Wind Turbine Rotor Blade Load Calibration Under Aerodynamic Forces
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Solution Overview
Problem
Existing methods for calibrating load sensors on wind turbine rotor blades are inaccurate in strong winds due to neglecting aerodynamic influences, leading to potential damage and reduced service life.
Innovation Solution
A method for calibrating load sensors on rotor blades that accounts for aerodynamic forces by determining a correction component based on wind conditions, rotor blade angle, and axial inclination, allowing calibration during operation, especially in strong winds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If calibration is performed during wind turbine operation in strong winds, then calibration frequency and timeliness are improved, but measurement accuracy deteriorates due to aerodynamic influences
Solution Approach 1:
The patent applies parameter changes by introducing a correction factor that accounts for aerodynamic influences varying with wind speed. The calibration process transitions from assuming static gravitational load only to incorporating dynamic aerodynamic forces as wind conditions change, allowing accurate calibration during operation across different wind speeds
Solution Approach 2:
The patent implements feedback by using measured wind speed as input to calculate aerodynamic forces, which then generate correction factors that adjust the calibration. This closed-loop approach continuously refines the calibration accuracy based on real-time wind conditions, enabling frequent recalibration without sacrificing precision
2Device complexity
If aerodynamic influences are neglected during calibration, then calibration process simplicity is improved, but calibration accuracy deteriorates in strong winds
Solution Approach 1:
The patent modifies the calibration model by adding aerodynamic force parameters that become significant at higher wind speeds. The correction factor incorporates wind speed-dependent aerodynamic influences, transforming the calibration from a simple gravitational load model to a comprehensive model that accounts for both gravitational and aerodynamic forces
Solution Approach 2:
The patent applies partial action by introducing aerodynamic correction factors only when wind speeds exceed predefined thresholds. At low wind speeds where aerodynamic forces are negligible, the simple gravitational calibration suffices. At high wind speeds, the additional aerodynamic terms are activated to maintain accuracy without unnecessarily complicating low-wind calibration
3Ease of operation
If calibration is performed only when turbine is stationary, then calibration simplicity is improved, but calibration flexibility and repeatability deteriorate
Solution Approach 1:
The patent transitions the calibration system from static to dynamic by enabling calibration during turbine operation. The measuring device and control system work together to perform calibration at various operating points, allowing the calibration to adapt to different wind speeds and rotational states, thereby improving flexibility and repeatability
Solution Approach 2:
The patent makes the calibration system universal by designing it to function in multiple modes: stationary calibration for initial setup and dynamic calibration during operation for ongoing accuracy. The same measuring device and control system handle both stationary and rotating calibration scenarios, eliminating the need for separate calibration procedures
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances calibration accuracy by correcting for aerodynamic influences, enabling frequent recalibration and reducing errors in load measurements, even in high wind conditions.
Implementation Method 1
measuring devices are used that record strains in small areas, e.g. strain gauges (SGs)
Implementation Method 2
fiber optic cables with fiber Bragg gratings
Implementation Method 3
The rotor blade load assumed to be known during the calibration process is usually the gravitational load, i.e., it is determined from the assumed known component mass and position in space
Data Source
Figure 1
Figure 2A~3
Figure 4A~5
AI summary
The invention relates to a method for calibrating a measuring device for measuring the load of a rotor blade of a wind turbine, wherein the wind turbine has a rotor with a rotor axis and a plurality of rotor blades adjustable in their blade angle, and for each rotor blade, at least one conversion factor is determined for calibration to convert a detected sensor value of a load sensor into a load value acting on the rotor blade, in particular in the region of its blade root, a sensor value is recorded by the load sensor in a detection step, and the conversion factor is calculated from a relationship between the sensor value detected in the detection step and the reference force acting on the rotor blade, wherein the reference force is calculated as a function of a weight force acting on the rotor blade, and the reference force is additionally determined as a function of a correction component,which takes into account a deviation between the reference force and the weight force.