Reduction of wind turbine power fluctuation by using priority flow divider valve in a hydraulic power transmission

Abstract

This work proposes a novel approach to obtain a nearly constant power output from an offshore wind turbine by incorporating a priority flow divider valve and an accumulator into the power hydraulic system. The priority flow divider valve allows flow in two different ways, i.e. priority line and by-pass line, simultaneously. It controls the fluid (seawater) flow by adjusting its priority port flow as per the user setting to ensure minimum fluctuation of power output, whereas the excess flow is passed through the by-pass port and stored in an accumulator. A control strategy is applied on the control valve to allow the flow from the accumulator to the nozzle as per demand. A mathematical model of wind turbine with hydraulic power transmission is developed by using bond graph technique, which is suitable for this multi-energy domain system. Simulation results show that the output from the wind turbine is stabilized by using the proposed hydraulic power transmission system under fluctuating wind speed.