Research on reducing flow shock of the digital hydraulic wind turbine

Abstract

The wind turbine with digital hydraulic transmission can make the corresponding hydraulic pump work according to the wind speed, so that the hydraulic wind turbine can maintain high efficiency at the whole working wind speed. However, the switching of different displacement hydraulic pumps will cause a large flow impact on the hydraulic system of the wind turbine, affecting its working characteristics and the absorption of wind energy. Based on the analysis of the working principle of the digital hydraulic wind turbine, the scheme of a 5 MW wind turbine is designed and the AMESim model is established. The dynamic characteristics of the digital hydraulic wind turbine under two switching modes are compared. An advance valve closing control strategy is proposed to reduce the instantaneous flow impact. Simulation results show that the control strategy diminished the system flow shock by about 50% when switching the hydraulic pump. Finally, a hardware-in-loop system with a 5.5 kW digital hydraulic turbine is built to verify the effectiveness of the proposed control strategy. The research results provide a theoretical basis and technical reference for the efficient utilization of wind energy and stable operation of the digital hydraulic wind turbines.