Reducing wave energy converter mooring fatigue through PTO control

Andrew J. Hillis, Charles R.P. Courtney, Annette Brask

Research output: Contribution to journalConference articlepeer-review


Premature failure of mooring lines due to fatigue damage would significantly degrade the economic viability of a wave energy converter (WEC). Methods to reduce fatigue loading are therefore of interest. Here this is achieved through modification of the power take-off (PTO) control. An approximate velocity tracking (AVT) control strategy is implemented with a linear quadratic regulator (LQR) design method using differential weighting of system states. This allows balancing of power production against platform motion and, therefore, mooring loads. It is demonstrated that the controller can be tuned to capture similar mean power to an optimally tuned, passively damped system while significantly reducing mooring line cyclic loading. The relative accumulated fatigue damage in the most heavily loaded mooring lines is found be reduced by 72% as a result of using the AVT strategy.

Original languageEnglish
Pages (from-to)1968-1-1968-6
Number of pages6
JournalProceedings of the European Wave and Tidal Energy Conference
Publication statusPublished - 9 Sept 2021
Event14th European Wave and Tidal Energy Conference, EWTEC 2021 - Virtual, Online
Duration: 5 Sept 20219 Sept 2021


  • Active control
  • Fatigue
  • Mooring load
  • Power take off
  • Submerged Wave Energy Converter

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Renewable Energy, Sustainability and the Environment
  • Ocean Engineering
  • Water Science and Technology


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