Estimating the loads and energy yield of arrays of wave energy converters under realistic seas

Abstract

Estimates regarding the assessment of the energy absorption characteristics of an array of wave energy converters (also referred to as a wave farm) are presented. Regular and irregular waves are used as input in a frequency-domain hydrodynamic model, which allows iterations in the array layout and farm control strategy. Under such an approach each array element can be controlled independently while keeping the design objective (maximisation of the wave farm energy yield). The distribution of power take-off (PTO) loading on the various array elements, as induced by the incoming sea, is also investigated. The approach is verified by comparing the estimates with results from a semi-analytic method developed at the University of Oxford. The overall objective of the study is to quantify the influence of the array layout and farm control in the performance of a wave farm under the action of irregular waves. The results show that the energy yield and the PTO loads are affected by such factors; hence these can be seen as key design drivers in order to reduce the uncertainty and thus the cost of energy when planning a wave farm. Further studies may address additional constraints, either technical or economical. This study is expected to contribute to the development of specific modules of a design optimisation tool for wave farms, and extends the findings originally presented at the Eighth European Wave and Tidal Energy Conference.