Connection technology of HPTO type WECs and DC nano grid in island


Wave energy fluctuating a great deal endangers the security of power grid especially micro grid in island. A DC nano grid supported by batteries is proposed to smooth the output power of wave energy converters (WECs). Thus, renewable energy converters connected to DC grid is a new subject. The characteristics of WECs are very important to the connection technology of HPTO type WECs and DC nano grid. Hydraulic power take-off system (HPTO) is the core unit of the largest category of WECs, with the functions of supplying suitable damping for a WEC to absorb wave energy, and converting captured wave energy to electricity. The HPTO is divided into a hydraulic energy storage system (HESS) and a hydraulic power generation system (HPGS). A primary numerical model for the HPGS is established in this paper. Three important basic characteristics of the HPGS are deduced, which reveal how the generator load determines the HPGS rotation rate. Therefore, the connector of HPTO type WEC and DC nano grid would be an uncontrollable rectifier with high reliability, also would be a controllable power converter with high efficiency, such as interleaved boost converter-IBC. The research shows that it is very flexible to connect to DC nano grid for WECs, but bypass resistance loads are indispensable for the security of WECs.

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  1. Clement, A., McCullen, P., Falcão, A. F. O., Fiorentino, A., Gardner, F., Hammarlund, K., Lemonis, G., Lewis, T., Nielsen, K., Petroncini, S., Pontes, M. T., Schild, P., Sjöström, B. O., Sørensen, H. C. and Thorpe, T., 2002. Wave energy in Europe: Current status and perspectives, Renewable and Sustainable Energy Reviews, 6(5): 405–431.

    Article  Google Scholar 

  2. Dahbi, A., Hachemi, M., Nait-Said, N. and Nait-Said, M., 2014. Realization and control of a wind turbine connected to the grid by using PMSG, Energy Conversion and Management, 84, 346–353.

    Article  Google Scholar 

  3. Falcão, A. F. O., 2008. The Development of Wave Energy Utilisation, International Energy Agency Implementing Agreement on Ocean Energy Systems (IEA-OES), Annual Report, 30–37.

    Google Scholar 

  4. Falcão, A. F. O., 2010. Wave energy utilization: A review of the technologies, Renewable and Sustainable Energy Reviews, 14(3): 899–918.

    Article  Google Scholar 

  5. Hansen, A. H., Pedersen, H. C. and Andersen, T. O., 2014. Model based feasibility study on bidirectional check valves in wave energy converters, International Journal of Marine Energy, 5, 1–23.

    Article  Google Scholar 

  6. Henderson, R., 2006. Design, simulation, and testing of a novel hydraulic power take-off system for the Pelamis wave energy converter, Renewable Energy, 31(1): 271–283.

    Article  Google Scholar 

  7. Nielsen, K. and Plum, C., 2000. Comparison of experimental and theoretical results of the motions of a McCabe wave pump, Proceedings of the 4th European Wave Energy Conference, Aalborg, 56–62.

    Google Scholar 

  8. Rhinefrank, K., Agamloh, E. B., Jouanne, A. V., Wallace, A. K., Prudell, J., Kimble, K., Aills, J., Schmidt, E., Chan, P., Sweeny, B. and Schacher, A., 2006. Novel ocean energy permanent magnet linear generator buoy, Renewable Energy, 31(9): 1279–1298.

    Article  Google Scholar 

  9. Salter, S. H., 1974. Wave power, Nature, 249(5459): 720–724.

    Article  Google Scholar 

  10. Sheng, S. W., You, Y. G., Zhang, Y. Q., Wu, B. J. and Sun, Z. P., 2012. Research on power take-off system of floating wave power device, Journal of Mechanical Engineering, 48(24): 141–146. (in Chinese)

    Article  Google Scholar 

  11. Skretas, S. B. and Papadopoulos, D. P., 2009. Efficient design and simulation of an expandable hybrid (wind–photovoltaic) power system with MPPT and inverter input voltage regulation features in compliance with electric grid requirements, Electric Power Systems Research, 79(9): 1271–1285.

    Article  Google Scholar 

  12. Yang, Q., Li, H., Li, D., Jiang, H., Li, X. and Liu, S., 2000. Research and Development of Daguan Island 30 kW Pendulum Wave Power Station, Report of National Ocean Technology Center, Tianjin, China. (in Chinese)

    Google Scholar 

  13. You, Y. G., Sheng, S. W., Wu, B. J. and He, Y. Q., 2012. Wave energy technology in China, Philosophical Transactions of the Royal Society, 370(1959): 472–480.

    Article  Google Scholar 

  14. Zhang, D. H., Li, W., Zhao, H. T., Bao, J. W. and Lin, Y. G., 2014. Design of a hydraulic power take-off system for the wave energy device with an inverse pendulum, China Ocean Eng., 28(2): 283–292.

    Article  Google Scholar 

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Corresponding author

Correspondence to Kun-lin Wang 王坤林.

Additional information

This research was financially supported by the Natural Science Foundation of Guangdong Province (Grant No. 2015A030313717), the Chinese Ocean Renewable Energy Special Fund (Grant Nos. GHME2013ZB01, GHME2013GC01, and GHME2010GC01), and Renewable Energy Key Laboratory 2013 Annual Fund of the Academy of Sciences of China (Grant No. y407j71001).

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Wang, Kl., Tian, Lf., You, Yg. et al. Connection technology of HPTO type WECs and DC nano grid in island. China Ocean Eng 30, 581–590 (2016).

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Key words

  • wave energy converter
  • hydraulic power take-off
  • hydraulic power generation system
  • interleaved boost converter
  • nano grid