Gearbox is a concern in modern wind turbines, increasing the maintenance cost and therefore the cost of energy (COE). A hydrostatic transmission (HST) improves the turbine drivetrain reliability by using slightly compressible mineral oil as the working medium rather than a rigid gearbox. An HST eliminates the power converter since it is a continuous variable transmission (CVT), making the turbine simpler and more cost effective. The turbine operates below the rated wind speed for a considerable time in a year, making the variable hydraulic motor run at partial displacement for the most common configuration of a hydrostatic wind turbine, a fixed displacement pump and a variable displacement motor. This results in low drivetrain efficiency. Moreover, large variable displacement motors for megawatt turbine are commercially unavailable. A digitalized hydrostatic drive for a modern wind turbine is proposed to improve the drivetrain efficiency at low wind speeds. The digital coding method for hydrostatic wind turbine is studied. A dynamic simulation model of the digitalized hydrostatic (dHST) wind turbine has been developed in Simulink. A widely used efficiency model for the hydrostatic pump and motors is used in the simulation to make the study practical. The proposed digitalized hydrostatic solution has been compared with a conventional hydrostatic solution. Simulation results show the benefits of digitalized hydrostatic transmission over conventional hydrostatic transmission in drivetrain efficiency, system complexity and cost.

This content is only available via PDF.
You do not currently have access to this content.