Estimation and Forecasting of Excitation Force for Arrays of Wave Energy Devices

To maximize energy conversion, real-time control of a wave energy converter (WEC) requires knowledge of the present and future excitation force (Fₑₓ) acting on the device, which is a nonmeasurable quantity. The problem ofestimationandforecastingofFₑₓbecomes more challenging when arrays of WECs are considered, due to the hydrodynamic interactions in the array. In this paper, a globalFₑₓestimator for a complete WEC array is developed and compared to a set of independent estimators, which utilize information local only to each device. A significant question is whether the array of measurements is sufficient to compensate for the greater complexity of the wave field, compared to the isolated body case. The paper shows that the global estimator is always more accurate than the independent estimator, improving up to45%the estimation accuracy of the independent estimator. Regarding prediction, two differentFₑₓforecasters for a WEC array are compared: a global forecaster, utilizingFₑₓestimates from the full set of array devices, and an independent forecaster, utilizing only a localFₑₓestimate. We demonstrate that the global forecaster achieves more accurate results, not only compared to the independent forecaster, but also compared to the isolated body case.