Effects of mooring failure on the dynamic behavior of the power capture platforms

Abstract

In recent years, for enhancing the ocean energy capture, it has been prevail to combine multiple wave energy converters (WECs) with the floating platforms. A power capture platform concepts is proposed in this paper based on the point-absorber WEC array and the SPIC semi-submersible platform. The present study conducts the time-domain dynamic analysis on the performance of the power capture platforms with mooring failure. After the validation of the numerical models, ANSYS-AQWA is employed to investigate the platform motion response, the remaining mooring lines' tension response, and the WEC array's power output. The results show that the platform motion and the remaining mooring lines' tension appear significant transient overshoots after mooring failure. The mean motion response of the platform increases because of the reduction of mooring stiffness. Meanwhile, the energy distribution of the platform slow-drift and roll motions at the low-frequency region increases as well. Moreover, the mooring line tension adjacent to the failed mooring line increases significantly, while that of other mooring lines decreases. Notably, mooring failure has slight effects on the WEC array's energy conversion performance, and the total absorbed power among Model 2 is more than that among Model 1. These important findings provide some insights into the design of power capture platforms. Moreover, to ensure the floating system stable and reliable, the effects of mooring failure and the resulting changes should be evaluated in advance.