Control of offshore marine substation for grid-connection of a wave power farm

• A marine substation has been designed for grid-connection of a wave power farm.
• The control procedure for the complete grid-connection of the WECs is presented.
• The paper discusses e.g. cable resonance, safe operation, faults, harmonics and flicker.

To grid-connect an offshore wave power farm, an intermediate marine substation is suggested. As a part of the Uppsala University wave power project, a marine substation has been designed, assembled and deployed at sea. The substation is capable of connecting up to seven wave energy converters (WECs), and to transfer the power to the onshore 1 kV-grid. In this article, the control procedure for grid connection of the WECs is described step-by-step, and the practical implementations are presented. The system is designed with autonomous control and will connect or disconnect the WECs, depending on the sea state. Fault handling is taken into account, and grid power quality such as harmonic distortion and flicker are considered in the design. Experimental results are presented to verify the system functionalities.