Experimental and Numerical Study on Point Absorber Type Wave Energy Converter With Linear Generator

This paper addresses experimental and numerical validation of power output efficiency about an approximate complex-conjugate control with considering the copper loss (ACL) method. A bottom-fixed point absorber type wave energy convertor (WEC) model was used for the experiments carried out at National Maritime Research Institute, Japan (NMRI). In order to model a power take-off (PTO) system constructed by a permanent magnet linear generator (PMLG), a liner shaft motor (LSM) was used for the model test. To investigate characteristics of the ACL method, the resistive load control (RLC) method and approximate complex-conjugate control (ACC) method were also tested by the WEC model. A simulation code based on WEC-Sim (Wave Energy Converter SIMulator) v2.0 written by MATLAB/Simulink, which is developed by collaboration works between the National Renewable Energy Laboratory (NREL) and Sandia National Laboratories (Sandia), was used for the validation. The simulated results in regular waves have good agreement with measured ones in terms of the float heave motion, the vertical force and the control input force. Through the experiments and numerical simulations in regular waves, the ACL method has advantages in high power production compared with the RLC and the ACC methods for the WEC model. In addition, the power output characteristics of the ACL method in irregular waves were checked experimentally and numerically.