Rotor Imbalance – the underestimated danger for your wind turbine generators
Bending
Torsion
Tilting
How does rotor imbalance evolve?
There are two reasons for rotor imbalance:
- Aerodynamic imbalance, caused by deviations in blade angles and blade twists as well as blade damages
- Mass imbalance, caused by different weight distributions within the rotor
Consequences of rotor imbalance
Rotor imbalance causes vibrations in axial and lateral directions, which result in enhanced tower and nacelle movements (graphics above).
Long-term consequences of rotor imbalance:
- Lifetime reduction of major components
- Energy yield reduction caused by decreased efficiency
- Down times due to repair or replacement of damaged components
Frequency of rotor imbalance
Findings of a case study on 240 wind turbine generators
%
Unacceptable:
45% of wind turbines show inadmissible
rotor imbalance
%
Tolerable:
30% of wind turbines show a level below the limit, but increasing vibrations
and small energy yield loss
%
Low rotor imbalance:
25% of wind turbines show a well balanced rotor with minimized vibrations
Rotor imbalance can be corrected by TerraScan
Overview of the TerraScan principle:
1. Data collection and analysis
Turbine type, blade type, error log, site conditions
2. Turbine inspection and blade angle analysis
Turbine inspection and blade angle analysis, Turbine inspection, condition evaluation, optical blade angle analysis (accuracy: 0,1°)
3. Evaluation and recommendation of action plan
Evaluation and recommendation, Inspection report including recommendations for blade angle corrections
and vibration analysis
4. Imbalance correction
Supervision of blade angle corrections, performance of vibration analysis with subcontractors
Overview TerraScan-benefits for your wind farm
