Control of floating wind turbines

Wind energy is a clean, renewable and extremely fast growing form of electricity generation and the potential to install turbines deep offshore is only just being realised. The vast majority of commercial offshore turbines have foundations on the seabed thereby restricting the depths at which offshore farms can be installed. In an attempt to facilitate access to a potential multi-Terawatt resource, a number of floating concept wind turbines have emerged. In this tutorial paper we review the control challenges associated with the design of floating turbines and summarise recent developments in the area. Of particular interest is a fore-aft oscillation induced by attempting to regulate the generator speed to its rated value. The paper concludes with a discussion of how the control problems presented are likely to change with increasing turbine size and structural flexibility.