Design and Analysis of a Novel Wave Energy Converter With a Tension Leg Platform and Oscillating Proof Masses

Abstract

A design of novel wave energy converter with an oscillating proof mass and an electromagnetic power takeoff mechanism was considered. The wave energy converter has two parts, a tension leg platform connected by tether lines to the sea floor and inside of it, proof mass oscillators with motions which are coupled to those of the tension leg platform. In order to simplify the analysis, the system was constrained to only oscillate in the direction of surge. Complex hydrodynamic forces caused by ocean waves will excite the system and the surge motion of the proof mass relative to the tension leg platform will generate power via the electromagnetic power takeoff mechanism. First a model of the system with a linear restoring force exerted on the proof mass is analyzed using linear theory. Following the development of the linear theory, a more complex model with a nonlinear restoring force was considered. Using both a frequency-domain approach and a time-domain simulation, the average power of these systems were calculated. To further maximize power, a control circuit and control law are introduced which increase the average power by multiple factors. By introducing nonlinear restoring force and a control law, the performance of the system was shown to be further improved.