Magnetostrictive sensors’ benefits for wind turbines

Magnetostrictive linear position sensors are designed for advanced motion control implementations and can be integrated into a wide range of applications. They have a modular construction and immunity against electromagnetic interference (EMI). The interface allows the simultaneous detection of four magnets using only one sensor with a stroke length up to 20 m, which is a great advantage particularly in the print and paper industries as well as renewable energy, testing machines, metal working processing, and wind turbines. For harsh environments, the sensor can add IP69K protective housing. The interface, signal transmission, and exact position measurement of magnetostrictive linear position sensors make them suitable alternatives to reed-chain based sensors or limit switches. 

CANopen, magnetostrictive sensors in the wind industry

Magnetostrictive sensors are used for position feedback in the closed loop control for the pitch of rotor blades: they measure position with high accuracy even under tremendous aerodynamic forces and continuously changing wind conditions in which wind turbines operate. To ensure the highest safety during maintenance, locking cylinders keep the rotor blades of wind turbine stationary and positioned precisely. The extending and retracting movement of the locking bolt makes the wind turbine lock and unlock. The detection of the locking/unlocking position also can be monitored with sensors. They provide operation and functionality in difficult maintenance situations due to rotor height or in challenging climatic conditions of offshore turbines.

Whenever the wind’s velocity and direction changes, the pitch control adjusts the angle of the rotor blades by a few degrees to maximize the output for all wind speeds. When the wind velocity exceeds the maximum permissible generator output, the blades are adjusted away from the optimum position to reduce the aerodynamic efficiency and maintain constant rotation. Conversely, the blades are turned back into the wind whenever the wind speed drops again. Actively controlling the rotation speed enables peak efficiency, reduces the stress on the rotor and tower, and is the foundation for increased safety and longevity.

Moira Lise, MTS Sensors. This article originally appeared on the CAN in Automation (CiA) website. CAN in Automation is a CFE Media content partner. Edited by Chris Vavra, production editor, Control Engineering, CFE Media, cvavra@cfemedia.com.

www.controleng.com keywords: linear sensors, wind turbines 

• Magnetostrictive linear sensors are designed for harsh conditions and extreme settings.
• The CANopen interface allows four magnets to be detected simultaneously, which improves accuracy.
• Magnetostrictive linear sensors with CANopen are used for position feedback in closed-loop control for wind turbines to improve performance.

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