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.

Chapter Contents:

• 2.1 Introduction
• 2.2 Overview of generator drive train options
• 2.2.1 Fixed speed solutions
• 2.2.2 Variable speed solutions
• 2.3 Overview of generator functionality in ocean energy converters
• 2.3.1 Power conversion
• 2.3.2 Prime mover efficiency optimization
• 2.3.3 Power smoothing
• 2.3.4 Device damping control
• 2.4 Generators in wave energy systems
• 2.4.1 Brush operation
• 2.4.2 Operation and maintenance
• 2.4.3 Corrosive environment
• 2.4.4 Mechanical issues
• 2.4.5 Requirements by WEC category
• 2.5 Generators in tidal energy systems
• 2.5.1 Tidal stream and tidal energy converter characteristics
• 2.5.2 Generator system specifications
• 2.6 Power electronics for generator control in ocean energy converters
• 2.6.1 Control of back-to-back converters in full-converter variable speed configurations
• 2.6.2 Generator-side power converter control
• 2.6.3 Grid-side power converter control
• 2.6.4 Fault operation of variable speed drives
• 2.7 Summary
• 2.8 References

Inspec keywords: power convertors; tidal power stations; asynchronous generators; permanent magnet generators; wave power plants; maintenance engineering; synchronous generators

Other keywords: PTO; wave energy systems; tidal energy system; ocean energy applications; PMSG; marine engineering; ocean energy converters; power take-off efficiency; squirrel cage induction generators; permanent magnet synchronous generators; maintenance engineering; wave energy converter; controller algorithms; electrical generators; power converter technology

Subjects: Power convertors and power supplies to apparatus; Tidal power stations and plants; Asynchronous machines; Plant engineering, maintenance and safety; Wave power; Synchronous machines