Model Predictive Control of a Direct Wave Energy Converter Constrained by the Electrical Chain using an Energetic Approach

The control strategy for Direct Wave Energy Converters (DWEC) is often discussed without taking into account the physical limitations of electric Power TakeOff (PTO) system. This inappropriate modelling assumption leads to a non-realistic or a bad use of the electric systems, that leads to a failure to minimize the global " per-kWh " system cost. We propose here a Model Predictive Control (MPC) that takes into account the main limits of an electrical chain: maximum force, maximum power and a simplified loss model of the electrical chain. To compare this optimal control with other strategies, we introduce the notions of control, electric and global energy efficiencies. Furthermore, we use an original energy representation used to value the state at the end of the MPC horizon. Finally, we make several sensitivity study on the constraint limits for an economical pre-sizing of the electrical chain.

[1]  J. Gallego,et al.  INTRODUCTION TO OPTIMAL CONTROL THEORY , 1985 .

[2]  John V. Ringwood,et al.  Energy-Maximizing Control of Wave-Energy Converters: The Development of Control System Technology to Optimize Their Operation , 2014, IEEE Control Systems.

[3]  Marta Molinas,et al.  Tunable Control Strategy for Wave Energy Converters With Limited Power Takeoff Rating , 2012, IEEE Transactions on Industrial Electronics.

[4]  Bernard Multon,et al.  Influence of IGBT current rating on the thermal cycling lifetime of a power electronic active rectifier in a direct wave energy converter , 2013, 2013 15th European Conference on Power Electronics and Applications (EPE).

[5]  Gordon Lightbody,et al.  Maximisation of Energy Capture by a Wave-Energy Point Absorber using Model Predictive Control , 2011 .

[6]  B. Multon,et al.  Influence of control strategy on the global efficiency of a Direct Wave Energy Converter with electric Power Take-Off , 2013, 2013 Eighth International Conference and Exhibition on Ecological Vehicles and Renewable Energies (EVER).

[7]  Harry Zheng,et al.  A maximum principle for optimal control problems with mixed constraints , 2001 .

[8]  John V. Ringwood,et al.  Robust control of wave energy converters , 2014, 2014 IEEE Conference on Control Applications (CCA).

[9]  Bernard Multon,et al.  Sizing Optimization Methodology of a Surface Permanent Magnet Machine-Converter System Over a Torque-Speed Operating Profile: Application to a Wave Energy Converter , 2012, IEEE Transactions on Industrial Electronics.

[10]  Bernard Multon,et al.  Enhanced Aging Model for Supercapacitors Taking Into Account Power Cycling: Application to the Sizing of an Energy Storage System in a Direct Wave Energy Converter , 2015, IEEE Transactions on Industry Applications.

[11]  Marta Molinas,et al.  Self-sustained all-electric wave energy converter system , 2014 .

[12]  Edo Abraham,et al.  Optimal active control of a wave energy converter , 2012, 2012 IEEE 51st IEEE Conference on Decision and Control (CDC).

[13]  Pierre-Brice Wieber,et al.  Fast Direct Multiple Shooting Algorithms for Optimal Robot Control , 2005 .

[14]  Marta Molinas,et al.  Exploring the Potential for Increased Production from the Wave Energy Converter Lifesaver by Reactive Control , 2013 .

[15]  Guang Li,et al.  Model predictive control of sea wave energy converters – Part I: A convex approach for the case of a single device , 2014 .

[16]  Aurélien Babarit,et al.  Effect of non-ideal power take-off on the energy absorption of a reactively controlled one degree of freedom wave energy converter , 2014 .

[17]  A H Clément,et al.  Discrete control of resonant wave energy devices , 2012, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences.

[18]  Bernard Multon,et al.  Simulation of electricity supply of an Atlantic island by offshore wind turbines and wave energy converters associated with a medium scale local energy storage , 2006 .

[19]  Antonio de la Villa Jaén,et al.  Maximizing output power of linear generators for wave energy conversion , 2014 .

[20]  Aaron Strauss.  Introduction to Optimal Control Theory , 1968 .