Hydrodynamic Control of Wave Energy Devices

Abstract

With this self-contained and comprehensive text, students and researchers will gain a detailed understanding of the fundamental aspects of the hydrodynamic control of wave energy converters. Such control is necessary to maximise energy capture for a given device configuration and plays a major role in efforts to make wave energy economic. Covering a wide range of disciplines, the reader is taken from the mathematical and technical fundamentals, through the main pillars of wave energy hydrodynamic control, right through to state-of-the-art algorithms for hydrodynamic control. The various operating principles of wave energy converters are exposed and the unique aspects of the hydrodynamic control problem highlighted, with a variety of potential solutions discussed. Supporting material on wave forecasting and the interaction of the hydrodynamic control problem with other aspects of wave energy device optimisation, such as device geometry optimisation and optimal device array layout, is also provided.

Adaptive Control of a Wave Energy Converter

“…2) Test 2: The resulting parameter adaptation due to the doubling of the hydrodynamic radiation force in the linear simulation is illustrated in Fig 9-(a), which plots the evolution of the first three diagonal parameter values of the N matrix. Fig 9-(a) shows that the parameters N(1, 1), N(2, 2) and N (3,3), which relate to the hydrodynamic radiation, converge to values approximately double their initial values, as might be expected. The effect of the adaptation of all the parameters in the N matrix is demonstrated in Fig 9-(b), which plots the actual simulated radiation force over a control horizon, and the linear control model approximation to this at the 15 collocation points, for both the initial and the adapted control models.…”

“…This is consistent with the findings in [18], where both the radiation and added mass values identified from CFD NWT experiments were seen to increase relative to those identified from BEM data. The evolution of N (2,9), N(2, 10) and N (3,10) are also plotted in Fig. 8, showing an increase in the parameter values identified from the CFD simulation, and little change to those identified from the linear simulation.…”

“…Fig. 8 plots the evolution of the first three diagonal entries, M(1, 1), M(2, 2) and M (3,3), showing a decrease in the parameter values identified from the CFD simulation. A decrease in the adaptive model representation of S h makes sense physically, considering S h for the sphere is maximal at equilibrium, and the adaptive model parameters therefore update to a linear average of the reduced S h values while the sphere is away from equilibrium.…”

Wave Excitation Force Estimation for Wave Energy Converters of the Point-Absorber Type

“…Several studies have shown that one of the key aspects for maximizing the energy yield of many WECs is the control of the dynamic response of the device to wave conditions, also defined as hydrodynamic control [1]. More precisely, we consider here the response control of the WEC captor, or primary converter, whose task is to transfer energy from wave to oscillating body, via the power-take off (PTO) system, responsible of a further energy conversion, generally to electricity.…”

Dominant wave frequency and amplitude estimation for adaptive control of wave energy converters

“…1 which provides a simplified representation of a heaving-buoy wave energy converter). The reader can refer to [1] for an extended definition of primary and secondary converters. Latching control, model predictive control (MPC) and PID control are examples of implementable WEC control strategies [2].…”