Moog Japan Ltd began to offer a system that detects the stress on each of the blades of a windmill for power generation and adjusts the blade to an optimal pitch angle.
Four load sensors are installed at the base of each blade to measure distortion. The system adjusts the pitch angle to reduce the load on the wings when the wind is strong or when asymmetric load is applied on the windmill due to variations in wind strength. The adjustment will extend the lifetime of a windmill and reduce power generation cost.
The system uses sensors that incorporate a fiber bragg grating inside an optical fiber and detects changes in the grating space caused by distortion from changes in the light. It can measure distortions up to 4,500 μstrain (0.45%) at a resolution of 1 μstrain and 25 times per second.
This technology was acquired from Insensys Ltd of Britain, which Moog Inc of the US, the parent company of Moog Japan, took over Jan 30, 2009. The system actually reduced the load applied on blades by 10 to 20% and the load on the whole tower by up to 20%, according to Moog Japan.
Also, the measuring system is applicable to the "Rotor Monitoring System," which is used to detect icing on blades and lightning damage.
Large windmills in the 5MW class have blades as long as 60m, and the highest point of the blades can be 125m above the ground. Therefore, the windmills are frequently subjected to instantaneous and asymmetric wind forces, which cause early wear of components, leading to early breakdown and a short lifespan.