1. EWTEC 2017: Experimental assessment of an innovative concept for managing mooring load
INNOSEA
Rémy PASCAL

2. LAMWEC project consortium:
The LAMWEC project seeks to develop and test a 200kW Laminaria wave energy converter (WEC), through complementary research and test activities aimed at defining all the design improvements needed for upscaling the prototype tested in the North Sea.
Main deliverables:
Design and build of a 200kW Laminaria WEC incorporating a scaled up version of the power take-off (PTO) and storm protection system
Development of a new anchor design suitable for a range of seabed configurations
The development of a mooring and pulley system for the 11.8 metre diameter (270 tonne) device that will support the innovative storm protection system, PTO, and frame.
consortium:
EWTEC 2017 – Experimental assessment of an innovative concept for managing mooring load

3. LAMWEC project Role of INNOSEA in the project
Establish a numerical model of the device in INWAWE
Performance estimation
Optimisation
Support load estimation
Specify PTO inputs
Manage the tank testing campaign of March 2016
Establish test plan
Manage relation with the facility
Assist Laminaria during tests
Post-process the data
EWTEC 2017 – Experimental assessment of an innovative concept for managing mooring load

4. LAMWEC tank test Objectives of the tests
Proof of concept for the submergence storm protection
Proof of concept for the PTO overdrive
Mooring load estimation in a range of conditions (EMEC target test site
Base performance estimation
Provide data for numerical model validation
EWTEC 2017 – Experimental assessment of an innovative concept for managing mooring load

5. LAMWEC tank test Objectives of the tests Context
Proof of concept for the submergence storm protection
Proof of concept for the PTO overdrive
Mooring load estimation in a range of conditions (EMEC target test site
Base performance estimation
Provide data for numerical model validation
Context
Tests conducted at the COAST lab
Full use of the moving floor
Underwater Qualysis
Support of Peter Arber during the tests was fully appreciated
Model provided by Laminaria
EWTEC 2017 – Experimental assessment of an innovative concept for managing mooring load

6. LAMWEC tank test: the concept
EWTEC 2017 – Experimental assessment of an innovative concept for managing mooring load

7. LAMWEC tank test: the concept
Mooring configuration
EWTEC 2017 – Experimental assessment of an innovative concept for managing mooring load

8. LAMWEC tank test: the concept
The theoretical PTO
Measuring the loads from the mooring lines load cells
Controlling the drum speed
Overdrive ensure that load umbalance between paired lines is “capped”
EWTEC 2017 – Experimental assessment of an innovative concept for managing mooring load

9. LAMWEC tank test: the video
Link to LAMWEC video:
EWTEC 2017 – Experimental assessment of an innovative concept for managing mooring load

10. LAMWEC tank test: focusing on the loads
The methods
Establish histograms of the loads
Smooth data
Extact maxes by finding zeros of derived signal
Decluster maxes
Establish histograms of normed occurences
EWTEC 2017 – Experimental assessment of an innovative concept for managing mooring load

11. LAMWEC tank test: focusing on the loads
The methods
Establish histograms of the loads
Smooth data
Extract maxes by finding zeros of derived signal
Decluster maxes
Establish histograms of normed occurrences
Fit Statistical distribution on histograms
Weibull_minimum distribution
3 parameters
EWTEC 2017 – Experimental assessment of an innovative concept for managing mooring load

12. LAMWEC tank test: the results
Qualitative results
Effectiveness of the overdrive mechanism
EWTEC 2017 – Experimental assessment of an innovative concept for managing mooring load

13. LAMWEC tank test: the results
Qualitative results
Effectiveness of the overdrive mechanism
Effect visible on the mooring line loads
Create some issues with fitting of distributions
EWTEC 2017 – Experimental assessment of an innovative concept for managing mooring load

14. LAMWEC tank test: the results
Quantitative results
Base statistics on the results
Show effect of submergence on dynamic loads
Decorrelation of loads with HS
EWTEC 2017 – Experimental assessment of an innovative concept for managing mooring load

15. LAMWEC tank test: the results
Quantitative results
Base statistics on the results
Full scale HS: 1.25m to 7m+
Max loads are only slighlty increasing
Possibility to further submerged device
Show effect of submergence on dynamic loads
Decorrelation of loads with HS
EWTEC 2017 – Experimental assessment of an innovative concept for managing mooring load

16. LAMWEC tank test: the results
Quantitative results
Parameters of the statistical distributions
EWTEC 2017 – Experimental assessment of an innovative concept for managing mooring load

17. LAMWEC tank test: the results
Quantitative results
Parameters of the statistical distributions
EWTEC 2017 – Experimental assessment of an innovative concept for managing mooring load

18. LAMWEC tank test: the results
Quantitative results
Parameters of the statistical distributions
Possibility to built parametric model of the mooring line loads
Great for design
EWTEC 2017 – Experimental assessment of an innovative concept for managing mooring load

19. LAMWEC tank test: Conclusion
Proof of concept
Overdrive concept proved by qualitative appreciation of the loads histogram
Manage extreme loads on moorings
Effectiveness of submergence to minimize loads proved by observing and characterising loads histograms
Manage average loads
Helps to dimension PTO
EWTEC 2017 – Experimental assessment of an innovative concept for managing mooring load

20. LAMWEC tank test: Conclusion
Proof of concept
Overdrive concept proved by qualitative appreciation of the loads histogram
Manage extreme loads on moorings
Effectiveness of submergence to minimize loads proved by observing and characterising loads histograms
Manage average loads
Helps to dimension PTO
Opportunity for future tests
No overdrive limit in PTO
PTO controlled in torque, not speed
Overlap in Hs and submergence levels
EWTEC 2017 – Experimental assessment of an innovative concept for managing mooring load