Wave Power Absorption as a Function of Water Level and Wave Height: Theory and Experiment

This paper investigates the sensitivity of a wave power system to variations in still water levels and significant wave heights. The system consists of a floating point absorber connected to a linear generator on the seabed. Changing still water levels are expected to affect the power absorption, since they will displace the equilibrium position for the generator translator. Similarly, changing significant wave heights will affect the rate at which the translator leaves the stator. Both these effects will in some cases result in a smaller active area of the stator. A theoretical expression to describe this effect is derived, and compared to measured experimental values for the wave energy converter L1 at the Lysekil research site. During the time of measurements, the still water levels at the site were in the range of [-0.70 m, +0.46 m ], and the significant wave heights in the range of [0 m, 2.7 m]. The experimental values exhibit characteristics similar to those of the theoretical expression, especially with changing significant wave heights.