Maximising power conversion for heaving point absorbers using a reference-based control technique

Maximising power conversion for heaving point absorbers using a reference-based control technique

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This study considers maximising conversion between the mechanical and electrical powers for heaving point absorbers (HPAs). The objective is implemented by generating the buoy's velocity reference by designing the intrinsic resistance. The authors designed the intrinsic resistance using a rapid procedure involving the mechanical and electrical models of HPAs. The electrical power conversion can be improved by tuning a weighting constant with the constraints on the maximum value of the control force and the power take-off utilisation index. The value of the intrinsic resistance is varied based on irregular sea states, which are characterised by their significant heights and peak angular frequencies. A simple robust proportional-integral-derivative (PID) controller is utilised in the servo feedback control system to follow the velocity reference. The PID controller is designed using the complex polynomial stabilisation to convert the robust performance into a set of linear programming problems. A set of admissible PID controller is obtained to satisfy the robust performance specifications. The authors tested the proposed method in various nominal and perturbation scenarios, and its performance was compared with existing reference and non-reference based HPA control strategies.


    1. 1)
      • 1. Falnes, J.: ‘Ocean waves and oscillating systems’ (Cambridge University Press, 2002).
    2. 2)
      • 2. Brekken, T.: ‘On model predictive control for point absorber wave energy converters’. Proc. of IEEE Trondheim Power Tech., 2011.
    3. 3)
      • 3. Fusco, F., Ringwood, J.: ‘Hierarchical robust control of oscillating wave energy converters with uncertain dynamic’, IEEE Trans. Sustain. Energy, 2014, 5, pp. 598966.
    4. 4)
      • 4. Fusco, F., Ringwood, J.: ‘A simple and effective real-time controller for wave energy converters’, IEEE Trans. Sustain. Energy, 2014, 4, pp. 2130.
    5. 5)
      • 5. Wahyudie, A., Jama, M.A., Saeed, O., et al: ‘Robust and low computational cost controller for improving captured power in heaving wave energy converters’, J. Renew. Energy, 2015, 82, pp. 114124.
    6. 6)
      • 6. Wahyudie, A., Jama, M.A., Saeed, O.: ‘Robust hierarchical control strategy for heaving wave energy converters’. Proc. of IEEE Oceans Conference, 2015.
    7. 7)
      • 7. Jama, M.A., Noura, H., Wahyudie, A., et al: ‘Enhancing the performance of heaving wave energy converters using model-free control approach’, J. Renew. Energy’, 2015, 83, pp. 931941.
    8. 8)
      • 8. Jaen, A., Andrade, D., Santana, A.: ‘Increasing the efficiency of the passive loading strategy for wave energy conversion’, J. Renew. Sustain. Energy, 2013, 5, p. 053132.
    9. 9)
      • 9. Schoen, M., Hals, J., Moan, T.: ‘Wave prediction and robust control of heaving wave energy devices for irregular waves’, IEEE Trans. Sustain. Energy, 2011, 26, pp. 627638.
    10. 10)
      • 10. Jama, M., Wahyudie, A., Assi, A., et al: ‘An intelligent fuzzy logic controller for maximum power capture of point absorbers’, Energies, 2014, 7, pp. 40334053.
    11. 11)
      • 11. Amon, E., Brekken, T., Schacher, A.: ‘Maximum power point tracking for ocean wave energy conversion’, IEEE Trans. Ind. Appl., 2012, 48, pp. 10791086.
    12. 12)
      • 12. Andrade, D., Jaen, A., Santana, A.: ‘Considering linear generator copper losses on model predictive control of a point absorber wave energy converter’, J. Energy Convers. Manage., 2014, 78, pp. 173183.
    13. 13)
      • 13. Richter, M., Magana, M., Sawodny, O., et al: ‘Nonlinear model predictive control of a point absorber wave energy converter’, IEEE Trans. Sustain. Energy, 2013, 4, pp. 118126.
    14. 14)
      • 14. Falcao, O.: ‘Wave energy utilization: a review of the technologies’, J. Renew. Sustain. Energy Rev., 2010, 14, pp. 899918.
    15. 15)
      • 15. Taghipoura, R., Pereza, T., Moan, T.: ‘Hybrid frequency-time domain for dynamic response analysis of marine structures’, J. Ocean Eng., 2008, 4, pp. 685705.
    16. 16)
      • 16. ‘User Manual’: ‘Wamit Inc’. Available at
    17. 17)
      • 17. Sul, S.: ‘Control of electric machine drive systems’ (Wiley, 2011).
    18. 18)
      • 18. Feng, W., Zhang, X., Ju, P., et al: ‘Modelling and control of aws-based wave energy convertion system integrated into grid’, IEEE Trans. Power Syst., 2008, 23, pp. 196204.
    19. 19)
      • 19. Doyle, J., Francis, B., Tannenbaum, A.: ‘Feedback control theory’ (Macmillan Publishing Co., 1990).
    20. 20)
      • 20. Ho, M., Lin, C.: ‘PID controller design for robust performance’, IEEE Trans. Autom. Control, 2003, 48, (8), pp. 14041409.
    21. 21)
      • 21. Tucker, M.: ‘Waves in ocean engineering: measurement, analysis, and interpretation’ (Ellis Horwood LTD, 1991).
    22. 22)
      • 22. Skogestad, S., Postlethwaite, I.: ‘Multivariable feedback control: analysis and design’ (Wiley, 2005).
    23. 23)
      • 23. ‘Multi-parametric toolbox 3’, ETH Zurich. Available at
    24. 24)
      • 24. Kumar, V., Kumar, K.: ‘Spectral characteristic of high shallow water waves’, J. Ocean Eng., 2008, 35, pp. 900911.

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