Abstract
This paper presents the design, modelling, and simulation of a digital hydrostatic transmission (D-HST) for wind turbines using fixed and variable displacement hydrostatic machines. A sizing algorithm is developed considering real efficiency data in order to optimize the selection of components and set the most energy efficient configuration. The design of a D-HST for a 28.5 kW wind turbine is carried out. Considering the use of a synchronous generator, the best D-HST configuration is set with two fixed pumps and a variable motor. A computational model is developed according to the designed system. The D-HST is compared to a conventional hydrostatic transmission (C-HST), made up by a fixed pump and a variable motor. The model of the C-HST used as a baseline was validated using an experimental setup and that is modified according to the new designed system. Steady-state and dynamic analysis are done, in order to identify the pros and cons of each concept. Furthermore, a comparison with other wind turbine drivetrains is carried out including: a widespread solution drivetrain made up by a gearbox and a doubly-fed induction generator with frequency converter; a digital displacement hydrostatic transmission; and a direct-drive wind turbine.
