A Simple and Effective Real-Time Controller for Wave Energy Converters

A novel strategy for the real-time control of oscillating wave energy converters (WECs) is proposed. The controller tunes the oscillation of the system such that it is always in phase with the wave excitation force and the amplitude of the oscillation is within given constraints. Based on a nonstationary, harmonic approximation of the wave excitation force, the controller is easily tuned in real-time for performance and constraints handling, through one single parameter of direct physical meaning. The effectiveness of the proposed solution is assessed for a heaving system in one degree of freedom, in a variety of irregular (simulated and real) wave conditions. A performance close to reactive control and to model predictive control is achieved. Additional benefits in terms of simplicity and robustness are obtained.

[1]  A. Clément,et al.  Optimal Latching Control of a Wave Energy Device in Regular and Irregular Waves , 2006 .

[2]  T. Moan,et al.  Constrained Optimal Control of a Heaving Buoy Wave-Energy Converter , 2011 .

[3]  Pierpaolo Ricci,et al.  Control strategies for a wave energy converter connected to a hydraulic power take-off , 2011 .

[4]  Gordon Lightbody,et al.  An Application of Model Predictive Control to a Wave Energy Point Absorber , 2010 .

[5]  W. Marsden.  I and J , 2012 .

[6]  Fuat Kara,et al.  Time domain prediction of power absorption from ocean waves with latching control , 2010 .

[7]  Boualem Boashash,et al.  Estimating and interpreting the instantaneous frequency of a signal. I. Fundamentals , 1992, Proc. IEEE.

[8]  John Ringwood,et al.  Suboptimal Causal Reactive Control of Wave Energy Converters Using a Second Order System Model , 2011 .

[9]  Gordon Lightbody,et al.  A Critical Assessment of Latching As Control Strategy For Wave-Energy Point Absorbers , 2011 .

[10]  Tristan Perez,et al.  Time- vs. frequency-domain identification of parametric radiation force models for marine structures at zero speed , 2008 .

[11]  Michael G. Egan,et al.  Development of an electrical power take off system for a sea-test scaled offshore wave energy device , 2011 .

[12]  Ping Ju,et al.  Optimal Control for AWS-Based Wave Energy Conversion System , 2009, IEEE Transactions on Power Systems.

[13]  Boualem Boashash,et al.  Estimating and interpreting the instantaneous frequency of a signal. II. A/lgorithms and applications , 1992, Proc. IEEE.

[14]  Johannes Falnes,et al.  Wave-Energy Conversion Through Relative Motion Between Two Single-Mode Oscillating Bodies , 1999 .

[15]  J. Ringwood,et al.  A control system for a self-reacting point absorber wave energy converter subject to constraints , 2011 .

[16]  João C. C. Henriques,et al.  Reactive versus latching phase control of a two-body heaving wave energy converter , 2009, 2009 European Control Conference (ECC).

[17]  Jaroslaw Figwer.  A new method of random time-series simulation , 1997, Simul. Pract. Theory.

[18]  T Moan,et al.  Wave Prediction and Robust Control of Heaving Wave Energy Devices for Irregular Waves , 2011, IEEE Transactions on Energy Conversion.

[19]  Yonghua Song,et al.  A Comprehensive Review on the Development of Sustainable Energy Strategy and Implementation in China , 2010, IEEE Transactions on Sustainable Energy.

[20]  John Ringwood,et al.  Comparison of Two Alternative Hydraulic PTOConcepts for Wave Energy Conversion , 2011 .

[21]  M. Ochi.  Ocean Waves: The Stochastic Approach , 1998 .

[22]  Jonathan Shek,et al.  Reaction force control of a linear electrical generator for direct drive wave energy conversion , 2007 .

[23]  F. Fusco,et al.  A Study of the Prediction Requirements in Real-Time Control of Wave Energy Converters , 2012, IEEE Transactions on Sustainable Energy.

[24]  Johannes Falnes,et al.  A REVIEW OF WAVE-ENERGY EXTRACTION , 2007 .

[25]  Ted K.A. Brekken,et al.  Reserve requirement impacts of large-scale integration of wind, solar, and ocean wave power generation , 2010, IEEE PES General Meeting.

[26]  Evanghelos Zafiriou,et al.  Robust process control , 1987 .

[27]  Paolo Mattavelli,et al.  Effect of Control Strategies and Power Take-Off Efficiency on the Power Capture From Sea Waves , 2011, IEEE Transactions on Energy Conversion.

[28]  Francesco Fusco,et al.  Variability reduction through optimal combination of wind/wave resources – An Irish case study , 2010 .

[29]  Tor Onshus,et al.  The Norwegian wave-power buoy project , 1982 .

[30]  J. Uhlmann,et al.  Implicit Jacobian for linearised state estimation in nonlinear systems , 1995, Proceedings of 1995 American Control Conference - ACC'95.

[31]  José J. Cândido,et al.  Modelling, control and Pontryagin Maximum Principle for a two-body wave energy device , 2011 .

[32]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.

[33]  J. Falnes.  Ocean Waves and Oscillating Systems , 2002 .

[34]  John V. Ringwood,et al.  A predictive controller for a heaving buoy producing potable water , 2009, 2009 European Control Conference (ECC).

[35]  Francesco Fusco,et al.  Short-Term Wave Forecasting for Real-Time Control of Wave Energy Converters , 2010, IEEE Transactions on Sustainable Energy.