Long fibre optic sensor system in a wind turbine component

A wind turbine having a fibre optic sensor system for measuring an operating parameter of a wind turbine component, the fibre optic sensor system comprising:

• a light source for outputting light in a predetermined range of wavelengths;
• an optical fibre comprising a long Fibre Bragg Grating, the long Fibre Bragg Grating having a grating of a predetermined grating period extending continuously over a length of the optical fibre to provide a continuous measurement region in the optical fibre,
• wherein the optical fibre is coupled to the wind turbine component such that the continuous measurement region is located at a region of the wind turbine component to be sensed, and such that the grating period at each location in the continuous measurement region is dependent upon the value of the operating parameter at that location;
• a light detector for receiving light from the optical fibre, and for providing an output signal to the controller indicating the intensity and wavelength of the received light;
• a controller coupled to the light detector for determining, based on the detected light, a value for the operating parameter.