A method and apparatus for operating a renewable energy extraction device

摘要

An energy extraction device and method for extracting energy from a fluctuating energy flow froth a renewable energy source such as wind or wave. The device comprises a hydraulic pump 129 driven by a shaft 125 connected to wind turbine blades 109. The pump 129 is hydraulically connected via a high pressure manifold 133 to a hydraulic motor 131. The pump 129 and motor 131 comprise working chambers displacing a volume of fluid selectable on each cycle by electronic valves (214, fig 2). Pressure in the manifold 133 is measured and a net rate of displacement of fluid by the pump 129 is selected to regulate a torque applied to the shaft 125. The net rate of displacement of working fluid by the motor 131 is selected to smooth energy flow to a generator 157. The net rate of displacement of fluid by the hydraulic motor 131 is selected to cause the pressure within the manifold 133 to tend towards an optimum which is variable.