Comparison of Control Strategies for Wave Energy Converters

Abstract: The development of wave power generation has been carried out since the 1790s. The technology involves capturing the energy of the wave using an actuation mechanism and converting it into useful work. Over the years many kinds of wave energy converters have been designed with varying rates of success. Novige has redesigned the buoy to a rectangular form thereby increasing the wetted area compared to standard round buoys. The primary approach for power absorption for Novige is latching control. But, different other control strategies were also proposed. The objective of the thesis is to compare the control strategies for WEC. The idea of latching came from the necessity to align phases of excitation force and velocity. One way is to latch (keep in the same position) device until the excitation force reaches its maximum. When the excitation force and velocity of the device are aligned in phase, the condition for the maximum power absorption is met. Latchingcontrol is commonly used in WEC to increase power absorption capacity. Different approaches can be taken to implement latching control. Latching of the WEC can be adjusted based on a sea state or on the wave to wave basis that passes through the WEC. This thesis will compare the latching strategies and propose the optimal latching strategy for NoviOcean as well as propose some new approaches for motion prediction. The predicted excitation force is then compared on average absorbed power and complexity for implementation.