The role of converters and their control in the recovery of wave and wind 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, but also affords the luxury of being able to act and react to changes in environmental conditions. The author describes the synchronous and induction generator drive converters. The latter is based on the use of voltage source force commutated technology due to the need for four quadrant operation. IGBT (insulated gate bipolar transistor) based inverters offer the most advanced control and highest performance. At present this technology is available up to ratings of approximately 1.5 MW. GTO (gate turn off thyristor). The author also discusses constant speed, power and torque control. The addition of a wind turbine to OSPREY is also considered.