Frequency domain modeling and analysis of a direct drive point absorber wave energy converter

Based on the linear wave theory, by assuming the power take off force (PTO) was modeled to be linear and restricting the consideration of heave motion, the equation of motion of a direct drive point absorber wave energy converter (WEC) in the frequency domain was established, and its frequency response function (FRF) was obtained. The expression of power capture width in regular and random waves were derived, the influence of buoy geometry, FRF, PTO damping coefficient and wave climate on power capture width were investigated. It is found that the smaller difference between the natural frequency and the peak frequency of the wave spectrum, the larger amplitude of the FRF, and the greater PTO damping coefficient can lead to a relatively larger power capture width.