A wind turbine blade comprising a system for monitoring the deflection of a wind turbine blade is described. The system comprises a wireless range-measurement system, having at least one wireless communication device located towards the root end of the blade and at least one wireless communication device located towards the tip end of the blade and internally within the blade body. Radio absorbing material is arranged internally in the blade body in the wireless communication path between the root-and tip devices.

A control method, apparatus and system for anti-vortex induced vibration of a wind turbine are provided. With the method, it is determined whether the wind turbine enters an anti-vortex induced vibration mode; an anti-vortex induced vibration function and triggering a window period is enabled in response to the wind turbine entering the anti-vortex induced vibration mode; and a blade of the wind turbine is adjusted to a preset anti-vortex induced vibration position in the window period, where the window period indicates a minimum time to complete the anti-vortex induced vibration function.

Systems, methods, and kits for reducing structural vibrations on wind turbine blades are provided. The actual dynamic structural conditions of a wind turbine blade can be used as a feedback mechanism. A flow control device and a sensor can be installed on a wind turbine blade, and a closed loop control system in operable communication with the flow control device and the sensor can be used to provide closed loop control.

A control method, apparatus and system for anti-vortex induced vibration of a wind turbine are provided. With the method, it is determined whether the wind turbine enters an anti-vortex induced vibration mode; an anti-vortex induced vibration function and triggering a window period is enabled in response to the wind turbine entering the anti-vortex induced vibration mode; and a blade of the wind turbine is adjusted to a preset anti-vortex induced vibration position in the window period, where the window period indicates a minimum time to complete the anti-vortex induced vibration function.