Electric Energy Maximization for Oscillating Water Column Wave Energy Systems Using a Receding-Horizon Pseudospectral Control Approach

Abstract

Among the various wave energy technologies, oscillating water columns (OWCs) have shown some of the greatest promise, due to their simplicity of operation and possibility for shore mounting, with consequent ease of access and integration with other infrastructure, such as breakwaters. To minimize the levelized cost of energy, OWC energy capture must be maximized. To date, most focus has been on maximizing air turbine efficiency, while neglecting other aspects of the system. This paper presents an integrated wave-to-wire optimal control approach, considering the OWC hydrodynamics, turbine characteristics, and generator. The approach is based on a receding-horizon pseudospectral formulation, which transcribes the continuous-time optimal control problem into a finite-dimensional nonlinear program. The results show optimal exploitation of the hydrodynamic, aerodynamic, and electric subsystem efficiency characteristics, surpassing the electric energy production available through a specific focus on turbine efficiency.