Dynamic modelling of a large-scale horizontal-axis wind turbine coupled to a hydraulic pump

Abstract

The recent increase in demand for wind turbines has given rise to concerns about the availability of materials used in their construction. The combination of a wind turbine coupled to a hydraulic pump, instead of an electrical generator, offers an alternative application for this renewable energy technology. This article analyses the dynamic response of a wind/hydraulic system consisting of a wind turbine driving a swash-plate pump. This is done by means of mathematical models utilising MATLAB® and Simulink®. The operational aspects of the proposed wind/hydraulic pumping system are validated against the standard baseline 5-MW wind turbine model of the National Renewable Energy Laboratory. Control issues encountered in wind turbines and hydraulic systems are analysed, with the wind turbine control systems used to run electrical generators being adopted to control the pressure-controlled swash-plate pump. The pump lends itself to such applications as it can be controlled by varying the swash-plate angle, thus controlling the pump’s output power and torque. Methods for the generation of artificial wind data are also included, and a simple wind speed time series is developed. This time series is used to test the wind turbine hydraulic system under varying wind conditions using the concept of ‘control regions’. The models developed show the standard steady-state response of the wind turbine together with the dynamic behaviour of the wind turbine. Once the control parameters are established, the system also presents a wind turbine controller and analyses the behaviour of the system under typical and extreme wind conditions. This study concludes that such a system has significant potential to be technically achievable.