Abstract
Premature failure of mooring lines due to fatigue damage would significantly degrade the economic viability of a wave energy converter (WEC). Methods to reduce fatigue loading are therefore of interest. Here this is achieved through modification of the power take-off (PTO) control. An approximate velocity tracking (AVT) control strategy is implemented with a linear quadratic regulator (LQR) design method using differential weighting of system states. This allows balancing of power production against platform motion and, therefore, mooring loads. It is demonstrated that the controller can be tuned to capture similar mean power to an optimally tuned, passively damped system while significantly reducing mooring line cyclic loading. The relative accumulated fatigue damage in the most heavily loaded mooring lines is found