A Performance Comparison Between Hydraulic and Electric Energy Storage Systems for Wave Energy Applications

Two energy storage systems were considered and compared numerically for a wave energy converter (WEe) con-nected to the power grid. The first system is an Electric Energy Storage System (EESS), and the second system is a Hydraulic Energy Storge System (HESS). A wave-to-wire numerical model of the WEC was developed considering both energy storage systems. The numerical model includes an admittance model of a point absorber, a detailed model of the PTO system, and a numerical model of the electric generator and power converter. For the EESS, the battery is connected to the DC link of the power converter, and a control algorithm is applied based on the desired value of active power generated. For the HESS, the hydraulic system rectifies the motion of the WEC for the connection to the electric generator, and a hydraulic accumulator is used as the energy storage device. The performance of both systems was compared numerically.