Optimal mooring configuration of a floating two-buoy wave energy converter

A fully coupled dynamic interaction framework, including time-domain hydrodynamic simulation of nonlinear dynamic response and global-local hybrid optimization, is applied to optimize key catenary mooring parameters. The numerical model comprises boundary-element hydrodynamic and lumped-mass mooring modules which are bidirectionally coupled through a force-motion boundary condition. The coupled numerical framework is validated against experimental data from a 1:5 scale floating two-buoy wave energy converter (WEC). By considering the sensitivity and coupling relationship between different mooring parameters, the solution spaces of the mass and length of the catenary chain are determined for the optimization model. Ten hybrid optimization techniques are considered, involving a global algorithm (selected from Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Simulated Annealing (SA), MultiStart and GlobalSearch) combined with a local algorithm (selected from the Interior-Point Method (IPM) and Sequential Quadratic Programming (SQP)). It is found that GA has good global search capability, high predictive accuracy, and is particularly well suited to solving optimization problems encountered in the design of complex mooring systems. The motion and tension force experienced by the optimal configuration are used to assess the optimal response performance of the two-body WEC. This study provides guidance for the design and selection of an efficient mooring system for a floating two-buoy WEC.