In October 28, 2021, the master student Lucas Manosso presented his master thesis by video call. The thesis title is “Design and analysis of a digital hydrostatic transmission for wind turbines”. The main goal of the thesis was to propose a hydrostatic transmission for wind turbines using digital fluid power principles, in order to increase the efficiency of the conventional hydrostatic transmission already developed at LASHIP. The study involved the design, modelling and simulation of a digital hydrostatic transmission. It was developed an algorithm in Matlab, which sizes and selects the most efficient digital hydrostatic transmission configuration. A computational model was developed according to the designed concept in Amesim software. Some simulations were performed comparing both concepts, conventional and digital hydrostatic transmissions, in order to identify the pros and cons of each one. A steady-state analysis showed that the digital hydrostatic transmission is 3% in average more efficient and at partial load operation the difference reaches up to 10%. Dynamic simulations were performed considering a realistic wind profile, concluding that the digital hydrostatic transmission is able to control the ideal rotor speed. However, the digital pump behaviour causes pressure peaks, producing generator frequency oscillations. Nevertheless, the frequency deviations stay under the grid regulations. Yet, in order to prove the system designed, an experimental validation was proposed as future study.
