Design, analysis and control of hydraulic soft yaw system for 5MW wind turbine

As wind turbines increase in size and the demands for lifetime also increases, new methods of load reduction needs to be examined. One method is to make the yaw system of the turbine soft/flexible and wereby dampen the loads to the system. This paper presents work done on dampening of these loads by active control of a hydraulic yaw system. The control is based on a non-linear and linear model derived based on a concept yaw system for the NREL 5MW wind turbine.
The control strategies show a reduction in pressure pulsations under load and it is concluded that the strategie including high-pass pressure feedback is the most suitable for this application.