Two sensors per blade makes turbine safer

(Above) The lower proximity sensor monitors the hub position.

The pitch control system is among the most important on a wind turbine, say engineers at German turbine manufacturer Vensys Energy AG. The control measures, monitors, and adjusts the working angle of the rotor blades on a wind turbine, which can change its power output. The control also turns the rotor into the wind on start-up, and when operating, it adjusts the blade’s working angle to hold the power output near constant despite changing wind conditions. And during storms, the pitch control positions the blades out of the wind to prevent damage.

“A malfunction can have fatal consequences,” says Vensys’ Director of Electro-Technology Stephan Joeckel. To prevent mishaps, Vensys equips its controls with inductive sensors from Turck Inc, Minneapolis. Each wind turbine has six uprox+ sensors—two on each blade—simultaneously determining the rotor position. Data from all sensors let the controls ensure each blade is in a correct position.

The pitch drive also differs a bit from other turbines. For instance, power transmits between pitch motor and rotor blade through a maintenance-free toothed belt that distributes load across several teeth, thus minimizing wear and increasing safety and reliability.

In one year, Vensys equipped 60 of its wind turbines with Turck sensors. “So far, we have only had good experiences,” says Joeckel. “In addition, the sensor has a high electromagnetic compatibility. The characteristic plays a significant

Vensys Energy turbines in China and elsewhere use several sensors to monitor blade pitch and hub positions.

role in this application because of their nearness to the generator, and the risk of lightening.”

Lastly, wind plant components must meet high sealing requirements because they are frequently located in coastal regions with salt spray and sand. Standard uprox+ sensors are encased in a chrome-plated brass housing with an IP68 protection, which meets Vensys’ requirements. WPE