Optimization of heterogeneous arrays of wave energy converters

Abstract

Optimizing the layout of devices in an array of wave energy converters (WECs) is one of the core aspects of WEC array design. More often than not, WEC arrays are designed to contain identical devices. However, to further improve power generation, this paper investigates how devices of varying dimensions can affect the overall performance of the array; the array containing devices of different sizes is referred to as a heterogeneous array in this work. The heterogeneity is achieved by varying the radius and draught of cylindrical buoys. We measured the performance of the heterogeneous array against the homogeneous array containing the same number of devices in an identical layout, assuming the summation of volumes of all devices is the same for both the heterogeneous and the homogeneous arrays. The power from the array is computed using a time-domain array dynamic model and an optimal constrained control. The hydrodynamic coefficients used as input in the dynamic model are computed using a semi-analytical method to enable computationally efficient optimization. The optimization was performed using a genetic algorithm. Arrays of 3, 5, and 7 devices are presented in this paper. For the tested wave conditions, it was found that in some wave conditions a heterogeneous array can achieve a performance improvement of up to 40% over the corresponding homogeneous array.