HYDRIVE - Hydrostatic Drive Train Transmission for Renewable Energy Applications

The electric production capacity for wind turbines have been steadily increasing, and turbines producing 5-6 MW electric power are in service today. Typically, the power transmission system consists of a mechanical gear box connected to an electric generator, which in turn is connected to the electric grid through a frequency converter. At these elevated power levels, the used technology is pushed to the edge by the increasing demands for efficiency, power density, reliability, serviceability besides requirements for size, weight and cost reductions. On this background, and based on recent advances in fluid power technology, the major objective of the research project is to investigate the digital displacement technology – and its use for high-power hydrostatic transmission in both wind turbines and in wave energy converters.

In wind turbine applications benefits would be: no mechanical gearbox, no frequency converter, no transformer and no need for costly rare earth permanent magnets used in direct-drive PM generators. The anticipated results are higher reliability and higher up-time – being the two single most important factors today. Add to this an increased power density and significant nacelle weight reduction, the latter having a huge cost reduction effect on the structural design and the foundation. In wave energy fluid power technology is the only viable solution for the power take off system due to extremely high forces and slow bidirectional movements.