Electrical generators in ocean energy converters

This chapter provides an outline of the issues confronting the designer of an ocean energy converter (OEC) when selecting or designing the electrical generator and its associated control system. It is clear that, especially for wave energy converters (WECs), this is a complex problem due to the high variance in device power take-off (PTO) type, and indeed the functionality of the generator itself within the power chain. Specification and design of the generator system in tidal energy converters (TECs) have been reviewed and shown to be highly dependent on the device, turbine and current characteristics. Both squirrel cage induction generators (SCIGs) and permanent magnet synchronous generators (PMSGs) are promising generator technologies for application in TECs, showing individual advantages and disadvantages. As important as the choice of the generator technology are the concepts to deal with the special requirements of TEC devices like marine environment, submerged operation and extended maintenance intervals. A consistent requirement in both WEC and TEC system generators is the need for variable speed control and operation. In this context, the power converter technology and controller algorithms related to this need have been introduced.