Performance Requirements of Hydraulic Pumps/Motors Related to Non-Conventional Energy Sources

Abstract

Hydraulic pumps/motors can be connected to different systems which utilize non-conventional energy. These systems produce unsteady output energy even when a control policy is adopted to stabilize it. Therefore, in such systems, hydraulic pumps/motors work under dynamic conditions. This paper presents examples of wind energy conversion systems with different control policies. The available daily wind-power distributions at El-Minia, Wadi El-Natrun and Hurghada in Egypt are calculated. A suitable cut-in wind power is chosen for each site. The maximum rate of change of the available power is determined. The starting input power required to drive a hydraulic gear pump and a hydraulic gear motor, experimentally measured, is compared with the cut-in wind power at the studied sites. An example of the speed dynamic response of the pump and motor is illustrated. The study in this paper reveals that specifications of hydraulic pumps/motors should include, in addition to the static performance, both their frictional torque and dynamic behaviour as well.