Random Wave Energy Conversion of a Spar–Floater System via the Inerter Pendulum Vibration Absorber Integration

Abstract

Incorporating wave energy converters (WECs) into existing oceanographic instrument systems and offshore floating platforms can not only enhance the performance of these applications but reduce operational expenses. This article studies a system integrating a floater WEC with a floating spar platform via the inerter pendulum vibration absorber with a power take-off (IPVA-PTO) mechanism, with a focus on random wave excitation. Experiments and simulations performed on a simplified system in which the WEC is held fixed and radiation damping is absent reveal that the power spectral density (PSD) of the system consists of odd-order superharmonics when the peak frequency of wave excitation is equal to the natural frequency of the system. It is found that the odd-order superharmonics are created by the IPVA and have a strong correlation with an enhancement in power output. Simulations without the aforementioned simplifications confirm the odd-order superharmonics and the correlation, and demonstrate an improvement in the capture width ratio (CWR) of 161.4% at resonance without compromising the response amplitude operator (RAO) of the spar, in comparison with a linear benchmark with optimal electrical damping.