A wave-to-wire chain modeling and command for a direct drive wave energy converter

Power quality is an important issue for wave energy developers, as the wave energy converters output power profile presents a lot of fluctuations due to the oscillatory nature of the waves. In order to emulate an operating direct drive wave energy converter, study power quality improvement and test different control strategies, a wave-to-wire model has been developed. Although control study for wave energy converters is often limited to the hydrodynamic control, this paper addresses the dynamic modeling of all the conversion stages, from the waves to the electric network. First, the wave energy converter used for this study is presented and a model for the electric parts is proposed (including a back-to-back converter). Then, control strategies are discussed, in order to regulate the generator electromagnetic torque, the DC-link voltage and the grid voltages and reactive power. Simulation results considering these control strategies are presented in the last part.