Blade load monitoring on wind turbines

Measurement and monitoring of blade loads, or blade load monitoring with „Turbine Load Control“, is the prerequisite for many further applications:

  • If blade loads are captured in real time, rotor loads can be actively reduced when the turbine is equipped with Individual Pitch Algorithms.
  • If blade loads are measured and monitored over many years, an estimate of the remaining lifetime can be made by using the load spectrum.

Knowledge of blade loads essential for further optimizationBlade load monitoring with Turbine Load Control

Together with our customers we are developing applications for extreme load minimization, lift optimization, remote monitoring, yaw optimization, damage early detection, Ice detection and imbalance minimization based on our measurement technology. The analysis that we have carried out together with our customers and other experts in wind power show that it is possible to reduce costs of electricity generation (CoE, levelized cost of Electricity) by 5-6%. In a 3MW onshore turbine, this corresponds to an annual saving of more than 20 thousand euros.

Together with our customers (manufacturers and suppliers from the wind energy industry) we use our measurement system, based on the fos4Test series measurement devices, for R&D applications. Here our temperature-compensated fiber optic strain sensors and our fiber optic vibration sensors are used. Additionally, we actively support our customers in the series integration of our measurement systems in wind turbines.

Background

With increasing rotor diameters, the wind loads become more inhomogeneous on the rotor blades of wind turbines. This leads to additional mechanical excitation of the entire drive train. Such additional vibrations means increased vibration loads on the entire system and are associated with a reduced power efficiency and decreased availability of the wind turbine. A load-dependent individual control of the blade angle (Individual Pitch Control) can help.

For this purpose, the measurement of the blade root bending moments is necessary. Additionally, the detection of the dynamic blade loads is required for the condition monitoring of rotor blades, which means structural health monitoring, ice detection or derivation of the load spectra. Due to harsh environment and the required lifetime, conventional measurement technology is in most cases not suitable. Fiber optic sensors fulfill the reliability and lifetime requirements.