Optimization of nonlinear wave energy converters

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© 2018 Elsevier Ltd This paper presents an optimization approach for the nonlinear control of wave energy converters (WECs). The proposed optimization method also presents the option of optimizing the system nonlinearities, such as those due to the buoy shape, such that the harvested energy is maximized. For the sake of control design, the control force and the system optimizable nonlinear force, each is expressed as a truncated power series function of the system states. The power series coefficients in both the control and system forces are optimized. A hidden genes genetic algorithm is used for optimization. The optimized system's nonlinear force is assumed to drive the design of the WEC. The numerical test cases presented in this paper show that it is possible to attain multiple fold higher harvested energy when using nonlinear control optimization. The advantage of being able to optimize the WEC design simultaneously with the control is the potential of harvesting this multiple fold higher energy without causing large WEC motion and with less dependence on reactive power. While this paper focuses on the optimization part of the problem, the implementation of the obtained control in realtime is discussed at the end of the paper.

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Ocean Engineering