Wind Turbine Blade Root Bending Moment Estimation
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Solution Overview
Problem
Current wind turbine blade monitoring systems face challenges in accurately measuring bending moments, especially at the root end, due to non-linear moment contributions from pitch bearings, which affects the precision and efficiency of load monitoring and can lead to reduced turbine performance and lifespan.
Innovation Solution
A method and apparatus for estimating bending moments in wind turbine blades using sensor sets positioned in the transition or airfoil regions, with signals from these sensors compared to approximation functions to calculate moments at the root end, allowing for accurate estimation without direct measurement at the root, and a sensor system with optical fibers and patch fibers for adaptable configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensors are positioned at the root end of the blade for direct measurement, then measurement precision of root bending moment is improved, but non-linear effects from pitch bearings increase measurement errors and reduce reliability
Solution Approach 1:
The patent uses sensors positioned in the transition or airfoil regions as intermediary measurement points, rather than placing them directly at the root end. These intermediary sensors measure bending moments at locations free from pitch bearing non-linearities, and the root bending moment is then derived through approximation functions that act as mathematical mediators between the sensor measurements and the root moment calculation.
Solution Approach 2:
The patent replaces direct mechanical measurement at the root end with a combination of remote sensing and mathematical approximation. Instead of mechanically measuring the root bending moment directly (which is affected by pitch bearing non-linearities), the system uses sensors at remote locations combined with approximation functions to calculate the root moment, substituting the direct mechanical measurement approach with a sensor-plus-computation approach.
2Reliability
If sensors are positioned in the transition or airfoil regions away from the root, then non-linear effects from pitch bearings are reduced, but direct measurement of root bending moment is lost requiring approximation
Solution Approach 1:
The patent creates a mathematical model (approximation function) that copies or replicates the relationship between bending moment and blade position based on measurements from reliable sensor locations. This mathematical copy allows the system to infer root bending moment information without directly measuring it, preserving measurement reliability while maintaining precision through the calibrated approximation model.
Solution Approach 2:
The patent substitutes direct mechanical measurement at the root with a combination of remote sensing and mathematical approximation. Sensors are placed in the transition or airfoil regions where measurements are reliable, and mathematical approximation functions substitute for the missing direct root measurement, converting spatially separated measurements into accurate root moment estimates.
3Measurement precision
If multiple sensor sets are installed at different positions along the blade, then measurement coverage and accuracy are improved, but device complexity and manufacturing costs increase
Solution Approach 1:
The patent applies local quality by positioning sensor sets specifically in the transition or airfoil regions where measurements are most reliable, rather than uniformly distributing sensors along the entire blade. This localized sensor placement optimizes measurement quality in the critical regions while minimizing overall system complexity.
Solution Approach 2:
The patent makes the sensor sets multi-functional by using them not only for direct local measurement but also as input data for calculating bending moments at multiple positions along the blade through approximation functions. Each sensor set serves multiple purposes: local monitoring, root moment calculation, and intermediate position estimation, reducing the need for additional sensors.
Data Source
AI summary
Method and blade monitoring system for monitoring bending moment of a wind turbine blade. The method comprises obtaining a first sensor set signal indicative of a first bending moment at a first sensor position different from the tip end along the longitudinal axis of the wind turbine blade, and estimating a bending moment at a first estimation position along the longitudinal axis based on the first sensor set signal, wherein the first sensor position is different from the first estimation position along the longitudinal axis. The blade monitoring system comprises a processing unit and an interface connected to the processing unit, the processing unit being configured for performing the method.