The role of converters and their control in the recovery of wave energy

Although mass generation of power from wave energy is still in its infancy, the OSPREY project has made a significant contribution to the development of the necessary technologies necessary to make the process viable. The power electronic interface plays a vital role in the system. It not only gives the opportunity to control the generator torque profile to ensure that optimum energy recovery is achieved for but also affords the luxury of being able to act and react to changes in environmental conditions. Cegelec proposed a common DC bus fed inverter solution. This configuration employs IGBT bridges for control of the generators. Energy recovered is then fed into a common DC link and returned to the supply system via a single fully rated anti-parallel thyristor supply bridge. An anti-parallel supply converter is used so that at times of exceptionally low wave energy, low speed rotation of the turbine can be achieved by reversing power flow (i.e. motoring). This ensures the OSPREY will start and be ready to absorb wave energy