Abstract
The paper presents a detailed analysis of the dynamics and control of air turbines and electrical generators in oscillating-water-columns (OWCs). The aim is to explain the performance of an OWC device based on the physical behaviour of each system component. The Mutriku wave power plant was chosen as the test case. The power plant is a breakwater located in the Bay of Biscay, in Basque Country, Spain. The contributions of the work are: i) development of a hydrodynamic model of the power plant in the frequency domain; ii) implementation of a non-linear time-domain wave-to-wire model; iii) real-valued implementation of the Prony method for the computation of the wave-radiation force; iv) a detailed generator model based on experimental data to assess the influence of the generator efficiency on the power take-off performance; v) a critical performance comparison of the Wells and biradial turbines; vi) a sensitivity analysis of the control parameters of the turbine/generator set; and vii) an explanation of the comparative performance of both turbines based on statistical data. The turbine performance curves were taken from developers’ published experimental data. The results were obtained with a simplified model of the wave climate off the Mutriku test site comprising 14 sea states.