The role, type and composition of the yaw system
The yaw system is a unique servo system for wind turbines. The main role of the yaw system is two. The first is to cooperate with the control system of the wind turbine to make the wind turbine of the wind turbine always in the windward state, make full use of the wind energy, improve the power generation efficiency of the wind turbine, and provide the necessary locking torque when the wind direction is relatively fixed, so as to ensure Safe operation of wind turbines. The second reason is that the wind turbine may continue to yaw in one direction, in order to ensure that the cable of the overhang portion of the unit does not cause excessive twisting, the cable is broken and failed, and the winding can be automatically released when the cable reaches the designed winding value.
There are various options for yaw systems, such as damped yaw systems, fixed yaw systems with yaw brakes, soft yaw systems, damped free yaw systems, and controlled free yaw systems. There are two types of applications that are most commonly used today, one is a damped yaw system with a sliding bearing, and the other is a fixed yaw system with a yaw brake.
The yaw system consists of two parts: the yaw control mechanism and the yaw drive mechanism. The yaw control mechanism includes a wind direction sensor, a yaw controller, a cable unwinding sensor and the like, and the yaw drive mechanism comprises a yaw bearing, a yaw drive device, a yaw brake (or a yaw damping device) and the like.
Damped yaw system with sliding bearings
The yaw system of the plain bearing is a damped yaw system. The bearing is between the tower and the nacelle, which transmits various forces from the nacelle to the tower through the bearing pads. The bearing pads of plain bearings are mostly made of engineering plastics. This material (such as PETP, which is better than nylon) has good comprehensive properties including mechanical properties, heat resistance, wear resistance, chemical resistance and self-lubrication. Sex, and low friction coefficient, have certain flame retardancy, easy processing, and good corrosion resistance. Due to the unique mechanical properties of this material, this type of bearing can work even in the absence of lubrication. The bearing bush is composed of an axial upper thrust tile, a radial thrust tile and an axial lower thrust pad. They are used to withstand the axial force generated by the weight of the nacelle and the wind turbine parallel to the direction of the tower, and the radial force transmitted by the wind turbine to the nacelle perpendicular to the tower and the overturning moment of the nacelle. Thereby, various forces and moments received by the nacelle are transmitted to the tower through the three bearing pads.
