Independent laser measurement coincides with data from eologix:align

This case study compares results recorded with the eologix:align-system and an independent measurement system on a FL MD77 wind turbine in Poland. The eologix:align system enables continuous monitoring of pitch angle deviations between the rotor blades. To validate the results, the pitch angle differences of the turbine were compared by means of results from a ground-based measurement at time X.

Wind farm: Poland

Turbine type: Fuhrländer FL MD77

Four causes for the emerge of relative blade angle deviations

Variation in quality
Rotor blades must be reproduced precisely to ensure efficiency and safety. Variations in manufacturing quality can lead to unwanted aerodynamic forces that amplify pitch angle errors.
Service and maintenance operations
If maintenance is neglected, this can lead to loss of performance, safety risks, expensive repairs, rising operating costs and a shortened service life of the wind turbine.
Incorrect or missing blade marks
Efficiency and energy production are reduced and damage occurs. Regular monitoring and maintenance of the blade marks are crucial to avoid these problems.
Incorrect settings
If the pitch angles are set incorrectly, the efficiency of the turbine will be significantly impaired. If they are too flat or too steep to the wind direction, this leads to lower energy production.

How does eologix:align work?

Measurements with the eologix:align system are taken several times a day at regular intervals. They ensure a detailed recording of the rotor rotations in different operating states. Based on the measured acceleration data, both the rotational speed of the rotor and the alignment of its blades to each other are calculated via special algorithms (see figure 1).

Deviations in blade pair A-B of a Fuhrländer wind turbine — Figure 1: In the measurement period, deviations can be seen in blade pair A-B

As shown in the figure above, clear deviations are visible in the blade pairings A-B and B-C. This indicates that blade B is not correctly aligned. To validate the result of the eololgix:align system, an external laser measurement of the blade angle deviations was carried out for this system in calendar week 17. The results of this instantaneous measurement were compared with the average measurement results of eologix:align from the same week.

eologix:align – Pitch angle error detected

For the period under observation, the external measurement also shows slightly increased differences between the blade pairings A-B and B-C. Although these are slightly smaller, they also point to blade B as the main cause of the relative blade angle differences.

Results of pitch angle measurement — Figure 2: Comparison of the relative blade angle deviations of the eologix:align results with the external laser measurement results

This case study demonstrates that the eologix:align system was successfully able to measure the relative pitch angle differences on a Fuhrländer FL MD77 turbine. Significant deviations of the pitch angles could be detected. This example clearly shows the benefit of monitoring pitch angle differences. This should be done continuously, as various factors such as maintenance work or possible system errors can lead to deviations at any time. Overall, this example emphasises the high effectiveness and accuracy of eologix:align in measuring relative pitch angles on wind turbines.