Abstract
To reduce the prohibitive costs of full-scale field testing, this paper presents a hardware-in-the-loop (HIL) emulation of the Wells turbine installed in the oscillating water column (OWC) wave power plant at Mutriku. The work investigates the use of real-time HIL techniques to provide a replicable, cost-effective platform for performance assessment, and PTO and control design. The experimental setup advances the state of the art by incorporating a real-gas thermodynamic formulation in the chamber model, enabled by in-situ measurements of the time-varying thermodynamic properties of the air volume. Using the HIL architecture, a comprehensive experimental campaign is conducted over a wide range of operating conditions. The flexibility of the real-time numerical model allows virtual implementation of alternative valve configurations and evaluation of different control strategies. The hydrodynamic response is characterised, revealing a strict linear relationship between chamber pressure and flow rate during Wells turbine application. A comparative evaluation of the performance of the system is presented under the chosen configurations and control strategies. The study identifies optimal operating conditions and underscores the critical trade-off between maximising power output and maintaining safe operation for economic viability. On the thermodynamic side, the results quantify the validity domain of the ideal-gas assumption. Discrepancies between ideal and real gas models become significant for large-amplitude oscillations.