Dynamic Analysis of a Floating Wind Turbine with a Hydraulic Transmission System

Abstract

A 5 MW spar-type floating wind turbine equipped with high-pressure hydraulic transmission machinery is presented in this paper. The hydraulic transmission system consists of a hydraulic pump, a nonreturn check valve, a high-pressure accumulator and a hydraulic motor. A dynamic model of the hydraulic system is developed in a state space form. The hydraulic model is coupled with the aero-hydro-elastic code HAWC2 through an external Dynamic Link Library (DLL) using the Runge-Kutta-Fehlberg method with step size and error control. The dynamic responses of the studied floating wind turbine are investigated under turbulent wind and irregular wave conditions. Simulation results show that for the considered load case, the accumulator can store energy and absorb parts of the pulsating flow of hydraulic fluid and thus the wind turbine system with accumulator has better dynamic response characteristics.