Method and apparatus for extracting energy from a fluctuating energy flow from a renewable energy source

摘要

A hydraulic pump is driven by a rotating shaft, driven in turn by a renewable energy source. A hydraulic motor drives a load and a high pressure manifold communicates between the pump, motor and an elastically deformable fluid retaining body. The pressure in the high pressure manifold is measured and the net rate of displacement of working fluid by the hydraulic pump is selected responsive thereto to regulate the torque applied to the rotating shaft. The net rate of displacement of working fluid by the hydraulic motor is selected to smooth the energy flow to the load. The net rate of displacement of working fluid by the hydraulic motor is selected to regulate the pressure in the high pressure manifold to remain within an acceptable pressure range.

主权项

1. A method of operating an energy extraction device to extract energy from a fluctuating energy flow from a renewable energy source, the device comprising: a hydraulic pump driven by a rotating shaft, the rotating shaft driven by a renewable energy source, a hydraulic motor driving a load, at least one low pressure manifold and a high pressure manifold in fluid communication with an outlet of the hydraulic pump, an inlet of the hydraulic motor and an elastically deformable fluid retaining body, the hydraulic pump and hydraulic motor each comprising a plurality of working chambers of cyclically varying volume and a plurality of valves for regulating a volume of working fluid displaced by each said working chamber between each said working chamber and each said manifold, at least one valve associated with each said working chamber being an electronically controlled valve, said electronically controlled valves being operated to select the volume of working fluid displaced by each said working chamber on each cycle of said working chamber and thereby regulate a net rate of displacement of working fluid by each of the hydraulic pump and the hydraulic motor,
the method comprising: measuring a pressure in the high pressure manifold, selecting the net rate of displacement of working fluid by the hydraulic pump responsive to said measured pressure to regulate a torque applied to said rotating shaft, selecting the net rate of displacement of working fluid by the hydraulic motor to smooth the energy flow to the load, and further selecting the net rate of displacement of working fluid by the hydraulic motor to regulate the pressure in the high pressure manifold to remain within an acceptable pressure range, wherein the acceptable pressure range comprises a first range and one or more second ranges, either higher or lower than the first range, and the pressure within the high pressure manifold is regulated more strongly when the pressure is within the or each second range than in the first range by virtue of the net rate of displacement of working fluid by the hydraulic motor being varied, to change the pressure in the high pressure manifold, responsive to the same magnitude of pressure change in the high pressure manifold, by a larger amount in the or each second range than in the first range.