Abstract
The implementation of an all-electric Power Take-Off (PTO) for Wave Energy Converters (WECs) is a challenge for device developers. Typically a mechanical PTO solution involves hydraulics, compressed air or gears to convert the high force, low velocity energy flux coming from the WEC into a high velocity, low force form more suited to electrical generation. A conventional rotating electrical machine can then be used, simplifying the Electrical Power Conversion System (EPCS). Further, the mechanical PTO solution permits the storage of energy within springs, compressed air or hydraulic accumulators to reduce the naturally peaky nature of the WEC power flow or tune the resonant frequency of the WEC. The E-Drive project aims to develop an integrated, low-speed, direct-drive PTO for a WEC. The E-Drive PTO would convert mechanical energy from the prime mover directly into electrical energy suitable for the connection to the utility network. The EPCS now needs to be optimised to not only suit the time varying nature of the WEC power output but also to enable control of the WEC. For example, to provide WEC reactive power control. The proposed EPCS solution is modular to improve reliability. It incorporates a Current Source Converter (CSC) as the generator interface, localised energy storage and a multilevel inverter as a grid interface. This paper assesses the viability of the CSC as a generator interface and explores the provision of reactive power control for a case study WEC. Results from the WEC model with the generator and CSC are presented.