Control parametric resonance of wave energy conversion systems

Project Information

CONPARA

Grant agreement ID: 841388

DOI

10.3030/841388

Project closed

EC signature date 11 April 2019

Start date 3 June 2019

End date 2 June 2021

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 196 590,72

EU contribution

€ 196 590,72

Coordinated by

NATIONAL UNIVERSITY OF IRELAND MAYNOOTH
Ireland

Periodic Reporting for period 1 - CONPARA (Control parametric resonance of wave energy conversion systems)

Reporting period: 2019-06-03 to 2021-06-02

Summary of the context and overall objectives of the project

This Marie Skłodowska Curie Action (MSCA) project, entitled “Control parametric resonance of wave energy conversion systems (CONPARA)”, looks at how parametric resonance occurs in pitch and roll modes of wave energy converters (WECs), and how WECs make use of parametric resonance to improve its performance. The research questions are: (1) how to model parametric resonance in an accurate and efficient manner, (2) how to qualify the energy transfer form one degree of freedom (DoF) to another, and (3) how to set on or set off the occurrence of parametric resonance. Those topics are important because parametric resonance has been frequently observed in WECs as an unexpected nonlinear phenomenon. Not only is there widespread lack of understanding the nonlinear dynamics and energy transfer mechanism caused by parametric resonance, but open questions also have been identified in modelling, detecting, predicting and control of parametric resonance.
Among various renewable energy resources, wave energy has a great potential in providing a low-carbon energy society, (1) to fulfil the Sustainable Development Goal (SDG) of affordable and clean energy defined by the United Nations (UN), and (2) to achieve the EU 2030 Climate & Energy Framework objectives. Currently, WEC technology has not been commercially applied, mainly due to its high levelised cost of energy (LCoE). However, the LCoE can be reduced significantly by the novel control system developed in this project, via designs of (1) WECs to exploit parametric resonance, and (2) multi-DoF control and power take-off (PTO) systems. With a significantly reduction in LCoE, commercial operation of WEC farms can directly contribute to UN’s Carbon Neutral goal in 2050.
The project objectives are dedicated to: (1) identifying a high-fidelity and computation-efficient model to represent WEC parametric resonance, (2) developing novel power take-off mechanism and corresponding control methods to improve WEC efficiency by utilising parametric resonance, (c) prototyping a scaled down WEC rig for tank testing. A parallel goal of this MSCA project is to foster the career development of the individual fellow from an early year researcher to an independent investigator.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Research work was conducted via 6 work packages (WPs). (1) WP1 comprised 2 overall project management tasks, including weekly meeting with the host supervisor and progress panel meeting every 6 months. In it, the Fellow identified a career development plan (CDP), ensured the project progress, and participated in training activities and two-way transfer of knowledge. (2) WP2 was dedicated to dissemination and communication. In it, the Fellow organised 1 conference session, 2 workshops and 1 special issue, participated 5 conferences, 2 workshops, 89 seminars, and 1 video, and updated 1 website and 120 social media posts. (3) WP3 involved training and transfer of knowledges. The Fellow participated in 6 training courses, presented in 9 seminars, attended 89 seminars, supervised 3 internship projects, interviewed 12 candidates for post-doctoral research fellow positions. (4) In WP4, the Fellow focused on the modelling of parametric resonance. A generic nonlinear hydrodynamic model was derived, with an ability to articulate parametric coupling between individual degrees of freedom. CFD was used to verify the mathematical model, parametric analysis was conducted to investigate rich and complex nonlinear dynamics caused by parametric resonance. (5) In WP5, control and PTO mechanism were investigated based on the mathematical model, passive and reactive control strategies were studied for maximizing WEC power production. A PTO mechanism was designed to harvest energy from the multi-DoF motions. (6) WP6 was dedicated to prototyping scaled down WEC model and the Fellow developed a WEC rig for testing.
Results of this MSCA project are reported in: (1) forthcoming papers on control parametric resonance vibro-impact PTO mechanism, (2) forthcoming papers on energy transfer of parametric resonance for wave energy conversion, (3) forthcoming papers on effect of nonlinear hydrodynamic modelling on WEC geometric optimization, (4) papers about the modelling of vibro-impact PTO mechanism, and (5) a systematic survey of geometric optimization of WEC systems. The modelling methods, PTO design and control approaches developed during this MSCA project will inform and enhance dozens of publications in the coming years, in addition to the ones produced and published during the fellowship itself.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

This MSCA has pushed the frontiers of understanding and modelling of parametric resonance in wave energy sector forward in numerous ways. The specific foci the Fellow spearheaded have shed new light onto the energy transfer between different DoFs and PTO design to set on or off parametric resonance according to sea states. When parametric resonance occurs, the operation modes are coupled mutually. The occurrence of parametric is sensitive to initial conditions, and there co-exist multiple attractors. This initials the possibility of a high-level supervision control system, to switch the system dynamics from one attractor to another, for triggering or suppressing parametric resonance. Thus, pitching and rolling WECs can make use of parametric resonance to absorber more power, as power in heave can be transferred to pitch and roll. Alternatively, it is also possible for heaving devices to spill power to roll/pitch motion via parametric resonance, especially when the heave motion exceeds the stroke constraints.
This MSCA allowed the Fellow to develop agility with many different research methodologies and promote best practices to the larger wave energy community. The Fellow’s modelling methods were adopted to WEC modelling tasks organised by the Ocean Energy Systems in the International Energy Agency. The modelling methods developed by the Fellow were also integrated to a couple of ongoing projects leading by the hosting supervisor Prof. John Ringwood, by providing high-fidelity and computation-effective models for WEC optimisation and real-time control implementation. These projects aim to reduce the LCoE of wave energy technology to provide low-cost and carbon-free electricity for the society, for fulfilling the UN’s SDG of affordable and clean energy. Through the Fellow’s research on modelling and control of WEC parametric resonance, valuable new understandings are emerging related to improving WEC energy production in moderate sea states and survivability under extreme waves.
Socio-economic impact anticipated from this MSCA project is increased and improved. The foci on nonlinear WEC modelling were well shared among WEC researchers, engineers, and technicians. Policy makers and investigators were more convinced on reducing the LCoE of wave energy technology with improved support. More undergraduates expressed their concerns and interests in renewable energy technology. A final overarching impact is the enhanced public understanding in wave energy potential in achieving UN’s Carbon Neutral goal by 2050.

Vibro-impact wave energy converter to ultilise paramentric resonance