Development of a novel holistic model-based design for hydraulic accumulator in hydraulic wind turbines

Hydraulic wind turbines (HWT) are promising solutions to replace traditional mechanical transmission. In HWT, Hydraulic accumulators are used to absorb the flow rate fluctuations on the high-pressure pipeline connecting the hydraulic pump (HP) and the hydraulic motor (HM) to guarantee stable working operations. Despite this importance, a lack in the modelling and correspondent validation is observed on the design procedure of the accumulator and its integration with HP and HM. Hence, to fill this knowledge gap, a novel holistic design tool has been developed for a new accumulator design considering its integration with the circuit. Thank to this, the paper outlines a proper HP and HM choice minimizes the accumulator volume. The model can also assess the maximum storable energy by the accumulator addressing the scientific attention to the energy density which is the main limiting aspect of the device. To support the validity of the model and add a novel contribution to the matter, it has been experimentally validated through data available in literature demonstrating the consistency of the model. Once validated, the model was acted as a software platform to assess the impact on the hydraulic transmission chain of the main parameters defining the accumulator design. As design result of the study performed, a 50 % reduction of the pressure fluctuations with respect to the conventional design of the accumulator has been obtained. Moreover, the maximum storable energy increases up to 65 %. This allows to handle situations of unexpected greater wind speed variations or an easier emergency management.