Wave energy converters in array configurations—Influence of interaction effects on the power performance and fatigue of mooring lines

Journal article, 2020

In an array system of wave energy converters (WECs), hydrodynamic interactions between the WECs occur through the absorption, radiation, and diffraction of waves. The main objective of this study was to analyse hydrodynamic interactions between floating point-absorbing WECs and the influence of this interaction on the power performance and fatigue life of the WECs’ mooring lines. The hydrodynamic and structural response of the WEC systems were analysed using primarily potential flow theory, Morison equation, and continuum mechanics theory. Four 2-WEC models and two 10-WEC models were studied, among which different separating distances and mooring configurations were considered. The models were simulated for various environmental loading conditions. The results from each simulation were evaluated in terms of the power performance of each WEC, accumulated fatigue damage in each mooring line, and the levelised cost of energy (LCoE). The hydrodynamic interactions show a larger impact on the ten-WEC simulation models. In the simulations using the ten-WEC models accounting for hydrodynamic interactions, the fatigue damage in the mooring lines is varied at an average of 15% and up to an order of magnitude difference. A similar comparison for power performance showed an approximate 10% difference in the results. The LCoE calculation of the 10-WEC array system showed LCoE values ranging from -40% to +200% relative to the simulations that did not consider hydrodynamic interaction effects. Comparatively, the LCoE calculation of the 2-WEC model was either reduced by 17% or increased by 23% when the hydrodynamic interaction was included in the simulation model.