Performance of optimally tuned arrays of heaving point absorbers

Abstract

Arrays of heaving point absorbers in various arrangements are analysed to study their performance in terms of the amount of power absorption and the power uniformity among floaters. The numerical simulations for the determination of hydrodynamic coefficients and forces are obtained using a Boundary Element Method (BEM) code. A linear external damping coefficient is applied to enable power extraction and a supplementary mass is introduced to tune the floater to the incoming wave conditions. Each floater is assumed to have its own identical power take-off system. The external damping coefficient and the supplementary mass are individually optimized for each floater to maximize the total power absorption by the array. This optimization is implemented with slamming, stroke and force restrictions imposed on the floater motion by SQP method. Attention is also paid to the performance of each floater in various arrangements. Furthermore, the effect of incoming wave headings is taken into account. To quantify the performance, q-factor and coefficient of variation are compared for each array for a range of sea states. This present study will be helpful in the understanding and design of the best possible configuration of arrays of heaving point absorber WEC systems to extract more wave power and achieve better power recovery uniformity.