David Schlipf,et al.  Parametric Wave Excitation Model for Floating Wind Turbines , 2016 .

[3]  Torben J. Larsen,et al.  A method to avoid negative damped low frequent tower vibrations for a floating, pitch controlled wind turbine , 2007 .

[4]  Robert Seifried,et al.  Reduced nonlinear model of a spar-mounted floating wind turbine , 2012 .

[5]  Alan Wright,et al.  Evaluating Methods for Control of an Offshore Floating Turbine , 2014 .

[6]  Jason Jonkman,et al.  Wind/Wave Misalignment in the Loads Analysis of a Floating Offshore Wind Turbine , 2014 .

[7]  Thor Inge Fossen,et al.  Optimal Control of Floating Offshore Wind Turbines , 2009 .

[8]  Petter A. Berthelsen.  Qualification of innovative floating substructures for 10MW wind turbines and water depths greater than 50m , 2015 .

[9]  David Schlipf,et al.  Wind Turbine Controller to Mitigate Structural Loads on a Floating Wind Turbine Platform , 2016, Journal of Offshore Mechanics and Arctic Engineering.

[10]  David Schlipf,et al.  Model of the Correlation between Lidar Systems and Wind Turbines for Lidar-Assisted Control , 2012 .

[11]  Lucy Y. Pao,et al.  Collective pitch feedforward control of floating wind turbines using lidar , 2015 .

[12]  David Schlipf,et al.  Prospects of Linear Model Predictive Control on a 10 MW Floating Wind Turbine , 2015 .

[13]  L. Henriksen,et al.  The DTU 10-MW Reference Wind Turbine , 2013 .

[14]  Johan Peeringa,et al.  Control development for floating wind , 2014 .

[15]  Jason Jonkman,et al.  FAST User's Guide , 2005 .

[16]  Boris Fischer,et al.  Reducing rotor speed variations of floating wind turbines by compensation of non-minimum phase zeros , 2013 .

[17]  J. Landaluze,et al.  H∞ Based Control for Load Mitigation in Wind Turbines , 2012 .

[18]  Ian Postlethwaite,et al.  Multivariable Feedback Control: Analysis and Design , 1996 .

[19]  David Schlipf,et al.  Integrated optimization of floating wind turbine systems , 2014 .

[20]  Hazim Namik,et al.  Individual Blade Pitch and Disturbance Accommodating Control of Floating Offshore Wind Turbines , 2012 .

[21]  William Leithead,et al.  Coordinated control design for wind turbine control systems , 2006 .