In Situ Calibration of Wind Turbine Blade Load Sensors
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Solution Overview
Problem
Current methods for calibrating load sensors on wind turbines are costly and require dismounting blades, especially for offshore turbines, as they typically need to be recalibrated in a factory setting, which is impractical and expensive.
Innovation Solution
A method for in situ calibration of load sensors on wind turbines that involves determining the rotor azimuth angle and pitch angle, measuring loads, calculating theoretical loads, and comparing them to measured loads while the turbine is operational, allowing for automatic calibration without dismounting the blades and during normal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If load sensors are calibrated in a factory setting, then calibration reliability is improved, but calibration cost and complexity increase significantly
Solution Approach 1:
The wind turbine performs its own calibration using its operational data. The system uses measured loads from load sensors during normal operation, combines them with measured operational parameters (azimuth angle, pitch angle, wind speed), and automatically calculates calibration factors without external intervention. This self-calibration capability eliminates the need for complex factory calibration procedures while maintaining reliability.
Solution Approach 2:
The calibration process utilizes changes in operational parameters (azimuth angle, pitch angle, wind speed) during normal turbine operation to create diverse loading conditions. By collecting data across multiple operating states and parameter combinations, the system can reliably determine calibration factors without requiring controlled factory conditions, thus simplifying the calibration process while maintaining accuracy.
2Measurement precision
If blades are dismounted for calibration, then calibration precision is improved, but operational time and cost increase
Solution Approach 1:
The calibration process occurs continuously during normal turbine operation without interrupting power generation. The system collects load sensor data and operational parameters throughout the turbine's operation, processes this data to determine calibration factors, and applies these factors immediately. This continuous calibration approach eliminates downtime while maintaining precision through multiple measurements across various operating conditions.
Solution Approach 2:
The system continuously collects and stores load sensor measurements and operational parameters during normal operation, preparing the data set needed for calibration. By the time calibration is needed, the system already has accumulated sufficient data across multiple operating states, allowing immediate calibration without requiring blade disassembly or loss of operational time.
3Measurement precision
If special calibration procedures are used, then calibration accuracy is improved, but automation level decreases
Solution Approach 1:
The system uses feedback from multiple sources (load sensor measurements, azimuth angle sensors, pitch angle sensors, wind speed measurements) to continuously monitor turbine operation and automatically adjust calibration factors. The measured loads are compared with theoretical loads calculated from operational parameters, and calibration factors are automatically updated based on this feedback, achieving high accuracy through automated closed-loop control without manual intervention.
Solution Approach 2:
The patent replaces manual mechanical calibration procedures with automated computational methods. Instead of physically adjusting sensors during blade disassembly, the system uses computer algorithms to calculate calibration factors from operational data, substituting mechanical calibration actions with automated digital processing and calculation, thereby maintaining accuracy while maximizing automation.
Data Source
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AI summary
A method of in situ calibrating load sensors of a horizontal axis wind turbine is described. The wind turbine comprises a rotor including a hub and a number of wind turbine blades, which extend radially from the hub, the hub being connected to a drive train including a generator, which converts mechanical rotational motion of the rotor into electrical energy, wherein said number of blades comprises at least a first wind turbine blade provided with a number of first load sensors positioned in a first cross- section of the first wind turbine blade. The method comprises the steps of: a) determining a rotor azimuth angle of the first wind turbine blade, b) determining a pitch angle of the first wind turbine blade, c) measuring loads in the first cross-section of the first wind turbine blade using the first load sensors, d) calculating theoretical loads based on at least the rotor azimuth angle and the pitch angle of the blade determined in steps a) and b), e) comparing the loads measured in step c) with the theoretical loads calculated in step d), and f) calibrating the first load sensors based on the comparison of step e), wherein the calibration are based only on measurements carried out, when the generator is cut out.