The paper presents a time domain model of a heaving buoy wave-energy converter and investigates the tuning problem in irregular seas. The tuning issue is addressed by employing both fixed (passive) and adaptive (active) power-take-off settings. The fixed power-take-off tuning approach includes models based on tuning the device natural frequency to either the energy frequency or peak frequency of the sea-state or a weighted average of several peak frequencies. The adaptive tuning approaches employ a sliding discrete Fourier transform frequency analysis, or a time-series analysis of the measured wave elevation and device velocity to estimate a localized dominant wave frequency and hence calculate power-take-off settings. The paper presents details of these tuning techniques by discussing issues related to the modelling, simulation, and predicted power captures for each method. A comparative study of each method along with practical implications of the results and recommendations are also presented.
The paper compares techniques for adaptive tuning of a heaving-buoy wave energy converter to provide the best possible power capture from an irregular sea. It is clear, as for output no 2 above, that such techniques will be essential for economic capture of wave energy by point-absorber collectors. The paper demonstrates that an active controller gives significantly better performance than a passive one - this finding is very likely to be taken up in practical point-absorber wave-energy collectors. RAE_import_type : Journal article RAE_uoa_type : General Engineering
