Ice accumulation on wind turbines has a relevant influence on operational management during the cold season. In addition to reduced yield due to altered aerodynamic properties, the safety of the turbine and its surroundings is a central issue.
For early and accurate detection of icing, we offer – also retrofittable – on-blade sensor systems based on wireless, flexible and energy-autonomous smart sensors measuring directly on the surface of the rotor blades.
Wireless and flexible smart sensors are powered by solar energy almost indefinitely. Each sensor measures the temperature with an accuracy of 0.25°C and indicates the icing condition in several discrete levels. The unique, patented design (flexible, less than 2 mm thick) allows the sensors to be mounted on almost any part of the rotor blade, as well as on other structures such as the nacelle or tower. The mounting is done by using a self-adhesive erosion protection foil.
The base station (one unit per installation) receives the data packages sent out by the sensors via radio. It is typically installed as a component in the nacelle, but can also be mounted in the spinner, in the tower base or on the ground. Several variants of communication interfaces (e.g. ModbusTCP, relay changeover contacts, GSM/3G, Ethernet, etc.) are available to integrate the data into plant control, SCADA systems or condition monitoring systems.
On request, we also offer access to our online dashboard. Here, live data as well as historical data can be viewed and exported.
Tested and awarded by leading certification bodies and foundations, including TÜV Nord, DNV and Solar Impulse Foundation. In use by several major wind turbine manufacturers and companies worldwide.
Nacelle
Outside on the blade surface
inside the rotor blade
no
yes
no
no
yes
no
0m/s
0m/s
2-3m/s
no
no
yes
not necessary
not necessary
not necessary
no
yes
yes, starting at 2-3m/s
Screwed nacelle
Self-adhesive on the blade
Glued inside the blade
n. a.
yes – continously
no (partial imbalance indicator)
The flow conditions at the nacelle are different from those at the rotor blade. On the one hand, these are naturally due to the rotation of the rotor blades, on the other hand to the different heights above ground. Especially due to the trend towards even larger rotor diameters and increasing tower heights, an even greater effect can be foreseen here in the future.
Due to this situation, the sensors must be designed to be correspondingly sensitive and conservative in order to be able to reliably detect ice accumulation. However, this can lead to the turbine being shut down earlier than actually needed. Furthermore, the measurement on the nacelle cannot determine at what point the icing on the rotor blades is gone again. Therefore, no automatic restart is possible with such systems.
Completely different technologies – vibration-based systems measure indirectly inside the blade and thus conclude on ice, and always need a minimal excitation of the rotor blades by the wind. These systems use the change in the eigenfrequency of the blades to draw conclusions about possible ice accumulation. Therefore, no ice can be measured when the turbine is idling or at a standstill, which means that no ice can be detected during this period – furthermore, the systems need data from the wind turbine in order to work.
Best-in-class: Independent study from VGB
In the course of the VGB project, a comprehensive field test was carried out in which four rotor blade-based ice detection systems were installed and tested on the same wind turbine.
The field test was carried out at the Stor-Rotliden wind farm in Västerbotten, Sweden on a Vestas V-90.
Results for the on-blade ice detection system:
