The present invention relates to braking and positioning methods for a rotor of a wind turbine, more specifically for positioning a rotor at a desired position, e.g. before engaging a locking mechanism. It further relates to wind turbines adapted to carry out the described methods.
Wind turbines are commonly used to convert kinetic energy of an air stream into electric energy. An essential part of a wind turbine is the rotor with rotor blades, which captures the kinetic energy and converts it into rotational energy. For maintenance purposes, it is necessary to fixate the rotor with respect to the wind turbine nacelle in order to avoid any turning movement, which may pose a threat to the maintenance personnel. Conventionally, this requires a cumbersome process involving two persons. One person is located near the low speed shaft, often under highly uncomfortable or even dangerous conditions, and communicates the angular position of the shaft respectively the rotor to a second person controlling the break at the high speed shaft. Once the rotor is positioned in a suitable angular position, a locking mechanism is applied. This kind of rotor lock may be, for example, implemented as a movable bolt and a respective bore or groove in the shaft. At standstill of the rotor, and when the bolt and the bore are aligned, the bolt is manually or automatically moved to engage with the bore. The bolt can only be engaged with the bore in a particular angular position of the rotor.
There is therefore a need for a method and system for the positioning of a rotor of a wind turbine at a predetermined angular position.