SDWED: WAVE TO WIRE MODELLING

Transcription

1 SDWED: WAVE TO WIRE MODELLING Peter Frigaard Department of Civil Engineering,Aalborg University Denmark Copenhagen August 30th

2 TRADITIONAL DEFINITION A wave to wire model is a numerical model (or a suit of numerical models) used to evaluate the electrical power generated by a given wave energy converter from given wave conditions. Copenhagen August 30th

3 OUR DEFINITION A wave to wire model is a numerical model (or a suit of numerical models) used to evaluate the forces acting on a wave energy converter, the stresses in the structure, the behavior and the electrical power generated by a given wave energy converter from given wave conditions. Copenhagen August 30th

4 WHAT WILL WE USE THE MODEL FOR? Analyze/optimize behavior of system (Wave energy converter) Efficiency Yearly power production Dimension of structure (Cost) Cost of energy Other environmental effects Copenhagen August 30th

5 PROBLEM Everything depends on everything. Coupled problem Wave Forces Mooring Structural design Control Strategy Power production Copenhagen August 30th

6 Example 1: Wave Dragon - A Slack Moored Wave Energy Device of the Overtopping Type What if we cange the moorings? / Control Strategy? 1:50 Model in Wave Tank Copenhagen August 30th

7 Copenhagen August 30th

8 Example 1: Wave STAR - A Multipoint absorber What if we cange the Control Strategy? Copenhagen August 30th 2010

9 AGAIN THE PROBLEM Everything depends on everything. System must be solved in one go. Traditional strategy: We use linear subsystems or model subsystems using linear models. Change from components to system approach. Copenhagen August 30th

10 Design considerations The ratio between design forces and operationel forces are for Wave Energy devices typically 2-30, where they for wind turbines are 1-2. As many forces as possible shall be taken as internal forces, i.e. Pelamis where only 2. order drift forces are taken by the moorings. The reference point (foundation) shall not act against all forces. Copenhagen August 30th

11 SSG Project Wave Forces Model tests for Gorliz, Spain project Copenhagen August 30th

12 Resonance systems In t Test from Griet De Backer, Ghent and my holiday Copenhagen August 30th

13 In the range from normal wave to survival condition it might be preferred to use different numerical tools, and in addition to power production also evaluates design loads, fatigue elements (WP5), control and failure aspects associated with the wave energy converter. Copenhagen August 30th

14 Some systems might benefit or even need estimations of the future. Copenhagen August 30th

15 For Each Floater (in Real Time) we: Estimate the Next Wave. Difficult because Waves are Dispersve and 3D Estimate Force on Floater. Wamit-type Multibody Software (Depend on Control Strategy) Select Gear for the Power Take-Off for Each Floater Copenhagen August 30th

16 Average Power [kw] DEPARTMENT OF CIVIL ENGINEERING Power and Efficiency Hs [m] Produced Estimated Hydraulic Copenhagen August 30th 2010

17 Copenhagen August 30th 2010

18 What do we have today on wave to wire models? Basically nothing on system level. A lot on component level. Some device depended system models. What to do: Define interfaces Copenhagen August 30th

19 To repeat We need models of systems We need non linear models of components Real time systems -> approximations Focus on structure more than power production We have to decrease design loads Copenhagen August 30th

20 Thank You. Copenhagen August 30th