A system and method for protecting an idling wind turbine power system from damage during loss of grid power. The wind turbine power system has a plurality of rotor blades. The method includes monitoring an incoming wind direction at the wind turbine power system. When the incoming wind direction is changing at a predetermined attack angle, the method also includes rotating at least one of the rotor blades of the wind turbine power system to a pitch angle that is offset from a feather position by a predetermined number of degrees to reduce and/or eliminate flutter phenomenon from occurring.

Rotor restraining and rotating apparatus and methods for a wind turbine (1) are described. An apparatus (200) has a rotatable control element (204) associated with a rotor (8, 203) of the wind turbine, the control element being at least part-circular in form, the control element comprising a plurality of engagement formations (205) disposed on a periphery thereof. The apparatus also has a control member (206), comprising a plurality of engagement formations (207). The control member is movable (208) in a first degree of freedom between: (a) a non-restraining position; and (b) a restraining position in which the control member engagement formations are able to engage the control element engagement formations to restrain rotation of the control element. The control member is also movable (209) in a second degree of freedom. In the restraining position, on movement of the control member in the second degree of freedom, the control member engagement formations are operable to move the control element engagement formations thereby to cause rotation of the control element.

A wind turbine system comprising a plurality of wind turbine modules mounted to a support structure, wherein each of the wind turbine modules comprises a rotor including one or more variable-pitch blades, each defining a respective blade pitch angle and being controlled by a pitch control system, and a control system operable to control the blade pitch angles of the plurality of blades of the wind turbine modules. The control system is configured to identify the presence of a predetermined stop condition and, in dependence thereon, is operable to control the blade pitch angles of the respective blades to predetermined stop positions that reduce oscillation of the support structure. Aspects of the invention also relate to a method of controlling a wind turbine system, to a controller for implementing the method, and to a computer program product.

The invention is directed to a wind turbine system comprising a first pair of wind turbines mounted to a support structure by a first support arm arrangement, and a second pair of wind turbines mounted to the support structure by a second support arm arrangement. The first and second support arm arrangements are mounted to the support structure at a respective yaw unit so as to yaw about the major axis of the support structure. Moreover, the wind turbine system further includes a control system that is configured to control the yaw angle of each of the first and second support arm arrangements, wherein the control system is configured to identify the presence of a predetermined shutdown condition and, in response, the control system is operable to control the yaw angles of the first support arm arrangement and the second support arm arrangement to a predetermined safe state.

Methods (200) for reducing vibrations in one or more rotor blades (120) of a wind turbine (160), when the wind turbine is in standstill conditions are provided. The method comprises measuring (201) one or more deformation parameters indicative of deformation of one or more blades (120), determining (202), at a dedicated controller (190) for an auxiliary drive system (20, 107), a vibration of one or more of the blades (120) based on the deformation parameters, wherein the dedicated controller (190) for the auxiliary drive system is separate from the wind turbine controller (180), and generating (203), at the dedicated controller (190), an output signal to operate the auxiliary drive system to reduce the vibration. Also disclosed are wind turbines (160) which comprise a dedicated controller (190) configured to determine a vibration and generating an output signal to reduce the vibration, when the wind turbine is in standstill conditions.

A method and an apparatus for yaw control of a wind turbine under a typhoon. The method for yaw control may include: determining, before or when the typhoon comes, whether there is a fault in a yaw system of the wind turbine; performing a normal yaw control over the wind turbine according to the wind direction, if determination is negative; and performing a yaw control corresponding to the fault on the wind turbine according to the wind direction, if determination is positive. The yaw control corresponding to the fault is performed before or when the typhoon comes, in case of one of a yaw drive mechanism fault, an electronic brake mechanism fault, or a hydraulic brake mechanism fault. The wind turbine is downwind oriented and yaw load reduction is achieved.

A wind turbine includes a main shaft (34), a rotor hub (22), a plurality of blades coupled to the rotor hub (22), and a rotor locking disc (32), (32). The main shaft (34) includes a front end portion (34a), and the front end portion (34a) includes a first connecting structure (36). The rotor hub (22) includes a second connecting structure (40). The first connecting structure (36) of the main shaft (34) is fixed to the second connecting structure (40) of the rotor hub (22). The rotor locking disc (32), (32) is integrally formed on the front end portion (34a) of the main shaft (34), and includes a peripheral region. A plurality of rotor locking elements (50), (50) are located in the peripheral region for receiving one or more rotor locking pins (30).

A method for protecting a wind turbine from extreme and fatigue loads associated with high wind speed events includes receiving, via a wind turbine condition estimator programmed in a turbine controller of the wind turbine, operating data indicative of current wind turbine operation. Further, the method includes determining, via the wind turbine condition estimator, a plurality of estimated wind turbine conditions at the wind turbine by solving a control algorithm having one or more equations using the operating data. The estimated wind turbine conditions include, at least, an estimated wind speed at the wind turbine and a loading proxy of the wind turbine. As such, the method includes implementing, via the turbine controller, a corrective action only when each of the estimated wind turbine conditions indicates that one or more loading conditions of the wind turbine exceeds a predetermined limit.

Provided is a method for operating wind energy converters, in particular of a wind farm. The power limitation mode in this case comprises the steps of turning off at least one of the wind energy converters and operating at least one wind energy converter different to the turned-off wind energy converter, activating a generator heating of the turned-off wind energy converter, turning off the working wind energy converter at or after occurrence of a predefined event, in particular after a predefined time period has elapsed or when a predefined instant is reached, and activating the generator heating of the wind energy converter turned off at or after the occurrence of the predefined event. Provided is a wind farm and to a wind energy converter for carrying out such a method.

A rotor arresting device, to a wind turbine and to a method for arresting and/or rotating a rotor. The rotor arresting device comprises a rotor, a rotational assembly, and a static assembly fixed in position, comprising a toothed disk, which can be arranged on the rotational assembly, having a plurality of arresting recesses arranged along a circumference, wherein two adjacent arresting recesses form a tooth, a first arresting module having at least one first arresting element, a second arresting module having at least one second arresting element, wherein the first and the second arresting module can be arranged on the static assembly, wherein the first and the second arresting element are arranged and designed to engage in arresting recesses of the toothed disk, wherein the spacing of the first arresting element from the second arresting element in the circumferential direction of the toothed disk is a non-integral multiple of a tooth tip spacing of the toothed disk.