Parametric Optimization of Dynamic Power Cable Configurations

Abstract

Floating offshore wind turbines offer opportunities to harvest wind energy at deep-water locations, where the construction of fixed-base turbines is infeasible. The dynamic power cables, which interconnect turbines and transport the generated electricity, are under large dynamic stresses due to the environmental loads and the motion of the floating platform. Limited knowledge about the structural behaviour of these cables is available, which is why there is need for new analysis and design methods. This MSc thesis presents a method for the preliminary design optimization of the dynamic power cable configuration. A parametric model of a dynamic power cable is built in the commercial software package OrcaFlex, from which motions, loads and fatigue on the cable can be calculated. Following that, a radial basis function model-based optimization algorithm is applied to find the optimal cable configuration for an arbitrary environmental scenario. The key performance indicator here is fatigue damage on the copper conductor, which is expected to be critical due to the cyclic loading on the cable and the poor mechanical properties of copper. Experiments are carried out to test the optimization model’s validity in terms of convergence, robustness and efficiency. The final method is capable of consistently finding a near-optimal dynamic power cable configuration design within reasonable time. Additionally, findings are presented about the fatigue behaviour of the DPC, what causes the fatigue damage and how to mitigate the effects.